benroberts3605

A guy at work has a 96 12 valve that will run for a while then die. he was telling me that his has a manual primer for the pump he can do that and it will re-fire then die shortly after. all the air is out of the system. i was thinking it is the pump. any ideas?

infidel

Sounds like the shutdown solenoid isn't staying up.
You could tie it up in the run position with some wire or a cable tie and see if things change.

high bid

not to change the subject but wow, I noticed you have one of those converted 350 gm diesel! My mom had one...great mpgs and ran great up to about 250k miles....I guess that was pretty good for a gas converted diesel.

benroberts3605

thank you vary much i will tell him

benroberts3605

and yea that old cady is super slow but it just runs and runs, its getting a cummins one of these days

RCW

If the shut-off solenoid is not the problem, check the fuel heater for an air leak at the electrical connector.

Another common problem is the flexible fuel lines. There are two from the frame hard lines to the engine, one by the transfer (lift pump), two from the tank to the frame hard lines, and a stinker in the fuel tank.

The guy in the fuel tank will give the exact symptoms your friend is having, but if the tank is full the symptoms go away.

Of course there is the usual filter issues of leaking, a drain left open, etc. Then there is the overflow valve on the inside of the pump, where the fuel return line connects. If that spring breaks you can get a short run then die, and have to reprime.

If he is able to reprime using the transfer pump button, it is unlikely that pump is bad. If the truck starts once primed, it is unlikely the injection pump is bad.

benroberts3605

thank you sir i will be passing this info on in the A.M.

Don.44

I have a 99 Dodge /Cummings and the engine goes into safe mode while driving If i let up on the pedal and coast for a second then hit the throttle again it runs fine until the next time . Any ideas ? What is the symptom of a bad transfer pump ? Could it be an air leak ? Truck ran fine then I laid it up for 6 months inside a shop and this started . The truck only has 50,000 miles .
Your thoughts would be appreceated
Don

BigIron70

Rotted out fuel hoses possiblle sucking air into fuel system or mechanical fue pump went out. Hook up fuel pressure gauge and see what you have for running pressure. 20psi is normal pressure. If lower pinch off return line (smaller hose) if fuel pressure goes up then overflow valve is bad (weak spring). Common problem if you never had fuel lines replaced yet. They run up over bell housing area left side of engine.

Don.44

The transfer pump that draws fuel from the tank to the lift pump should have 20 pounds pressure ? A while back I was told that I should install a low pressure electric fuel pump before the mechanical transfer pump. That should eliminate any peoblems but if I continue to drive it like this I could ruin the injection pump. The fuel lines rotted out is a good possibility I should check closer . I was thinking it could be not the right amount of fuel getting to the lift pump. I will take your advise and check the pressure . Do the new ones use an electric pump in the tank ?
Don

patdaly

Don, you are being confused with a 12 valve truck. Typically you don't want more than 14 or so PSI with a 24 valve, and you have no mechanical pump. Yes, if your lift pump has died, it can and will kill your VP ( Injection pump ), that being said, I don't think this is your issue. Fuel or air leaks typically begin with a hard or no start issue, not dead pedal ( what you have described ). I am more of a 12 valve kind of guy, so you may want to do a search here on dead pedal or APPS reset.

I think you will find your APPS ( throttle position sensor ), or VP 44 is on it's way out. If you find it is the APPS, check out the TIMBO APPS thread on here, it works well by all accounts, and is much, much cheaper.

Lift pump went into the tank with the 2004.5 trucks, and the dealerships try and convert any old ones, some of us try and convert all we can back.

Don.44

You are right my truck is a 99 but it has no pump in the tank because I had to change the sending unit a few years ago . It wasn't there . It must have a transfer pump on the motor some place to put the fuel to the lift pump . I have no codes showing but the acclerator will go dead as you say If I lift up on the acclerator it will pick up the fuel and I can go again. Could it be the map sensor ?I have no codes to check ?
Don

patdaly

Yep, your Lift pump is on the block, drives side, electrically driven. You need to have it scanned for codes if you haven't, check engine light won't always come on.

I will have to defer to the 24 valve guys, post on that subforum, I am sure they will hop in. Most of us are stuck past using duct tape to fix something.....

9812vram

Actually, it's quite the opposite... The Primer is independent of the transfer pump in operation. Transfer pump can be pooched and the primer will still work - IF the inlet check is still working. If the primer pumps fuel (in this case it does) then the inlet check is good, which means there's a very good chance the transfer pump is toast.

My money's on the pump.

Don.44

Would the electric transfer pump fill the fuel filter ? In this case it doesn't seem to fill it after it was changed or can I feel any air come out of the holes on top. I had the helper fill it with fuel in the plugs on top . Then the truck started .

Don