5 ton misses and dies

[bradmachine]

my M818 barely starts, misses and then dies at idle.... the last couple of times I drove it , it would die at a stop sign,,,, when left to idle, but would start ok and run if you gave it some throttle.... but now I think it is missing..... it has fuel... I'm thinking an injector is fouled.??. anybody got experience with this kind of problem.?..

 

[Carlo]

I have a M931 with the same problem plus a few things more! Hard to start (only on either), Surges RPM up and down. Tanks are clean, filter is clean, lines are free. Do you know of a in pump filter?

 

[USMC4302]

When was the last time you changed the fuel filter(s)? Check the easy stuff first

 

[Carlo]

I changed the filter on sunday and it made no difference. I even went so far as to remove the filter and it made zero difference....

 

[M813A1]

Sounds like you might have an air leak in a fuel line . try and back pressure the tank and use some soapy water at all of the joint in the fuel line and see if you have any bubbles. only use about 5 psi so you do not blow up a line or the tank . also check the cross over lines and selector switch for leaks because many guys have posted that the selector lever is their problems

 

[hemichallenger]

I have a M931 with the same problem plus a few things more! Hard to start (only on either), Surges RPM up and down. Tanks are clean, filter is clean, lines are free. Do you know of a in pump filter?

Sounds like this one is sucking air from some were. I have had a few that the small line at the hand pump has been cracked. I usally take air from a large compressor and a couple rags and force it into the fuel tank with the truck off. You should find a wet spot or drip. If you do not have a good air supply you just need to inspect the suction lines and fittings. They will not leak because they are on suction.

 

[augiedoggy]

Yep, what the others said. I had a air leak in the lines at the tanks selector and
verified this was the problem by disconnecting the fuel inlet line at the injector pump (under hood)
and running a large hose from a fuel can directly into fuel pump. the pump is drawing fuel
From the can only and mine ran beautiful like this. I knew where to go from there!

 

[Carlo]

Well last night I checked the mini filter on the top of the pump and it was "new". So as you say its time to work my way back. I will make a setup so I can try 2 liters of fuel from a jug direct to the pump and then presurize the hose leading from the pump back to the valves / tanks and squirt some soapy water stuff to look for bubbles. Its a pain in the but, BUT I prefer to find a hose problem instead of a pump problem. In Italy the pump shops charge €250.00 just to test the pump!
THANKS and will keep you posted.

 

[Floridianson]

Most of the trucks we get need all rubber fuel lines replaced. remove tool box and step and hope you have all barbed fittings. Cut them loose get new rubber use Q tip put some lube on the in side of the hose and push like heck till they bottom out. Start there

 

[Carlo]

You are up late or early!

Thanks for the tip. I just checked them last week but ater all the feed back I got from the site 94% are saying the hoses and you also confirmed it.. Im planing on bringing the truck down to my shop today or max tomorrow and check these hoses.

Thanks to you and everyone for the help!

 

[WillWagner]

The screen filter in the pump is only there to stop debris from going into the injectors if there were to be a pump failure. The flow is backward, it filters from the inside out and there is a magnet in there to pick up broken pump parts. Looking at it will do no good. If the engine runs, the filter will be fine.

Bradmachine, is there any smoke? If so, what color?

 

[WillWagner]

The screen filter in the pump is only there to stop debris from going into the injectors if there were to be a pump failure. The flow is backward, it filters from the inside out and there is a magnet in there to pick up broken pump parts. Looking at it will do no good. If the engine runs, the filter will be fine.

Bradmachine, is there any smoke? If so, what color?

 

[FormerNewMVGuy]

I had alot of problems that are simalar to yours, I started at the pump and worked my way back, new lines , new filter, and still had problems, what i found was , The pickup tube in the tank is made of steel, it had pin holes in about an inch from the top, So it was sucking air all the time.

Also make sure that the square washer on the bolt for the filter can is set properlly in the square hole, if you have to take it off the bolt and pound it flat.

 

[Carlo]

Hey there and thanks for the info.

Im checking the lines tonight again. Plus first Im putting a 2 liter can of dsl direct to the pump so I can see if it runs right. I want to remove the pump from the list and then move back. MANY members have said the tube from injection pump to the filter and then filter to selector valve (left and right tanks) are sure to be rotten.
I cant wait to get home!
Thanks

 

[EMD567]

Also, the suction tube in the tank is steel, and can develop pin holes from rust. I replaced mine with copper, as the steel tube was very very thin.

 

[Carlo]

Thanks John. Im working my way from the pump to the tank tonight by next morning Im going to find the leak or else!!

 

[Dukeman]

Copper line in diesel fuel? Is that ok? I would have used stainless steel, or brake line.

 

[WillWagner]

Copper line in diesel fuel? Is that ok? I would have used stainless steel, or brake line.

Copper and diesel don't hurt each other. In the old days, that's what was used.

 

[FormerNewMVGuy]

I made mine form copper also, been over a year without any problems, Plus it was what i had in the shop that thst worked.