Fuel system issue

[Mos68x]

Last night I went out for a ride and quickly found myself stuck and stumped. I hit a bump that didn't look rough, but bounced us around like popcorn in the cab. A short distance after that the truck died with no notice. Fuel tank was still full (3/4-7/, so I figured to see if if there was air in the line. After burping a bit of air I got the truck started again and kept on driving...or so I thought. This happened three times in a mile before figured I would let it run at idle for a bit. Still died even sitting still with idle at 1500. Dies in a couple minutes. Couldn't find any leaks in the fuel line, but the truck had water and dirt all over it since we had gone through some puddles and mud. Figured I would wait till today to look for leaks in the fuel lines after everything had dried. Since my truck started out as a van body, my fuel tank had the extra fuel pickup port. I took it off before I left and I'm going to see if I have some fittings to put an air pressure regulator on it and pressurize the tank and fuel system so I can figure out where it is picking air in the fuel system. Right now (if the lines end up being leak-free) my suspicion is the pump and primer assembly, but please speak up if you have had any experience with this. I was planning on fixing one of my tires today instead, but this takes precedence since the truck is a couple miles away on a dirt road unsecured.

 

[simp5782]

Search........

https://r.tapatalk.com/shareLink?ur...share_tid=142769&share_fid=20191&share_type=t


Start with the basics. Filters clogged. Fuel to lift pump. Fuel to injection pump. Troubleshoot. Not too much help you can ask for when you haven't narrowed down the 300 things it could be for people 2000miles away

On another note. The condition this truck was in when you bought it. Would be best to replace all your lines and crap anyways.

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[74M35A2]

Your fuel tank pickup tube to elbow junction probably cracked from the bump. Common in these trucks. I'm working with a guy right now to make stainless steel replacements which are TIG welded instead of soldered copper.

Bring an outboard fuel tank with primer bulb, plumb that into the lift pump inlet, and use that to get the truck home. Route the return line to it also if you can, or be prepared to keep refilling it during your trip, and make sure your truck tank does not overflow. Redo fuel suction side of the system once you are home.
http://www.steelsoldiers.com/showthread.php?167854-Stainless-Steel-M939-Fuel-Tank-Dip-Tubes-and-Hoses&highlight=


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[Csm Davis]

Pickup is probably okay, he can prime it. Would help to know what truck you have ?
No need to hook up regulator and such just a simple few puffs from a hand held air blower valve no more than 3-5 psi, more can rupture the tank.

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[Mos68x]

I was just putting it up there on what I came across, mind you everything that was done was at night so it wasn't easy to see anything. I suspect the primer lift pump but I want to make sure that it isn't a break in the fuel line somewhere first. I can do that with the air pressure as well as get it back home, but I need to plug the vents and use a regulator for that to work. There is a bit of damage to the fuel lines because of some jackass that tried to forklift the truck, Csm Davis saw most of it but I found more since I left his place. 74M35A2, are you talking about at the tank? I tried puffing the system last night but all I got was air bubbles in the tank and besides that most of the truck was still wet so I wouldn't have been able to see anything. Reason I suspect fuel lift pump is because no matter how long I sit on the fender and hand pump it, it will still burp a good bit of air. I tried looking for rebuild kits for it instead of replacing it, but I didn't have any luck. I'm sure there are o-rings or seals that can fix the problem inside of it without having to replace it every time one goes bad. Cheapest I've found so far has been $50 on ericks, but that doesn't look like it includes the mounting gasket.

 

[Csm Davis]

Okay bud I honestly forgot who I was answering so it is on a M934A2 8.3l . You can find a cheaper pump keep looking but I would look real close at all the fittings on and around where the idiots forklifted it.

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[Mos68x]

Well I got it back home, only took a few times of losing its prime once I put some air to the tank. Found the leak though, the fitting at tank. Going to look into a better solution.

 

[M35A2-AZ]

View attachment 680048

74M35A2, Nice upgrade!! I had a truck that the pickup tube was broken and would lose the prime and not idle that well.

 

[Csm Davis]

Glad you got it back up and running

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[Csm Davis]

74M35A2, Nice upgrade!! I had a truck that the pickup tube was broken and would lose the prime and not idle that well.

You need to quit posting and driving especially in the rain.

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[Mos68x]

View attachment 680048

Beautiful! I want some for mine.

 

[Mos68x]

To get it home I had to put pressure to the tank, once I found the right amount lol it was a fiddly dance of too much and too little. But I got the truck and a few other things home after losing a few gals of diesel. I might try to fix it today, but if I can't it's not a big deal, since I have other things to deal with too.

 

[Mos68x]

I got the old fitting for the fuel line itself loose, cleaned it up and rethreaded it into the pickup tube fitting and tightened. Still leaked, but far less, and this time only at the base of pickup tube. Tried to take it off, but wasn't thinking at first and wrenched in the middle where it is the weakest and buggered the threads enough to keep me from rethreading the fuel line back into the pickup tube fitting.

 

[Ford Mechanic]

I tried to rebuild my lift pump, it still leaked. There is some square O rings that I couldn't find. I bought a new one from Cummins and chunked the old one.

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[simp5782]

24v 35gph electric is Napa # E8131.

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[Mos68x]

24v 35gph electric is Napa # E8131.Sent from my SM-G935P using Tapatalk

I'm really tempted once I fix this fitting issue.

 

[Mos68x]

Hope we those pics better explain what I was trying to describe.

 

[Mos68x]

**** fitting stripped out when I finally got everything together. Going to have to find a fix for this, but it'll probably be down till next month anyways. I might just wait anyways so that I can I get the J844 type B fittings and hose for it instead.

 

[Mos68x]

Got something figured out. By 'figured out', I mean redneck style lol I do still have to verify that what I did will work but I'm fairly confident it'll work. My neighbor had a 1/2" MNPT compression fitting for 1/2" tubing so we put it in the drill chuck and ground enough of the threads off until I could it in the stock fitting. Used the vise to 'press fit' it in place, then we soldered it. Had to resolder the drop tube too since all that heat got it loose. Holds some pressure and vacuum so I'm happy. Once payday rolls around I'll replace the entire line with J844 NT100 so I don't have to worry about any more cracks in the fuel line, or at least not for a while anyways. I'll post pictures tomorrow, I didn't have any light after I waked home.

 

[Mos68x]

Works for now, no leaks. Couple weeks I'll order some J844 and fittings to replace that whole line