Archived 94 acting up again

[DU516]

I have a 94 2500 I recently replaced the lift pump because I thought it was bad. After that the truck ran good for about a week. Then my problem came back I was driving down the road

and the truck just shut off it restarted Fine I dove it home. The next day when I drove the truck to work it started fine I drove about 5 miles and then it did it again this time it was hard to restart when it started It ran rough like it was missing, so after about five more times on way to work of doing this It restated fine and ran fine the rest of the way to work. The next day I took the truck to the dealer, started and ran fine the whole way there.

They had it for four days they said that the fuel water separator was leaking and replaced it. I went to go pick the truck up and it wouldn't start. Finally it started I drove it about 20 miles and it shut off again hard to restart and then kept stalling out all the back to the dealer. When I got there it was running fine again. they had it another day and said they couldn't find anything. I picked it up it ran fine for 3 days then again last night it was hard to start and the ran rough then when I restarted it again it ran fine.



Please help I am so frustrated with this thing. I live in Delaware

if anyone knows of anyone or anyplace in the area that does quality work on diesels please let me know.

 

[B.G. Smith]

Shutdown

Sounds like the fuel solenoid might be bad or power to it from the switch is losing continuity. You might try removing the wire to it and installing a hot jumper and drive it. You will have to remove the jumper to stop the engine. bg

 

[Bob Horrell]

DU516,

My fuel solenoid did exactly as you describe before I finally replaced it with a cable. Every time I had a problem, I would troubleshoot to find out whether it was the solenoid or one of the relays and all always tested good. While it was intermittent and I was troubleshooting, I carried a piece of cut innertube (like a big rubberband) that I could use to hold the solenoid up so I wouldn't be stranded anywhere.

Finally I just gave up on finding the culprit and replaced with a PTO twist and lock cable from Napa. Their best cable assembly cost about $21 versus about $400 to replace the solenoid and all the relays involved. Now I have peace of mind and another anti-theft device, since most thieves wouldn't have a clue what the cable is for.

 

[Ben Rumson]

When your fuel shutdown solenoid is in the run position, the shaft on the bottom of it lifts up and rotates the fuel shutdown shaft towards the front of the engine - counter clockwise as you stand by the driver's front tire looking at it.



The Fuel Shutdown Solenoid has two coils inside. Once is a strong coil that is used to "pull" the shaft up when you first crank the key to the start position. The other coil is a weaker coil and is used to "hold" the shaft in the "run" or "up" position once the truck has started and it stay on "hold" while your driving. When you turn off the key, the "hold" coil disengages, the shaft falls, the shutdown lever going into the pump cuts off the fuel supply, and the truck shuts off.



If the "hold" cycle of the solenoid goes bad, it will let the shaft on the bottom of it fall down. This causes the fuel shutdown shaft to rotate back towards the firewall and shuts off the fuel supply.



Positive Battery goes to Fusable Link goes to 30 Amp fuel shutdown Relay goes to Fuel Shutdown Solenoid goes to Fuel Shutdown Shaft on the side of the pump.



If the Relay was going bad, it wouldn't start - but you could leave the key in the "on" position and lift the solenoid shaft by hand and more than likely it would stay in the "up" or "hold" position and you could then finish cranking the key over and start the truck. A bad relay generally won't shut the truck off while you're driving. But if the "hold" coils in the shutdown solenoid give out, then it would loose it's grip on the shaft, it would fall down, and the truck would shutoff - just like you've described. You might try replacing the relay, but from what you describe I would suspect that your problem is the solenoid not the relay.



My solenoid is going out and I have to lift the shaft by hand to start. I have a PTO cable on order as we speak and will completely remove the solenoid and use the cable to shut the truck down from now on (just like a tractor, older Mercedes, and lots of Diesels still do). I'm looking foreward to eliminating one more electrical component from the system.



In the mean time, you can attach a spring to your Shutdown Shaft to help hold it in the foreward or "run" position. Then if your "hold" coil acts up while your driving and trys to let go of the shaft, the spring will help hold the lever up and keep the truck running. If the spring is too strong, the shaft might now fall down when you turn the key off and the truck might not shut down. Be prepared to pop the hood on rotate the Shutdown lever towards the firewall to shutoff the fuel supply and turn the truck off.



If you do decide to replace the solenoid instead of by-passing it with a cable, PM me and I'll tell you where I found the least expensive solenoid. A cable will cost you under $30. A solenoid will cost you several hundred.



Hang in there.



- Ben