Trouble starting when hot
I own a 1991 F-Super Duty, 7.3 IDI, Over the last month or so I have developed a problem with the truck. When the engine is warm, the truck takes forever to fire. Truck acts like it's getting fuel or is fuel starved, but only when hot. truck starts normally when engine is cold, glow plugs come on, WTS light works fine.
I have good fuel pressure at the fuel filter, I know this because I pressed the schrader valve while it was being cranked and there was plenty of pressure.
The truck has had new injectors, MotorCraft Beru glow plugs, Glow plug controller just replaced two weeks ago to trouble shoot the problem.
I have never replaced the IP since I've owned the truck, I have no idea when the last time it was replaced.
Could it be one of the two switches or solenoids, what ever they are, on the IP?
Or possibly just be a IP that's tired.
If the truck sits long enough to cool down, the GPC will come on and the truck will start right up.
Hope this helps
to test it,next time this happens,pour a little lukewarm to mildly cool water over the ip.if she then fires right up,then you know for sure the ip needs to be swapped out.
ideally these engines need an ip and injector swap every 100k miles anyway.







