Engine/Transmission (1994 - 1998) lift pump question

[JoshPeters]

I know there's a ton of lift pump problems, as usual, I have a goofy problem. If I just let my truck start on it's own, it'll crank over for about 8 seconds then fire. If I touch the throttle when I start to crank, it'll start right now, like half a second. The other possibly related problem is if I park the truck nose up. JohnE and others at the KDP/BOMB/BBQ last summer witnessed, it'll start right up, then die after about 20 seconds, hard restart, then run fine. I have checked the fuel return line, and it looks new, and replaced the overflow valve. The overflow valve helped it doesn't take as much cranking to get it to refire. The question I have, is this; Could my lift pump be sucking air? I would think if it sucked air, then uppon starting it would push the air through the lines till it was in the pump etc. I have noticed lately that my fuel milage is down about 1-2mpg no matter how I drive it. Last spring the timing was set at about 16. 5. The only change is I installed a torque converter. I noticed my milage dropping prior to the install, so I don't think that's related. Any ideas?



Josh

 

[Jeff H]

I asked this one quite a while back. My manual primer button leaks when I manually pump it. From what I was told that was nothing to worry about. Chances are if you are pulling air in through the lift pump. It will also leak fuel too. Not always.

Sounds like you have fuel that is being lost some where. Sounds like fuel could be going back into the tank some how. It could mean the lift pump may have a bad valve? If I remember right there are 3 check valves. 1 is overflow. 2Lift pump. Not sure but I think the fuel filter is too? Correct me if wrong.

I have a fuel leak at the pre heater bowl. It spit out lots of blue smoke when I start it. It starts a little harder. It runs rough for a few secounds.

Any blue smoke when you start it? Does it run rough too? If not my be a weak lift pump. Let it sit over night. Check pressure when you start it up. Should begin to build pressure after start up. Should take only a secound to start to build pressure. If the pressure takes too long it will eventually die.

 

[illflem]

You're confusing lift pump problems with 24 valves, 12s are very reliable.

Before throwing money at a lift pump best to check your fuel pressure.

More than likely you have a leak somewhere sucking air.

 

[Howard Durand]

I was reading an artilcle in the TDR where the pre-strainer/fuel heater should be checked and cleaned every 40K miles.

I am approaching 100K on my old 94 and have never looked at it but if you happened to get a slug of crud in your fuel, it could be a problem.