My '94 turbo 7.3 idi died while running. It would not start. I strongly suspected it was a fuel problem. My batteries have been getting weaker, so I ran them down pretty quick. I charged them, hooked a bicycle pump up to the nipple at the top of the filter, pumped away with no change. Ran the batteries down. I took the filter/ separator off, replaced with new one primed with transmission fluid. Started right up, ran for about two minutes, shut off again. Ran the batteries down again. Took one battery out this morning, went to Wally world, they said the battery checks good.

If you could, help me identify the lines that run into the filter housing so that I can check the fuel pump. Am I using the air pump thing correctly? Also, I read a post that said there is a fuel selenoid that will shut off with bad batteries. Could that be the problem? Thanks!

 

All that did was pump more air into the system which will make it harder to start.... It's there to bleed air FROM the system and to check for fuel pressure from the lift pump. Crank it and then press the schrader valve in to see if any fuel comes out. If not, the lift pump is having issues. Or, how much fuel is in the tanks? If it's around 1/4 tank, the pickup may have broken off and is sucking air.

 

And if its cranking, you fuel solonoid should have enough power to stay on. I don't think thats your issue either.

I agree with lightning, The lift pump may be going bad but first check your fuel level. If it is a 1/4 tank, switch tanks or add a few gallons to eliminate a bad pickup tube. It is a common problem with these truck and mine has that problem.

I also 2nd the bycycle pump. that will just introduce air in the system. Like lighthing said, that is to purge air and check for fuel pressure. Not to pump the system full of air. I will push it if I run out of fuel so my electric fuel pump will purge out the air faster. You can also push it and if air comes out, then you have an air intusion problem.

 

What a concept, out with the bad air. I was listening to some bad advice from someone I thought knew. The theory was that the air would force the system to cycle fuel through the return line back to the tank thus purging air from the line.

So I assume that there is a gauge that I can attach to the valve to measure pressure. What would that pressure be?

I do run out of fuel at a quarter tank. I have to watch that carefully. But the tanks are almost full and I have switched tanks just to be sure.

 

The batteries are almost five years old, so they need to be replaced anyway. It does not take much to run them down. So I may go ahead and buy new ones.

Which line would I loosen to check the lift pump or is pushing the valve going to tell me?

 

Fuel pressure is only in the 4-8psi range. Harbor Freight has a cheap gauge that screws onto that valve. When cranking, you should be getting fuel out of that valve, not much, but some. May be time for an electric pump. I can get the facet Duralifts if'n you're interested.

 

I used a good dial type air guage for a tire pressure. (don't use the ones where the plastic slides out showing the pressure, the diesel will wipe all the numbers off)

Minimum pressures should be >2psi at Idle @ 675rpm and >1psi @ 3,000rpms. Not much pressure at all. Thats out of the service manual for the IDI fuel system check.



Just a thought and One more thing to add, I had a restriction in my auxelry fuel tank switch when i first bought it and It would start then die imidiatly. You can check for a restriction by buying a clear plastic inline fuel filter at parts store or walmart, like $3. When You put it inline before the liftpump in the rubber hose, If theres a restriction, it will suck the plastic fuel filter together and no restriction will flow free. You will also be able to see how much air is running though your fuel lines before your fuel filters. Great troubleshooting tool. The one I got was about 2" diamiter and 2 1/2 inches long (not including the nipples) and the fuel lines slip right on the nipples like an inline lawnmower filter. Mine sure sucked together telling me I had cloge in the line somewhere. Just an easy check that helped me isolate my problems. I also Have an electric fuel pump. They work great expecially when you run out of fuel, You can prime most of the system without having to crank it. Just turn the key on and hold the shreader valve until steady stream of fuel comes out without air. Then less than 20 seconds cranking will usually get it running again. (that is with good starter and batteries.


GENLIGHTNING, How do you like that tripple clutch torque conver. Can you feel a difference. thanks

 

I haven't had a chance to test it yet. Right after getting it running I had elbow surgery to repair a tendon, so it's mostly been sitting while I heal.
I have been able to do little things like modify the dash to accept the Ford tach and move some other gauges around. Another month and it shouod be almost done.

 

Follow up to my situation. I replaced both batteries. The truck started right up after pushing the Schrader valve a couple of times. I am no expert, but I think it was indeed the solonoid that cut the flow of fuel off because of bad batteries. Thanks for the help!

 

I am going to guess the engine cranked over much faster with the new batteries.

That is probably why it started right up.