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Ford expert
Ford expert, ASE Certified Technician
Category: Ford
Satisfied Customers: 10370
Experience:  30 yrs,experience shop owner,
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my 7.3L 1992 ford diesel is very hard to start when hot. easy

Customer Question

my 7.3L 1992 ford diesel is very hard to start when hot. easy start when cold
Submitted: 6 years ago.
Category: Ford
Expert:  Ford expert replied 6 years ago.
Welcome to just I'm here to help you and your 100% satisfaction is my goal. There are few different things that can cause this problem one being a lack of fuel the other being the glow plugs not operate properly . Start with checking the resistance of the glow plugs. When cold, the glow plugs should read about 0.5 ohms each. If they are more than 1.0 ohm when cold, they are faulty and need to be replaced. If the glow plugs show the correct resistance, check for any voltage drop between the glow plug controller and the glow plugs when the glow plugs are commanded on. If there is any voltage drop measured, repair the wiring as needed and retest. If all wiring and the glow plugs check OK, suspect a defective or incorrect glow plug controller.
Customer: replied 6 years ago.
the glow plugs are fine, in fact... if they were not they would'nt do such a great job on a cold start. There is no lack of fuel on cold starts... it turns over immediatly.
Is there anything that would block the fuel when hot?
Customer: replied 6 years ago.
Relist: Incomplete answer.
If you look at my reply to his answer, I don't feel that he fully computed the logic of his answer as applied to hot starts... The glow plugs work perfect on cold starts so they also work on hot starts. Plenty of fuel on cold starts so there must be something that prevents fuel coming in on hot starts until 30 - 40 seconds of grinding away as engine is trying to start... like just a drizzel of fuel coming in.
Customer: replied 6 years ago.

I've already tried all of the things you suggest and if cold starts are fine then something is preventing fuel from flowing on hot starts. Answer is incomplete.



Expert:  Ford expert replied 6 years ago.
Well I was hoping it would be something simple like glow plugs but from your description it appears you either have a faulty injection pump or low compression. I would do a compression test first if that shows a good than replace injection pump