1994 M998A1 Stalling and dying after a mile or two

[Gunthar81]

I have searched the forums but haven't seen anything like what I am experiencing. I have had this issue for a year and just can't seem to nail it down.

The issue is that it starts perfectly, idles perfectly, drives perfectly, accelerates and slows with zero issues, and does not overheat at all steady at around 220. The issue is when you drive it, it reaches operating temp, and you make it about a mile or two, maybe 20 minutes, it starts losing power and eventually stalls out and dies. Sometimes you can immediately restart but it does the same thing when you accelerate. If you wait a few minutes it will start right up drive about 100 yards then start the cycle all over again. I have replaced the fuel pump which was not putting out enough pressure, still the same issue. I changed out the thermostat because it was overheating before, still the same issue. I have replaced the entire fuel load with brand new fuel and changed the fuel filter twice, the same issue. I am at a loss please help...

 

[REF]

Have you tried driving it with the fuel cap removed ? The air vent may be plugged up causing a vacuum in the fuel system.

 

[Action]

Unplug the wire on top of injection pump, so it wont start. Take doghouse off. Remove the input hose from top of filter can. Put paper towels under open hose. Crank engine. Do you see good flow there? That comes straight from the lift pump.

 

[Milcommoguy]

How about a little back story.... The what, where, when, model.... picture ? Just asking.

In my driveway I would put a simple-cheap vacuum / pressure gauge into the end of the water separator hose hanging on the outside left footwell. Easiest to get to... no fuss & quick. Make a good seal. Open the little drain valve and crank it over or have it running? 3 PSI plus should be OK.... BUT more is better.

??? Finding any junk it the filter / housing. Seals good and mating tight. If all is good no leaks... should hold pressure for a bit of time. Mine runs at 8 PSI and will hold for 10 minutes AFTER engine is shut down before slowing bleeding down.

Same hose...Flow is important too and see if it fill a beer bottle up quickly. 15 seconds and running over. Pour back into tank before Billy Bob takes a sip.

Do you have check valves in line. Something to else CHECK. LOL

Good catch on the cap off run test TOO

More and more trucks, more troubles, More to check, CAMO



OR DO the MOD and always be in tune with your fuel supply. I have posted this before and for the 20 bucks to build it... it is a great piece of mind.



Patent pending, all right reserved, copy cat's allowed.

 

[TNDRIVER]

I have searched the forums but haven't seen anything like what I am experiencing. I have had this issue for a year and just can't seem to nail it down.

The issue is that it starts perfectly, idles perfectly, drives perfectly, accelerates and slows with zero issues, and does not overheat at all steady at around 220. The issue is when you drive it, it reaches operating temp, and you make it about a mile or two, maybe 20 minutes, it starts losing power and eventually stalls out and dies. Sometimes you can immediately restart but it does the same thing when you accelerate. If you wait a few minutes it will start right up drive about 100 yards then start the cycle all over again. I have replaced the fuel pump which was not putting out enough pressure, still the same issue. I changed out the thermostat because it was overheating before, still the same issue. I have replaced the entire fuel load with brand new fuel and changed the fuel filter twice, the same issue. I am at a loss please help...

Remove fuel tank and clean ( you are going to be surprised what is in there). REMOVE fuel filter housing and clean and replace fuel filter. Post a picture of the inside of your tank! If you have the inspection/fuel sender access plate in the bed pull that and then the sender and have a look around inside. My guess is the tank is coming off. (Sender is the round thing, 5 or 6 machine screws) Replace ALL of the fuel lines at this time and clean the check valves. If you are going to check the pressure try doing it right after it stalls, side of the road!!! or t the gauge in and drive it. I would look at the tank first. Two trucks, both tanks were a mess.

 

[Retiredwarhorses]

Fuel tank was no better

 

[Gunthar81]

Fuel tank was no better

That is what my fuel filter looked like first time I replaced it. Thinking the fuel tank is coming down as I am getting a pressure release when the fuel cap is removed after running it for a bit. Will update once I get it done.

 

[TNDRIVER]

Fuel tank was no better

YUP, about what both of mine looked like. Ran long enough for me to call rescue and have the kid tow me back ( I think he enjoyed it, laughed the whole time, 3 times)

 

[Retiredwarhorses]

YUP, about what both of mine looked like. Ran long enough for me to call rescue and have the kid tow me back ( I think he enjoyed it, laughed the whole time, 3 times)

this is algae....it will kill the injection pump. Your fuel filter probably is no good even now.

 

[Action]

HMMWV Troubleshooting Fuel System - Bing video

 

[Gunthar81]

SOLVED: So pulled the fuel tank and opened it up, all in all not too bad very little debris and almost no sludge. The strainer however was 100% coated and clogged.
So pulled the fuel tank and opened it up, all in all not too bad very little debris and almost no sludge. The strainer however was 100% coated and clogged. Replaced it, cleaned the tank put it all back together and within 30 seconds you could tell the difference in the amount of power, take-off time, and the overall difference in performance. Going to put in some injector cleaner and run about 10 gallons of new fuel through it, change the filter then call it a day. Now to replace the cooling lines. Thanks, everyone for the input and assistance.