• Welcome to this website/forum for people interested in the Morgan 38 Sailboat. Many of our members are 'owners' of Morgan 38s, but you don't need to be an owner to Register/Join.

Fuel Tank Cleaning / Fuel Polishing: Recent Experience

mpearson

Mark Pearson
Staff member
Wow. I recently finished cleaning our fuel tank and polishing the fuel. I am very glad I did this - there was an alarming amount of sediment and poop (really!) in the tank.


If you don't know if your tank has been cleaned recently, I’d highly recommend doing it. The following is probably “too much information” for a casual reader, but hopefully useful for someone considering doing this process.

Caveat #1: If you have a gasoline fuel tank (probably not a Morgan 38), don’t do this! There is a lot more danger of explosion & you could blow yourself and your boat up. You’ll want to be very aware of sparks and grounding.

Caveat #2: If you do this, be sure you know how to prime the fuel line to your engine. When you’re done, you will need to. It can be a little tricky. If you have a Perkins 4.108, I wrote a little cheat sheet many years ago here.

I used a new-age trick that I think is a game changer: an inexpensive ($40) endoscopic camera. This is a pencil-sized camera with bright lights that I could move around in the tank as I was inspecting and cleaning. I could watch things from my big & bright iPad (or computer) screen.


I don’t think the tank has ever been cleaned out. I know for certain that it hasn’t been in the last 15 years based on conversations with the most recent previous owner. But based on some of the things I found, I’d bet it has never been done in Zia’s 36 year life.

I had (7 years ago) removed the fuel gauge and peered down into the inspection hole (1-1/2”diameter) with an intense light. All I could see was black. I chose to close it back up and act like everything was OK. I rationalized it was probably a black steel tank and that’s why it was so dark in there. Spoiler Alert: it's a fiberglass tank with a shiny white gel coat surface. It was so coated with sediment, goop and crap that it looked like a cosmic black hole from which not even light could escape.


Our new Yanmar engine operates at very high pressures and I’d read a Nigel Caulder article about how filtration and clean fuel was even more important with these engines. Both my old Perkins manual and the new Yanmar manual recommend inspecting & cleaning the fuel tanks out annually. Yeah, right!

A note about particle sizes and filtration: A micron is one-millionth of a meter. The largest particle that a human can see with the naked eye is around 40 microns in size. Oddly, I cannot find any “official” micron rating on our Yanmar filter, but I’ve been told by one dealer that it is 2 micron, and by another that it is 10 micron.

I constructed a little polishing/cleaning rig from parts at Home Depot and Amazon.com. Total price was around $130. It polished the fuel in the tank to about 10 microns. In my opinion, that is very clean and ready for the Yanmar’s fuel filter.

1- Endoscopic Camera with Lights
2- 3/8” Copper Tube, Type L
3- WiFi Router, came with camera, allows iPad to view video
4- Pre-filter with Sight Glass
5- Diesel Fuel Pump, 12V, 30 GPH
6- R12T Fuel Filter w Water Separator
7- 2X4 Wood Stand
8- Fuel Hose, 3/8”
9- 5 Gallon Diesel Jerry Can

Perhaps more importantly: I cleaned the tank. We could easily polish the fuel to 10 microns but still have so much filth in our tank that wave action/bouncing could stir it all up, break it loose, etc. and plug our fuel filters. Precisely at a time when you don’t want a plugged filter & dead engine.

Some fuel polishing companies use high throughput pumps & filters to blast things loose (in theory). I’m quite sure that some of the gunk and poop I removed would not have been removed with just stronger pumping. And certainly I wouldn’t have been able to see it visually without the endoscopic camera.

I took the cheaper and slower approach and used a fuel pump that did 30 gallons/hour. I got a inexpensive Racor-like filter (hereinafter called R12T Fuel Filter) on Amazon.com with replaceable filters and a water trap. I hose clamped rags to the end of a copper pipe that was the intake, then I scrubbed and sucked it clean.

It took a two days of work and I went through a whole bag of those white rags from Home Depot. I plugged and replaced the R12T filter twice, so I went through 3 of those filters. I took apart and cleaned the pre-filter in the sink with water probably 20 times.

Here are the steps I took:
  1. I waited until the tank was less than 1/4 full. I only had 2 of the 5 gallon diesel jerry cans, and I reasoned that there should be about 10 gallons left. Note for the future: there was only about 6 gallons left when the gauge read 1/4 full.
  2. Removed the fuel gauge and started pumping through the filter and into the jerry cans. There was a huge amount of turbidity and very quickly the sight glass in the pre-filter was black and the bowl on the R12T Fuel Filter was black. This slowed flow down to a dribble.
  3. I decided I just wanted to get the fuel out of the tank and that I would use rags to mop out all the crap, rather than changing filters so frequently. So instead of moving the inlet around and stirring things up, I kept it quite stationary with the goal of only removing the fuel. It took about an hour to get the remaining 6 gallons out of the tank, and I stopped and cleaned the pre-filter about 10 times. In hindsight, my pre-filter was plugging even with the filter element taken out. Upon closer inspection, this was because the fuel needed to go through little holes that were about 1/16” diameter and many of the particles I was sucking out were bigger than that and plugging the holes. Also, I couldn’t find a rated throughput for this pre-filter, but I think 30 gallons/hr is unlikely.
  4. Then came the actual hard work. I cut the white rags into squares about 8 inches wide and hose clamped them to the end of the copper pipe. Using the endoscope, I scrubbed back and forth to clean the goop/sediment off the walls and bottom. See the "in action" video below. Repeated this a couple of dozen times. I added a gallon of my filtered diesel back when I needed more liquid to properly swab out the tank. When I started this step, the rags came out black with lots of sediment, metal shavings, slime, etc. They gradually got lighter and finally ended up being the pink color of the diesel. This took some time, but what the heck? It took 36 years for all this crap to build up so it seems reasonable that this step took 6 hours and a whole bag of rags to be clean again.
  5. I had to bend the copper tubing “up” a little bit when trying to push forward in the tank. The 3/8" copper tubing was Type L, which means it was fairly soft and could be bent to reach around corners or over humps. This would not have worked if it was rigid copper or a piece of dowel. There is a sump below the access port and where the fuel intake is located. See photo of the sump below. A straight probe would not be able to get over the edge of the sump, and into the forward portion of the tank. I was able to get about 36” forward of the access hole. That is also roughly the distance to the back of the mast, so I think I got the entire tank.
  6. During the swabbing of the tank I made a startling discovery: a brown/black object seemed to dart by the camera several times then disappear. Oh my god, is there something alive down there? Nope. It turns out there were some clumps of epoxy that literally looked like pieces of dog poop. They had only slightly negative buoyancy so if they were touched they would skitter across the tank like an air hockey puck. I luckily had an 18” long extraction tool and was able to reach in and pull them out. There were three different chunks and after I got them out I recognized it as a very hard/tough epoxy or polyester resin that I had seen used for tabbing when we stripped out the old icebox. I have no idea why they would be in the fuel tank but I’d say there is a 99% chance they were in there when Zia was built.
  7. I taped a brush to the end of the copper pipe and brushed the floor and walls to remove the attached grime. It was a soft bristle brush so I wouldn’t scratch the gel coat.
  8. Added the 5 gallons of filtered diesel to the tank and pumped it into the can again. This time it went very quickly and the little pump was able to move the fuel at its rated capacity of 30 gallons/hr.

Here are my notes with 20/20 hindsight:
  1. There is no way I would have left for our previous voyage in the Pacific up to British Columbia knowing there was that much junk in the fuel tank. To me, it’s really surprising we didn’t plug our fuel filters at a bad time. From now on, I’m going to inspect and clean the tank every year. It won’t be a time consuming thing going forward.
  2. I started out with the copper intake pipe being too long (6 ft) and it got in the way. Trimmed it down to 40" which was much more maneuverable.
  3. At one point I tried using those fuel absorbent pads instead of cloth rags. No bueno. They broke apart quite quickly and cloth rags worked better.
  4. I taped my camera to the tubing with duct tape, but the diesel dissolved the adhesive over time. Need to come up with a better way of attaching the camera to the tubing. Maybe thick rubber bands?
  5. The endoscopic camera was for sure the way to do this. It takes a little practice to get used to. Bend the copper tubing a little bit where the fuel hose attaches. This gives you a reference point for rotating and swinging the tubing. Swing the camera left and right and up and down. Rotate the camera until it is oriented to match your motion before taping it down. Otherwise you have the strange sensation of moving it left but it appears to move right, etc.
  6. It was very good that I had a flexible grabber tool (see below) available to get the petrified dog crap out of the tank. I don’t think there would be any other way to remove it. Certainly a high pressure hose wouldn’t have washed it out, it barely fit through the 1-1/2” access hole.
  7. I was a little surprised that there wasn’t more water in the tank. In fact, I didn’t have any noticeable buildup of water in the R12T fuel filter.
  8. Next time I want to figure out a way to pivot the camera up so I can look at the top of the tank. Rick Dowe (on this forum) reports he used a mirror and was able to see that baffles were hanging down from the top. I think that's true but I didn't see them. I’d like to get some good photos of those for reference.

Videos

 
Last edited:

scupper

Vern Gliot
Found the same "poop" in my tank. I was surprised to find that kind of debris that was obviously there from time of construction.
 

rickdowe2

Richard Dowe
When I had the fuel tank cover plate off for cleaning I put my phone inside and snapped several pictures. Of course I did not back pictures up at that time and they were lost. If I recall the top of the tank appeared to be glued to the underside of the integrated fiberglass structure with a black substance. I too found small bits of black crap in the tank. Luckily my tank was relatively clean.
 

terry_thatcher

Terence Thatcher
Mark, you did this without taking off the steel plate on the top of the tank? What a job. I had my fuel tank and fuel professionally polished a few years back. Mine was so clean the guy gave up after an hour. No dirt was showing up in his multiple filters. (He advertises in 48 North.) But his process would not have removed petrified dog poop.
 

mpearson

Mark Pearson
Staff member
Hi Terry - yes, this was without taking the steel plate off. The plate didn't look like it was very big and I didn't want to drill holes in the cabin sole. That's interesting yours was so clean and mine was so filthy. Maybe the previous owner had cleaned yours? But you've owned Adavida for a long time. Hmmm.
 

schlepper

John m. Harrison
This is a very timely piece Mark, thank you! I was readying for a Regatta in Sarasota Bay in late April and was motor sailing under a bridge... we got about 1/8-1/4 mile past the bridge and caught a puff of wind and healed.... when we healed, it wasn't long before the engine conked out. We went ahead with the Regatta of course, and then sailed all the way back to the entrance to the Yacht Club when we ran out of wind... got towed in... I thought I was out of fuel and that my gauge, which was registering 1/4 tank was in fact empty when I did the average burn rates on previous fill ups vs. hour meter.

When we got towed the 150-200 hards to the fuel dock, we filled it up and it held 28 gallons. So there was approximately 12 gallons still in there. I turned off my auto-bilge switch just in case, as I had some diesel spill into the bilge when I filled up last year. But figured it was the fill hose and I would 'get to it at some point'... Now I am not sure if it's the fill hose or the steel plate, or the fuel hose or return line... or all of it?

I was curious if anyone has the dimensions of the fuel tank. I know it's supposed to be 40 gallons, but have no idea of it's inside dimensions. Trying to figure if the degree of heel was enough for the pickup tube to have sucked in air.

In any case, does anyone have a pictorial on how to remove that plate, what to replace the black rubber gasket with (or is it even rubber, and where do you get that type of diesel resistant product?), how to cut the deck so you can access all of it? Along with the holding tank in the keel and the galley counter coming across the centerline of the companionway, this fuel tank thing is a design fail in my opinion. That is too important an item to have it where you cannot easily service it.
 
Last edited by a moderator:

mpearson

Mark Pearson
Staff member
Hi John - so did your engine start up after getting fuel? Without changing the fuel filter or bleeding?

From my measurements/observations, the tank seems to actually hold approximately 40 gallons. There is a little sump area where the intake is located so I would say you'd need to be down to a few gallons before normal heeling could affect the intake. It seems you still had 10-12 gallons so I wouldn't think that would be the issue.

After we installed our new engine, the first time we did significant heeling the engine quit shortly thereafter. I primed/bled the fuel line and it worked again and has always worked since. My theory was there were air bubbles someplace in the fuel line that moved around because of the heeling.

Dimensions? It's an odd shaped thing because of the way it's fit into the boat so full dimensions would be kind of complicated, I think. In general, I believe it's about 38" from front to back, and I remember it was 11" deep where the access port is. I don't recall seeing a drawing of the fuel tank and if anyone has one, please post it.

Design Fail? I don't know if I'd go that far. I'd probably call it "sub optimal". Like most boats built back then (and some built today) there wasn't always a lot of thought/design put into all aspects of access & maintenance. It's like I tell new crew during the safety briefing: Zia is one big "tripping hazard" because she was built before the term "tripping hazard" was coined/invented.

This winter I might try to figure out how to retro-fit a better way to easily remove the plate for access to the tank. I did all of the cleaning described above by going through the 1-1/2" hole where the fuel gauge is placed.

Gasket Material? I went to an automotive store and explained what I needed and they sold me a little roll of gasket material for about $10.

Cheers,
-Mark
 
Last edited:
Easiest way to bleed is to install an inline Facet electric fuel pump mounted in the drawer space under the settee. Mount as close to the tank as possible to eliminate vacuum leaks.
 

dave_a

Dave Ahlers
Yes, John! And its a great backup for the engine's mechanical fuel pump. Belts & suspenders.

I pulled out an incredible amount of debris (sheets of tar, bugs, who knows what) from my tank. I clogged up a giant Racor 700 filter cleaning the Morgan tank. I did this after watching the Coast Guard tow a Nonsuch into Oswego, NY after a failed very bumpy powered crossing of Lake Ontario. The constant pounding into a south wind stirred up all the bugs and tar. Fouled his filter completely. (It ruins your injectors as well long term). Swore that wouldn't be me!
This is a maintenance issue. Deferred maintenance has its pitfalls....and you defer at your own risk.
Every old diesel fuel tank has sludge & debris (IMHO).
 

dave_a

Dave Ahlers
Marc, my advice would be to look for a fuel polishing / cleaning service and see what the cost would be. Make sure you tell them its a 40 gallon tank and the opening hole size of the sender (unless you're able to take the top flange cap. Some guys are set up for big tanks and some for small. A pro can knock it out in a hour or two. I spent hours probing with a copper pipe, scraping the sides and had a diesel high volume fuel pump. I do not think siphoning will accomplish much.
Once done I never had to change a racor 500 filter again, but I used biocide and fuel conditioner with every fill up
 

rickdowe2

Richard Dowe
John, when I cleaned out my fuel tank I removed the small settee forward of the sink. It is only held in by 6 to 8 I screws. Two at the top of the opening to the hidden compartment, after you remove the drawer there are two on the forward frame, two on the port frame and two on the aft frame after that the unit can be removed. From that point I needed to drill two holes in the floor to access two screws, later you can insert tapered bungs. After removing the hoses and the rest of the screws the plate should slide off. I used a cork/rubber gasket and some Permatex to seal the plate.
Rick
 

schlepper

John m. Harrison
I haven't been on the site in a couple of weeks... sorry to not have responded.

I pulled the tank gauge out and sent a LED probe into the tank. Much of the tank was clean and white, looks gelcoated. Where the tank level was down, I could move the probe to view below fuel level and above it and it gave good perspective. That is the good part. The bad part is that there are sections in the tank that are black and likely algae or just grime that will be drawn to diesel fuel over time. I plan to take the tank top off and clean it all up, but since I just filled up, I won't be doing it until the fuel level is down much further which may be awhile. With that said, my fuel filter under the galley sink is clear as a can be and nothing in the bottom of the site bowl of the Racor.

I think Jim Cleary or Terry Hatcher asked if I had to bleed etc. after my engine conked out. I filled up the tank, did a bleed of the IP (air bubbles came gurgling out) and then cracked the #1 injector til fuel came out with a spin of the starter, re-tightened and cranked it for a bit with the raw water valve shut and finally, she spit and sputtered back to life. I haven't had any trouble since after about 10 hours of motoring/motor sailing around Gulfport and Tampa Bay last week. The air in the line, not sure how I got it, but am going to get that top plate off and inspect the pickup tube. I want to be sure there is no crack in it within the tank that then sucks air in the line over time until it causes a shutdown. I've had air getting into the fuel lines several times over the past 18 months after almost 6 years of flawlessly running with regular oil, filter and fuel filter changes. I've gotta figure out the source of that air as I know one day it's going to quit in exactly the worst possible place and/or conditions.

The tank access should have been done with a plate to pull up from the floor and then have full access to all of it. The way it's constructed, it's like the tank plate was an afterthought... or the designer built it and then decided to put a settee on top of part of it. Nuts in my opinion.
 

schlepper

John m. Harrison
Okay, so I had the fuel polished and the polish guy said my tank was like a 7 on a scale of 1 to 10 with 1 being the worst. With that said, here is what the pictures look like of the filter on his stanless steel progressive canister filter. I lost about 7-10 gallons of fuel that was just extremely dirty. If my tank was a 7, I would hate to think what a 1 would look like.
 

Lukas Svrcek

New Member
Hi everyone, I'm about to clean my fuel tank. Following what people done in this post is what im going to do.
1. remove settee
2. make bung holes
3. take off access plate
4. pump out/polish and not sure if I'm able to stick my hand down and touch the bottom of the tank - if so I will try to wipe it with towels (any recommendations if I can use some solvent ?)
5. what do you guys recommend to reseal the access plate ?

Thanks in advance.

I attached a pic of my access plate.
 

Attachments

Last edited:

mpearson

Mark Pearson
Staff member
Hi Lukas! Be sure to take a bunch of photos and post some notes for us, please. I plan to do the same thing and get in thru the access plate instead of the 1-1/2” hole like I did when I started this thread. Even with the access plate off, I would think that rags strapped onto a piece of flexible copper tubing would help you reach everything.

In re-reading this thread, I’m still surprised how absolutely filthy our tank was ... and that others seem to have quite clean tanks.

For re-sealing the access plate I would think you could use diesel-rated gasket material from an auto supply store.
 
Last edited:

Coy McDonald

New Member
I am faced with the same issue as we speak. I have had black fuel ever since I bought Delia four years ago. I am currently in the boatyard and I was going to ask the guys to clean the tank but after reading this thread I don't think I want to pay boatyard labor rates for what Mark described as, "two days of work." I am very curious to hear how Lukas does with his approach. For me removing the settee may require removal of my AC unit as well.
 

jimcleary

James M. Cleary
To use an electric fuel pump to pump past the engine mounted lift pump should not be a problem. On my Yanmar the engine is rotated by hand until the cam shaft riven arm that drives the diaphragm pump is at the top of it's travel at the pump. That keeps the diaphragm up out of the way. The electric pump is then clear to pump up both filters and to bleed any air out.

Jim
 

Lukas Svrcek

New Member
My recent attempt to remove my access plate.

It didn't go as planned. I found out that my settee is glassed in very well. If I was going to take out the battery pan it was going to be a pretty big demo project. I didn't want to demolish the original woodwork.
IMG_20200524_065828.jpg

Plan B was to remove the fuel gauge, which would require cutting some of the floor.
IMG_20200524_110616.jpg

Plan C was to use the fill up elbow. Which I did
IMG_20200524_074830.jpg

I looked inside with endoscopic camera, it was pretty black but not as bad as I thought.
1590331042380.jpg
I did the polishing, I think I did 4 filtrations using similar system you created @mpearson
IMG_20200524_094505.jpgIMG_20200524_094508.jpg
So the fuel did get cleaner but not clean enough.

My next round is going to include a rotary brush that can mix and move some of the dirt. Trying to figure out what I can fit through the fill elbow.

I heard some one telling me if I put some diesel cleaner and let it sit there for few weeks it should take care of it if I pump it out.

The last observation was that my diesel was yellow not red, not sure what that means.
 

schlepper

John m. Harrison
I think having your fuel polished by a professional is well worth it. I had mine done late last Summer and I was shocked at the fine particulate his filters picked up and then the heavier stuff that settled in the bottom of his stainless filter drum. We put in chemical biocide treatment for the algae and I plan to use it at every fill up. It is far cheaper to strive to have clean fuel than it is to have to pull injectors (if you can get them out) and have to replace or have them rebuilt from dirty fuel..... clean fuel, clean oil and proper coolant is a key to longevity and good service life with a diesel (well, and no air in the lines but that goes without saying!)....
 

dave_a

Dave Ahlers
What John said. A pro's equipment is impressive in comparison to what we owners can create. Pumps and filters can take up an entire trailer.
As a guy who DIY'd his own tank, if you want to quickly and thoroughly clean the tank a pro service might be the answer.
 

mpearson

Mark Pearson
Staff member
Dave & John - I hear what you're saying and I'm sure it's true in your cases.

Our tank was so filthy, though, I don't think just fuel polishing (even with big pumps and filters) would have removed the grime that was caked on the walls & floor of our tank. I had to scrub it quite hard and repeatedly with a rag to get the gunk off. Also the bigger chunks would not have fit through their pipes, I think. I barely got it out of our 1-1/2" hole.

I'm sure there is a wide spectrum of people who do "professional" fuel polishing. Maybe some of them have scrubbers that let them scrub the walls/floor. The few I talked with didn't have that kind of gear, though, and they strictly polished the fuel.

I agree - in hindsight if someone could do it well and actually scrub the walls as they polished, I'd much rather pay them some $ and save myself the time.
 
The fuel polisher I hired to pump out my tank prior to cleaning had some basic plastic rods that he used to agitate the fuel and scrape the bottom of the tank a bit while he pumped, but as with Mark and some others on the thread the state of my tank was such that this was really only scratching the surface of what was needed.

At least in Maryland the company I hired is one of the only options, and they were not equipped to actually clean the tank, just run the fuel through their filters. I didn't bother with that, just had him haul away the dirty fuel and started over with new diesel (and a healthy dose of biocide) after scrubbing the tank as best I could via a method basically the same as Mark's, though with the entire access panel removed so I had a little more room to maneuver.
 

schlepper

John m. Harrison
I've had my fuel professionally polished. They do not scrub the inside of your tank. If you want the inside squeaky clean, you'll likely need to remove the steel plate that is the tank cover with fill hoses, vent lines and fuel supply lines, put a stick and rage down in there with some solvent and cleaner and swirl it around. I have not done that. To have my fuel polished, I simply removed the fuel gauge unit and it was plenty of room for the polisher to take fuel out to polish it and then once he was almost finished with it, to pump it back in. As previously referenced, that effort took a good deal of fine silt/algae/etc. out of the fuel and as well, he picked up some grit from the bottom as he suctioned the fuel out. I'll attach pictures of his rig, the cloth filter and what it screened out, the bottom of his stainless filtration unit.... and see what ya'll think.
1590544813246.jpeg1590545129240.jpeg1590544943329.jpeg1590544985120.jpeg1590545018779.jpeg1590544943329.jpeg1590544985120.jpeg1590545018779.jpeg1590544985120.jpeg
 

terry_thatcher

Terence Thatcher
My fuel gauge has never been reliable and I finally installed a Hart Tank Tender, which I love. But I still have the old gauge sitting on top of the tank. It must have some big arm in the tank. I am not sure I could remove the gauge screws, but if I did, would the internal mechanism come out or would the whole tank top plate need to be removed? And, by the way, when I had my fuel polished, the operator had a tough time figuring out how to get into the tank with his two hoses. One pumped the fuel out and the other was a kind of wand that shot the removed fuel back in under pressure. I know one went in the fuel fill pipe attached to the tank, but I don't remember where the other one went. Not down thru the gauge hole, I know that. I was lucky. Fuel was quite clean. I was fixing a problem that I thought was caused by dirty fuel and turned out to be a collapsed air vent hose that caused periodic failure of fuel transfer from tank to lift pump.
 

jimcleary

James M. Cleary
Terry
I have removed the fuel gauge a number of times for cleaning purposes and it is very easy to get out. The only issue is accessing the One screw that is hidden under the cabin sole. To do that I drilled a 1/4" hole in the sole over the screw. The mechanical float mechanism below the gauge angles out of the opening without a problem.

Jim
 
I too removed the fuel gauge and it was indeed pretty straightforward. I was told by the professional fuel polisher to be sure to mark it before you remove, as it needs to be in the correct orientation for the float arm to work properly. Perhaps yours was reinstalled incorrectly at some point and that is the source of unreliability?
 

dave_a

Dave Ahlers
I replaced mine with a standard marine gauge from Tempo (if I recall correctly). You just need to know the depth of tank to buy the right gauge.
But as the Morgan tank is is not uniform in shape you might want to recalibrate the gauge face in what ever increments are meaningful to you.
A Sharpie pen in 5 gal. increments worked for me.
 
Top