6.5 Turbo Fuel System Diagnostics

[1151]

Thank you all for the great wealth of info on Steel Soldiers! Very great site and hope to contribute.

I recently received a new to me M1151A1 hmmwv with serial number less than 300k. I have read many TMs, watched videos, read the forums, etc.

I added 5 gallons of new diesel, it started for a few seconds then died but ran very rough. Have not been able to start it since.

The fuel filter was black and the finer filter in the middle was missing entirely. I have replaced both fuel filters with new ones. I filled the fuel filter assembly nearly full with diesel and diesel kleen before putting the top back on.

I have cranked the engine at least 50 seconds total over many ~10 second starting sessions (with 5-10 minute breaks in between) hoping to purge air and refill the fuel lines. Each time during / after cranking I can hear some kind of suction in the fuel filter area, and the suction stops about 10 seconds after stopping cranking. No fuel or air comes out of the fuel filter drain plug since replacing the fuel filters.

I pulled the fuel tank drain plug and a small quantity of thick red-ish oil slick came out before quickly transitioning to clear diesel. The red oil does not look like transmission oil, maybe super old diesel from the last time it ran?

I tried pressuring the fuel tank with air while cranking as shown in this thread without success (I used a jar lid with small hole in it for pressurizing). The tank is definitely pressurizing as it lets the air back out when removing the air gun or jar lid.

I pulled the fuel pump inlet and ran a clear hose straight into a clean container of diesel. The pump did not pull anything into the tube while cranking. This leads me to believe the fuel pump needs replaced.

With the fuel pump inlet disconnected I again pressurized the fuel tank expecting diesel in the line from the tank to the fuel pump to come out. Zero fuel came out. This leads me to believe the fuel tank and or fuel lines are badly clogged.

My next step is to replace the mechanical fuel pump / push rod assembly then test pulling fuel straight from a can of diesel (not the fuel tank).

I also need to drop / clean the fuel tank and lines.

Does this all sound reasonable? Am I overlooking anything? Are there any additional tests I should do before replacing the pump / dropping the tank? Are there any vacuum / vent gotchas that could invalidate any tests?

All feedback appreciated.

Thank you!

 

[Mogman]

Welcome to the forum!!


Before you condemn the tank/lines remove the check valves (2) in the fuel lines directly in front of the tank, these get stuck and prevent fuel flow.
Most just remove them and replace with a single piece of hose per valve (they are mounted inline with two short hoses ea. at this time), it does sound like the pump is also bad, probably no reason to replace the rod although it is necessary to remove it and coat it with grease to hold it up in the block, some will have other ideas that also work but that is what I do.

You may still need to pull the tank but I would try this first.

 

[GTUnit]

Dont remove the pump until you test it again. Hook up a piece of hose to the lift pump inlet and tan that into a gas can or small container with foretell in it, Run a clear hose from the pump outlet back into your container. Have someone crank the motor and observe.

If the pump is 10 years old i would change it regardless.