M35A stalling

[tmallow2004]

I have a M35A that is stalling after a few miles of travel. The fuel filters and air filter are all new and were changed a few months ago after an initial stall problem. The truck isn't driven all that much so really very few miles have been put on it since the filter changes.

What happenened last night is after maybe 5 miles, the truck stalled at 35 MPH in 4th gear and wouldnt restart until 5 minutes later. On return trip home from the restaurant, the truck stalled 3 more times, each time the stall occurring progressively sooner, and in 3rd, then 2nd gear. The last stall occured a mere 5 minutes of driving in 2nd gear at 10 mph - was driving slow for fear that a higher speed or gear was somehow doing this, based on the previous stalls. Finally had to have it towed home.

The vehicle will restart if allowed to sit for 5-10 minutes. But it will soon stall again therafter.

Basically, its like a fuel delivery problem related to temperature of the engine.

I'm wondering if there is water in the tank. Like many trucks of this age (1971), you can see rust depositions in the mesh screen inside the fuel tank and some in the fuel lines and in the 3 filters on the engine. Can not readily see layers of water and fuel in the tank though.

Could the injectors be clogging?

I also noticed that sometimes in the warm up phase, then engine sort of loops around in idle speed, at random. No set pattern. It comes and goes and isnt always occurring.

Lots of variables here. Need some sort of method to go about diagnosing the problem.

Thanks,

~Tim

 

[cranetruck]

Could be an air leak in the fuel system or even a pinched fuel line (check the line below the radiator in front....

 

[gringeltaube]

Is the in-tank fuel pump working?

G.

 

[Boatcarpenter]

Exact symptoms as I had a while ago and it turned out to be it was starving for fuel because a rusty sludge was clogging the primary filter in 40-60 miles. So, even though you changed the filters not too long ago, check the primary again and look for a rust colored sludge buildup in it. You may even find that the filter seems a little collapsed from the secondary pump trying to suck fuel through it. The solution was to drain the tank and clean it and then keep it as close to full as possible all the time so that the tank wouldn't form a slimey film of rust on it from all the condensation. Ran it a while after cleaning the tank and then changed all the filters again and it never skips a beat now.
Good luck,
BC

 

[maplehillfrm]

I would check your filters again like was stated, especially if you are seeing rust in the filters and such,, what part of the country are you in, is it cold?? th efuel could be gelling up or y ou may have ice in the filter, I am thinking it is probably a piece of rust either in the tank that is floating around and everyonce in a while it will be picked up by the pickup tube, or a piece of dirt that is doing the same thing either in the tank or the filter,, that is if it isnt gelled,, if you are in a cold area put some diesel treatment in it 911, powerservice, psst,, etc,,

doesnt matter how long ago you changed the filters if there is junk in the fuel it will clog that filter sometimes in a day or two, depending how much could be hours,,

 

[tmallow2004]

Thanks for the replies.

The in tank pump is working insofar as I can hear it when the rotating switch is rotated down prior to pressing the igniton button.

I'm in Florida. Last night it was only in the lower 50s. So, its not really too cold for gelling I reckon.

I think, based on other feedback here and what I've seen, its highly likely to be a rust sludge/particulate issue in the tank. To drain the tank and clean it seems like the best initial course of action for now. Was a hunch I had which appears to be confirmed here in a couple of the replies.

Another factor I failed to mention is that there is a pinhole leak near the top of the tank on its aft side end. That is without doubt a rust spot on the inside. There was a similar pinhol leak in the primary fuel filter housing under the engine. I replaced that housing with one that was clean. And if all this is the case, its probably safe to assume that the upper part of the tank has this rust issue, and hence rust depositions would show up in the filters as they did before.

What would be the best way to clean the tank? I'm assuming it will have to be removed for that.

Thanks in advance,

~Tim


What would be the best way to clean the tank?

 

[Lex_Ordo]

When I took delivery of my truck, I didn't have much fuel in the tank. I could see the bottom, and of course, I saw all the rust particles that accumilated over 37 years.

I used a magnet attached to a long rod to try and clean out as much of the debris I could. Then I filled up with a full tank of diesel, and changed the primary filter by replacing it with one of Jatonka's spin-on adapters.

I have not had any issues, but always keep a full tank, and plan on changing the primarys every couple of months to help facilitate a cleanout.

 

[Boatcarpenter]

I wasn't at home when I had to clean out the tank so I used what was at hand. I siphoned out most of the fuel except for the sludge and tidbits on the very bottom then pulled the plug and drained it. Believe it or not, I then used a garden hose with a straight nozzle on it and blasted the inside until it came clean. I could push the hose under ond over the baffles to get most everywhere. I then hung a small hair dryer in there on high for a couple of hours and it dried it very nicely. Filtered the fuel when I put it back in. Ran it a hundred miles or so and then changed all the filters again. Now when I bleed the primary before startup I am still getting nice clean fuel.
As to whether that is the best way to clean a tank, probably not; but it worked for me.
BC

 

[Big Mike's Motor Pool]

make sure the fording valve on the fuel cap isnt in the fording position. might not be venting causing vapor locking

 

[FreightTrain]

There is a fording valve on the tank cap?

 

[Big Mike's Motor Pool]

There is a fording valve on the tank cap?

yes, some trucks have it and some dont. my one m35 has a cap that says non vented and my other trucks cap says somthing like vented open normal operation and closed fording vapor lock. the little valve is on the bottom of the cap. you just twist it and go swimmin lol

 

[Big Mike's Motor Pool]

now that i think of it, this fording cap was probably part of a fording kit and not part of factory trucks. my truck at one time did have a fording kit which was pirated off and the hammer heads who got it prolly forgot the fuel cap

 

[turnerman]

I had an non turbo multifuel ldt465 that leaked oil into the combustion chamber and would hydrolock the motor when accelerating or under load but would idle fine. Let it sit for 10 minutes and would run and drive, then do it again. Never tore it apart but could have been valve seals or broke ring? Oh and it smoked white smoke too. If yours smokes... just a thought. Good luck!

 

[FreightTrain]

nah,My fording kit didn't have a tank cap.It was new in the box.Granted,it had to be removed from the box to be shipped but everything was there per the really crappy blueprints included.

 

[tmallow2004]

Turnerman,

The quesion of blow-by came up once. Was something I was concerned with. There is no white smoke, thank goodness. Just the black smoke under accleration loading. Something I understand as more or less normal.

So, I'm going to clean out the fuel tank over Christmas break when I have time. One thing I noticed is that the previous owner put an in-line glass fuel filter right on top of the tank on the feedline from it. Its just a generic cheap commercial unit. Not sure that was a good idea, except maybe to get a visual on the state of the accumulation. And yes.. you can see its pretty browninsh red with sludge. I'm going to yank off that sucker and toss it.

ATW,

~Tim

 

[cranetruck]

..........One thing I noticed is that the previous owner put an in-line glass fuel filter right on top of the tank on the feedline from it. Its just a generic cheap commercial unit. Not sure that was a good idea, except maybe to get a visual on the state of the accumulation. And yes.. you can see its pretty browninsh red with sludge. I'm going to yank off that sucker and toss it.

ATW,

~Tim

That filter is very likely not capable of handling the required fuel flow to the engine, get rid of it.

 

[tmallow2004]

Below is a photo of fuel samples I took yesterday. The vial at the left was fuel pulled out of the tank near the top in the fill port using a pipette. The middle graduated cylinder was fuel drained off from the input side of the cheap glass fuel filter the previous owner installed at the output feedline of the tank. The rust color is obviously due to the build up therein which led to the element collapsing under flow, and hence that clogging resulting in engine stall. The vial at the right is the fuel from the output side of that fuel filter. It is not as clean as the in-tank fuel as can be seen by its tinted darker color, but it is substancially cleaner than the input side.

This is the fuel filter that was summarily excised and charged with the crime of impersonating a deuce fuel filter...

The previous owner had also put in a Carter inline fuel pump about 15 inches up the line from the el-cheapo fuel filter. I haven't yet determined this but I bet the in-tank pump has failed due to being clogged. If so, I'm looking at replacing the in-tank pump. We will see as things progress.

And I agree with you, Cranetruck.. I doubt that filter was capable at delivering the flow rate needed even when clean.

~Tim

 

[gimpyrobb]

Yup drain that tank. I bet that little filter is WAY plugged.

 

[desertfox]

I may have noted this in another thread but bares repeating. On one of the deuces out of Santa Fe the engine started cutting out after about 3-400 mi after recovery. In fact on Memorial Day. Got it home. Pulled the primary and a trooper had failed to replace the spacer, washer and spring. Only putting in a new filter. Therefore the seconday looked like the color of your little filter and was swollen. I replace all 3 and have not had any problems since. I am ordering a spin-on primary from John Tennis. The problem with alot of deuces while sitting or months to years is if the fuel tanks are not full they will condensate and rust inside. Even in NM.

 

[dabtl]

A lot of the crap in the tank comes from years of having diesel fuel growing algae. Get an algae killer, from the auto supply house, and put in some. It helps get rid of the algae and the water problems as well.