M38A1 fuel tank cleaning?

Casey B · #1 03-11-11, 00:18

Hi Fellows..
Well I have to start from the begining again and do it correctly and see if the engine will run better. I cleaned and rebuilt the carb...the kit has two different springs for the accelerator pump and short one and a longer one...NOT the the spring for the metering rod. So I used the longer one like it had.

Put an inline fule filter in between the tank and pump. It caught a lot of large particles from the tank.
I took the sending unit out as well the pick up tube and it was fine except the element was loose so things got past it.
Then I see this stuff on the bottom of the tank. It appears to have gone in as liquid but then dried but can be rubbed off with your finger while still wet with fuel.

Any ideas what it is/ was for?

What do you recomend I clean the tank with when I do the final cleaning out and any tips on how to do it efficiently would be great?

Once cleaned I will rebuild and clean the carb, blow the lines with compressed air and new fuel filter.

I was told I should maybe consider an electric fuel pump as the old one has the rubber diaphram which may not be compatable with the alchol in todays fuels? YES/ Don't Bother?

Thanks to all again...!

rob love · #2 03-11-11, 00:35

Not sure what that crap is that's in your tank. I would suggest taking the tank to a radiator shop where they can properly clean it out, and seal the tank or repair any leaks.

I am still running on an original fuel pump just fine. There are kits out there with fresh alcohol compatible diaphragms and check valves, but mine will be an original. Zero issues.

The inline filter is important. Best to have one before the fuel pump, as the sediment can clog open the little check valves in the pump and cause it not to pump fuel. I install a second one at the carb just to make sure everything is good.

Phil Waterman · #3 03-11-11, 15:15

Hi Casey

Great pictures inside the tank, looks like the tank is in good condition other than what ever that gunk in the tank is. This doesn't look like normal varnish from evaporated gas, almost looks like something was dumped into the tank. Is all the gunk on the bottom of the tank?

Robs comment about taking it to a radiator shop is a good one, but be careful some shops use an etch solution which is OK on brass used in radiators but might take the coating off the steel.

So back to the gunk, it looks like the your fingers have made marks in it, can you get some out of the tank with out scratching the inside of the tank? If so try you might try the following to see if it will dissolve:

Really hot water ( I sort of suspect this may work)
Acetone
Straight alcohol
Automotive paint gun cleaner

Reason I suggest doing this on small samples is so you don't make the problem in the tank worse, for obvious reasons don't mix them together.

I would not use anything abrasive, as it looks like the steel in the tank is other wise in good condition.

One of the old methods of dealing with a problem like this was to use a gas tank sealant to seal the junk down, but as the new fuel mixes have dissolved two older type of tank sealants resulting in the same type of problem you already have I would not suggest using a sealant.

Please keep us posted on how you make out as your problem is one which any of us can end up dealing with.

Cheers Phil

cletrac (RIP) · #4 03-11-11, 15:58

I'd try taking it to the car wash first and see if that removes the gunk. If you get one with really hot water and lots of pressure it should work.

rob love · #5 03-11-11, 17:33

The tank appears to be one of the replacement tanks from the 80s. The give-away is the welded edges instead of the rolled edges of a factory gas tank. I'll check my spare one and see if the same gunk is on the bottom. It may be there to help seal the drain plug area as well as some of the welded seams. It is possible this was put in by the manufacturer and was never intended to see alcohol.

IIRC there is a baffle in these tanks which would make scraping half the tank impossible, but as suggested by the others, heat or solvents may remove the gunk.

Casey B · #6 03-11-11, 23:47

Is all the gunk on the bottom of the tank?

Yes it looks like it is only one the bottom of the tanks and from what I can see only on one side of the baffle and looks like it was poured in then the tank tilted to the same position as when I took the pictures.

Really hot water ( I sort of suspect this may work)
Acetone
Straight alcohol
Automotive paint gun cleaner

Please keep us posted on how you make out as your problem is one which any of us can end up dealing with

Well I am going to try just plain old gasoline first to see if it loosens then as you said Phil try the Hot watr from a kettle and a wood scraper then the others and see what this stuff is Feels and looks like fuel varnish. No holes in tank so we'll see have a radiator shop in mind to take it to but will try these first!

Rob where do you fit the upper fuel filter before the carb? just along the fuel line that runs to the input on the distributor side of the engine I am guessing?
A plastic fuel line filter is okay there...? heat? or would you go with a metal one? I used a plastic one on the fram rail pass side just near the spring shackle.
Thanks again and will let you know!

Casey B · #7 04-11-11, 01:36

Okay well here's the update.
Before puttinaanything in the tanks I tried to wipe with my hands and it just rubbed off in little flakes that were slightly shiny. So I am going to say a petrolium based productNow it was only in the one side of the tank nothing around the drain which is on the filler side.
I took a clothe an wiped the residue off which except for some globs which look like drippings from a fat fryer it all came off. I then poured HOt Boiling water in and agitated it and the stuff seemd to melt and wash away with help. A wood paint stir stick helped.
Then after pouring that out and wiping dry with a clean clothe I decided to try a little gasoline and it did nothing to the stuff except turn it to a greasy gooy substance that smeared rather then wiped away...So much for the petrolium based substance.
It is curiously where the pick up tube goes and is the same colour as the element the strains the fuel at the pick up tube.
What is that made of...? Spongy red pourus material in a cylinder? Could be that is not compatible with todays fuels. Or the goo could have been an additive poured in that did not mix with the feul aka STP? something like that Or even sugar as it does look like varnish or burnt caramel! The pattern of the goo seemed to radiate outwards from the pick up tube in a radial pattern as the paicks show and then drip down.

Well there you are mystery not solved but problem gone.

The tank Bottom has some small patches of surface rust so I will look at getting it coated for new fuels.
Do radiator repair places do sealing of fuel tanks? Or I can google I guess!

Thanks fellows!

rob love · #8 04-11-11, 02:01

Rad places do gas tanks. Or you can source some POR15 and do it yourself. I believe Lordco carries it in your province. It is not rocket science to apply.

SteveJ · #9 06-11-11, 23:47

since you are totally cleaning out the tank I would suggest installing an original in tank filter. This will save you cutting up your fuel lines. Midwest military has them and they can be cleaned periodically and reused as per the TM.

Casey B · #10 07-11-11, 02:50

It has one in there already a redish brown cylinder correct?

What are these made from and do you think I need a new one?

Too late on the fuel line cuts as I have already put an inline filter in before the fuel pump and glad i did the tanks filter element was loose so the gunk got to the filter. Thanks look forward to your reply!

Casey B · #11 07-11-11, 02:57

Hi Rob yes I found the POr15 coating now wanted to know how you would protect the drain hole just let it run through and then run a tap through the threads after or put a bolt through then try to cut away the residue or build up after it is dry?

Also I was told the running for a few minutes then dying could be the condensor you think maybe? New plugs proper gap and clean fuel rebuilt carb...Idled for a long time 15-20 mins and then when you put it under load it dies within a few minutes and is flooding and will not restart!

rob love · #12 07-11-11, 04:02

Condensors usually work or they don't. Coils on the other hand will do what you are describing.

Only problem with a fuel filter before the fuel pump is that all the crap that's sitting in the pump itself still will have to work it's way through the carb needle. If flooding was a problem before, it still will be for a short time yet.

To install a filter at the carb, remove the pipe to flare brass fitting and replace it with a male pipe to female pipe elbow. Install a 70s (actually should be an early 80s) Ford fuel filter into the elbow then install the original line onto the fuel filter. No need to cut lines.

I would just let the POR go through the drain plug and then clean up the threads with a tap. The POR is tough, but not as tough as steel so the tap will have no problem. Check the internet for tips on using the POR products...there are plenty out there including on their own site.

SteveJ · #13 07-11-11, 23:41

The reddish brown cylinder is a resin core filter which would
be the factory install. Its cleanable and normally would require periodic cleaning every six months under normal use. When I got my M38 in 97 the tank also was full of crud so I pulled it out cleaned and repaired it. I also cleaned the fuel filter,carb and flushed clean fuel through the pump which would be normal for the level of maintenance you are doing. My jeep ran excellent with no fuel glitches since. Last year I changed the fuel gauge sending unit as it was erratic. As I was in there I also replaced the fuel filter with a new one from midwest. Again its still running great.

If you have already cut the line and installed the inline its done. I would still replace or clean the one in the tank then if you ever decide to go back to factory spec its just a matter of replacing the fuel feed line as you know you have a good filter in the tank. The factory install is nice and clean no strange looking add ons. Less fittings less chance of a leak.

Casey B · #14 08-11-11, 23:59

Hi Rob well lot's of good advice but again nothing that can't be replaced should someone want it looking original..I have a pic of the fuel filter that I got for a ford Late 60's early 70's and it is common as you said with a 90 degree elbow and threads as well...the opposite end is not a female flared type. Is there one with this they could not find it in their data base...? There is a pic of what I got and would have to either make the hose go over the flared end of the fuel line or have to cut it to allow the hose to fit the end. I think it would fit over but if there is one that can be fitted without this hose Love to get a part number from you. Thanks Rob

rob love · #15 09-11-11, 00:53

My mistake: Ford started using these in 1981.

Try a Wix 33081, or a Fram G3596DP. Or right from Ford it is a FG795A. The end will match right up to the existing jeep fuel line. Be careful not to cross-thread it.

Here is a pic of one:

Casey B · #16 09-11-11, 06:21

Yes Got it tonight and it fits like a glove Rob! I'll coat the tank and let you know how it works out! thanks again!

Casey B · #17 15-11-11, 06:39

Have to ask if the liner in the filler neck can come out prior to coating the tank also if so does the ring at the neck opening that the cap screws onto also come off to allow the long funnel liner to come out as well?
I know i can seal the tank with this in but want to know if it comes out and easily?
thanks!

rob love · #18 15-11-11, 15:18

Need a photo to answer that one. If you are talking about the long metal tube with a screen on the bottom, then that is removable. But if you are talking about the metal tracks, then that does not come out. Nor does the neck piece that the cap locks onto.

Casey B · #19 15-11-11, 17:10

Yes Rob the long metal sleeve that the basket screen fits into at the bottom the does come out?
Pic is the first of the four on the first part of this post. It slides out then and fits past the filler neck opening where the cap attaches? It seems to be in pretty tight so I thought I'd ask before trying to loosen it up to get it out of the way for sealing.

rob love · #20 15-11-11, 18:31

Yes, that will come out. You have to turn it like you do the gas cap to remove it. They were normally with the early 50s jeep but not part of the Cdn2 and 3 series. Since your Jeep has one of the aftermarket tanks from the 80s, it was not really meant for that neck extension. Even the gas caps were not a very good fit on those tanks.

I believe their purpose was to extend the neck so you could pour your fuel in straight from the jerry can without the flex spout, as well as to hold the fuel strainer.

Casey B · #21 15-11-11, 19:04

Just to be sure this is the long tube that has such a tight fit it will not turn. It has the small loop on it to attach the chain for the cap and the rolled edge at the bottom tha holds the basket type of filter...I can't see any way for this to clear the lip that holds the cap as it is the size if the filler neck? I tried to budge it with a puller and all i am doing is rolling the edge at the bottom...Maybe some heat and some penitrating oil if it is really meant to come out? I have seen the piece you are talking about but this looks to be two pieces or halves welded together put in then capped off with the cap ring threads.

Casey B · #22 15-11-11, 19:14

here are some pics of the tube i am speaking of It is in very tight and i do not want to wreck it if it is not supposed to come out...You can see there is no real palce for this to go even if i did get it loose unles it folds or over laps to fit through the neck opening? I tried to gently pry where the indents are and nothing...tried a puller on the bottom and like I said am curling the lip over...Any thoughts other than heat and penitrating oil if this pieces does come out?

Casey B · #23 15-11-11, 19:57

after cleaning some rust off i found the spot weld no need to go on it does not come out...fixed the tube bottom ready to seal now thanks for all the help!