TowRig.com - Diesel Discussion and Tow Tech

I'm a little rusty on my Diesel troubleshooting knowledge, so I need some help with this one.

I have an '88 F-250 with the 7.3 NON-TURBO, non-Power Stroke, diesel. The glow plugs have never been replaced to the previous owner's knowledge, but it will start and run on the rear tank, the front tank being spotty. He's told me that I'd probably have to leave it running if I make stops, because it might not restart. He has been able to get it to start and run on the front tank, but it has a tendency to die.

Some jack-leg mechanic told him that the head gaskets were blown. I don't buy that for one minute. It only smokes a little on start-up, and it's white/blue smoke, not steam, which tells me its likely diesel smoke. Here's my question: Does it sound like this truck just has fuel pump issues? I know replacing the glow plugs will alleviate some of the hard start concern, but if I remember correctly, doesn't this thing have a low pressure pump in the tanks, and a high pressure pump that runs off the cam? Or am I thinking of the newer Power Strokes?

I had a '89 Ford F350 4x4 with 7.3 idi. Replacing the glow plugs will help the starting issue if they are bad. The controller relay could also be bad. Do you hear the controller cut in and out. If the controller short cycles, then some or all of glow plugs could be bad.

As to the fuel pump, there is not a pump in the tank, just the one on the side of the motor. Mine had the check valve go bad, allowing the fuel to leake back to the tank, making starting hard. The air had to be purged from the line before it would start. I added an electric pump in place of the mechanical pump and that ended the leaking check valve issue. The air would be purged while you waited for the Wait to start light. You could also have a cracked fuel line from tank to the switch over valve that could cause the front tank problem. Or the switch over valve could cause a simular problem if its leaking to the return line to the tank.

THanks. I'm in VA, but the truck is in Kansas. So I'm trying to troubleshoot it in my head before I get there, so that I at least have an idea of what to look for.

might even be as simple as the fuel filters if your lucky

If the controller short cycles, then some or all of glow plugs could be bad.


would this be like if the glow plug light shuts off after about 1 sec....?

mine has started shutting off waaay too soon and not heating up enuff..... I replaced the controller on the valve cover..... no help...... the old one does still click on and off (cycle)......are there any more relays or anything to check...?

Check the wiring harness on the passenger side fender well sometimes they go bad.I belive its number 129 if I remmember correctly.