Hmmwv. Not getting fuel (after new pump)

[Stuttgarts996]

Alright guys. Replaced my mechanical fuel pump after finding diesel in two hubs (truck ran fine though). This was last night. I let her idle for 5 min and drive a few 100 yds right after replacing . No issue. This am I started her up again and drove about an hr in stop and go traffic. After getting to work I shut her down came in for an hr then went out to move it. Upon start up she smoked white at ide but ran ok. Moved it to another spot and shut it down. Ten minutes later I restarted it and while running checked to see if any fuel would come out of the fuel filter petcock. As soon as I cracked it the truck died. Also no fuel came out. I then cracked the hard line at the mechanical fuel pump to see if it had fuel. Fuel seeped from the threads so looks like fuel is there. I did not do this while cranking though. I then removed the air screw from the filter housing and cranked 5-6 times for 10-15 second last each time but no fuel came from screw. I would assume that much cranking would have filled it? Any thoughts on where to go next. Hoping it’s something simple it’s my daily driver and I’m currently sitting at work . Needless to say until this gets sorted out I’m not going anywhere .

 

[Dock Rocker]

I am a little lost lost. How did diesel get into your hubs? How did you decide that it was your fuel pump that caused fuel to flow to your hubs and that it needed to be replaced?


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[Stuttgarts996]

Fuel pump is tied into the vent line. Torn diaphragm will allow fuel to back feed to the hubs.

 

[Stuttgarts996]

Is it possible that the pump push Rod could be out of place or damaged during install? Just trying to think of any possibility. I will admit I didn’t even think of it during the install. And did bump it over a few times to get the pump to seat enough for the threads to start.

 

[Dock Rocker]

Did you do the big glob of grease trick to hold the pump rod in place while you installed the pump?


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[Stuttgarts996]

Nope didn’t even think about it . Just placed it in and tightened it up . It almost looks like with the orientation of the fuel pump rod you wouldn’t even be able to get the pump in the whole street unless the rod was retracted in. As in I got lucky and when I was sliding in the pump i happened to catch the rod and push it up and the process . part of me is thinking about ordering a new pump rod and gasket kit before I pull this thing apart .

 

[Dock Rocker]

Nope didn’t even think about it . Just placed it in and tightened it up . It almost looks like with the orientation of the fuel pump rod you wouldn’t even be able to get the pump in the whole street unless the rod was retracted in. As in I got lucky and when I was sliding in the pump i happened to catch the rod and push it up and the process . part of me is thinking about ordering a new pump rod and gasket kit before I pull this thing apart .

If it wasn’t correct the pump rod will most likely come out in two pieces.


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[Stuttgarts996]

Way ahead of you. already ordered another pump in case I bent the arm, a new push rod and all the gaskets. I’m guessing the high-pressure pump had enough vacuum to pull the fuel through and keep it running because I was at more than idle most the way. I’m just open I didn’t do any damage running it lean for so long .

 

[snowtrac nome]

Is not the pump,you sucked air in when you opened the bleed screw. The rocedure for bleeding the system is remove the shut off wire and crank until fuel spits out,than you close the bleeder and hook up the fuel solenoid. Start,if there is air in the system when the solenoid has the rack open,you will get air in the high pressure lines,and also have to bleed them.

 

[Stuttgarts996]

Just cracked the output (metal line) on the pump and get a dribble while cranking. No measurable flow. Seems more likely to be the rod/pump I would think.

 

[snowtrac nome]

ill admit its been a while since I worked on hmmwvs but I always hated how long you had to crank to re fill the filters

 

[snowtrac nome]

Also you stated you cracked the line, when cranking the rack will be open so its going to try to fill the transfer pump a better test is to disconnect power from the fuel shut off than remove the line and check volume, pressure is only going to be around 5 psi.

 

[Stuttgarts996]

I cracked the line on the mechanical pump itself to verify any type of output.

 

[Action]

I am confused on yet another post. lol.
If the engine was starting and running, why were you opening things to see if fuel was coming out? (petcock, hard line at IP) Didn't you hear the engine running?

 

[Stuttgarts996]

white smoke at idle. If you read the first post that will answer your question.

 

[snowtrac nome]

Cracking the line wont tell you anything if the return is in play, remove the line ck pressure and volume its the only way you will get a good test.

 

[Stuttgarts996]

Roger that. Plan is to dig into it tomorrow after work.

 

[Action]

white smoke at idle. If you read the first post that will answer your question.

I did. Isn't white smoke a sign of unburned fuel? meaning, you had fuel.

 

[Stuttgarts996]

Black unburnt, white air in fuel/ lean I believe.

 

[Barrman]

Black is excessive fuel with the engine warmed up and under load.

white/gray/greasy smoke is unburnt fuel from a cold engine. Incomplete combustion in other words. Not firing on all 8 completely but fuel is there. The hazy smoke is normally a sign of bad glow plugs.

It reads as if you had it running fine until you let air into the IP by cracking the filter bleeder. Figure 30-50 seconds of cranking with fuel being pushed to the IP before the engine will fire again. Please, don't do this all one time. Crank for a 10 count, walk away and come back 10 minutes later, repeat.

But, then you wrote that even though the engine was running. You now have no fuel coming out of the fuel lift pump. How much fuel is in the tank? Have you pulled the fuel cap off to see if the tank was in a vacuum? Just listen for air trying to get in when you pull the cap. With the fuel cap off and the ignition wire removed from the top cover of the IP. Turn the engine over and see if you now get fuel spewing out of the lift pump out fitting. If so, plug the IP back in and do the 10 seconds at a time cranking exercise outlined above until it starts. If not, you might be swapping in another lift pump. Or have a problem in the tank/lines. Even a pin hole leak anywhere on the suction side will cause what you describe.

What brand pump did you install? Experience has forced many of us to realize if it isn't a new Delco lift pump. You might have gotten all the life out of the Chinese knock off part already.