hello everybody... I have a little trouble getting my '85 F250 diesel to start up
cold. I had started with fixing an electrical problem, the batteries would drain overnight, I fixed that by replacing the corroded battery cables. so the engine turns over fast when you turn the ignition on, starter is fine, glow plugs tested and working fine as well.

my problem seems to be something related to the fuelinjection system. I know that there are two pumps, one for fuel supply and one
that is the main injection pump. about the trucks behavior- it will start up only after some amount of turning over the engine, I only run the truck once a week, I use caution to not burn the starter motor out, turn the engine for 20 seconds then wait 2-3 minutes, try again and again until the engine finally comes to life after about four or five attempts like this. ( I should mention that it breathes out a heavy cloud of dark smoke when it finally starts)... it takes about fifteen minutes to get her to start, so this is not an optimal way to run the truck obviously and starter motor is probably not liking this... so I need to remedy the problem soon.

my theory is there is air getting into the system somewhere, I have used the check valve at the fuel filter to bleed the line while starting, this seemed to help. one guy I talked to suggested possible difference in fuel pressure on either side of the engine block could make for rough start-ups, and I have also wondered if the fuel injection pump needs replaced, but I don't want to throw money away if that's not really the problem... so that's all relevant info. I can think of at the moment, anyone have a suggestion? how to test the fuel injection pump to see if it is working properly? I welcome any advice anyone has to offer...

 

You're on the right track, but just need some direction. It is definitely an air intrusion problem. From the factory, there was a hose from the back of the filter mount to the return lines on the engine. If it is still there, take it off and cap the ends, this can be done by simply putting a bolt and clamp it in the hose. That actually is the International recommended fix, as IH Navistar did not put that hose on, only Ford did. Otherwise, look for any signs of leaks or cracks on the injector return lines. Any evidence of leaks there indicate trouble, and need fixed.