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Drops dead on acceleration when cold
1989 351w. New coolant temp sensor and air temp sensor and “brain.” Idles fine. Used to have a real stumbling hesitation on acceleration now just flat dies. Once it’s warmed up it runs fine. I’m slowly running out of ideas. Doesn’t throw a code. |
What is fuel pressure?
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I do not know the answer to that question. Any FAQ on how to check this? |
fordbozo if tomorrows no too busy I can stop by and check your fuel pressure.
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I’m in the valley this week, otherwise I’d be all over your offer. The other one is starting up a new schedule with school and it’s throwing a wrench in the works of pretty much everything. I never thought of fuel pressure though. |
I'm through your part of the woods twice a week, but Mondays would be the best. And I think I know where you live. You have most likely seen me, I drive a blue F-550 box truck with a flying W on it.
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There are two crew cab fords in Manzanita. I own one of them. |
I’m in Manzanita this weekend and all next week if I could throw myself on your mercy... 11-10 to 11-18 |
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With 892504x4's help, we figured out the fuel pressure was spot on, and not the cause of the trouble. Couple things happened while he was there that were a little strange.
Didn't start right up. That is pretty weird because it's been rock solid on starting. Died twice while idling. That is also pretty weird and I'd never seen this behavior before. I will re-classify this problem as a "stumble" on acceleration when cold. The engine speed drops, sometimes quite dramatically, on acceleration when cold. Now that we've ruled out fuel pressure, air temp sensor, coolant temp sensor, and main brain what's the next thing to check? 892504x4 suggested PIP or AFM? Another odd thing was when creating a vacuum leak it ran better when cold. |
Did you guys check out the Air Bypass Valve for proper operation?
What is your normal RPM at warm Idle? |
Originally Posted by fordbozo
(Post 18302437)
Now that we've ruled out fuel pressure what's the next thing to check?
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Originally Posted by fordbozo
(Post 18261752)
1989 351w. New coolant temp sensor and air temp sensor and “brain.” Idles fine. Used to have a real stumbling hesitation on acceleration now just flat dies. Once it’s warmed up it runs fine. I’m slowly running out of ideas. Doesn’t throw a code. When did you replace the 2 sensors and EECM? after the "stumbling hesitation on acceleration"? and the the result of changing those components was; it now "dies"? |
Originally Posted by fordbozo
(Post 18302437)
Now that we've ruled out fuel pressure, air temp sensor, coolant temp sensor, and main brain
Have you compared the Resistance of the New and Old sensors? Have you checked the supply voltage to the sensors? |
With the first cycle of the ignition fuel pressure went to 33 and held when we hit the no start the pressure was at 40psi and holding.
Here is what the info I have used to test the ICM. https://easyautodiagnostics.com/ford...module-tests-1 I can loan you my led test light on Thursday. |
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