I've got a 7.3 liter turbo, indirect injection on a 1994 F-350 crew cab. It's used to pull a gooseneck horse trailer, around 7,000 pounds. When I bought the vehicle last November the dealer replaced the injection pump due to surging and stalling at idle. The truck ran fine after that, maybe a little rough in the winter mornings when it was 3 degrees out but who's complaining.

Last month the rear tank started leaking so I pulled it. I don't know if that has anything to do with my current problems, but they started afterwards. For now I jumped the rear fuel line to the rear return line, I have a new tank but haven't put it in yet. The metal fuel lines are fairly corroded, though they've never seemed to leak.

Anyway, the problem with hard starting occurs after the truck has sat a while. It will start up, then cough and stall. Crank for 10 seconds, crank again for 10 seconds and it will start. I understand this is due to air leaking into the fuel filter, but I can't figure out from where. I checked the lift pump, it draws 15 inches of vacuum all the way back at the rear tank. I checked the fuel return lines on the injection pump and the injectors and they all look solid. I also pulled the return-line one way valve out of the fuel filter housing and turned the engine over to flush out any particles that might be in there but still no luck.

The second problem is surging at speed. It feels like somebody smacked it in the behind, it really takes off. Doesn't matter what speed you're running at, hot or cold. It's stalled at idle a few times as well. It's just like it was last November before the dealer replaced the IP.

The problems are gradually getting worse. Could the fuel tank, hard start and surging be related? Is the injection pump going bad? Would putting an electric fuel pump in help? Any suggestions on how to trouble shoot this would be appreciated. I mostly check my email at work so I may be a little slow to respond, but I really appreciate this forum.

 

i would check your glowplugs for the starting issue. my 93 turbo has 250k on it and starts everytime. had the injection pump replaced before i bought it.

I would also check your sediment bowl for water. if it has a good deal of moisture in it of if you haven't changed the filter in a year it would be wise to do so .

the surging, i'm not sure but i just posted something about a fuel pump relay on my 91 non turbo 7.3. just a thought.

good luck.

 

Visit..... http://www.intellidog.com/dieselmann/idi2.htm check out air leak points. Try removing the fuel filter before a start see if the filter is half full of fuel. Check the lift pump steel line end at the filter header and the filter header to IP steel line. there should be rubber seals under the cap nuts which will leak if not gently tightened or if they have deteriorated.

Check here for a pic..
http:///showphoto.php?photo=23223&pa...t=1&thecat=500

 

Thanks for the picture, I'll check those seals. I'm starting to wonder if the tank selector valve could be leaking a little air into the fuel line? Like I said, the rear tank is not installed right now and the problems started occuring after it was removed.

Could you steer me in the right direction with the motorhaven website? I checked but didn't see anything about air leak points.

Also, the fuel filter was the first thing checked. It did have a fair amount of water in it but it has a new filter in now.

Thanks again.
Will

 

If the problem started after the fuel tank was removed, it is most likely the selector valve. I had one leak between tanks. If you ran just one tank empty then switch to the other, it would slowly draw air from the empty tank and die. When you check your fuel filter, you should be checking for air. When you first loosen it off its mount, some fuel should weep out at the seal. If it doesen't, you already know it has more air than it should in the system. It doesn't take much air to give the hard start AND surging.