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Drops dead on acceleration when cold

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Old 10-21-2018, 05:18 PM
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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.
 
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Old 10-21-2018, 10:39 PM
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What is fuel pressure?
 
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Old 10-22-2018, 01:22 AM
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I do not know the answer to that question. Any FAQ on how to check this?
 
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Old 10-22-2018, 01:39 AM
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fordbozo if tomorrows no too busy I can stop by and check your fuel pressure.
 
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Old 10-22-2018, 01:55 AM
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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.
 
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Old 10-22-2018, 01:59 AM
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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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Old 10-22-2018, 03:24 AM
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There are two crew cab fords in Manzanita. I own one of them.
 
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Old 11-09-2018, 03:27 AM
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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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Old 11-09-2018, 09:46 AM
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Old Yesterday, 08:56 PM
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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.
 
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Old Yesterday, 10:10 PM
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Did you guys check out the Air Bypass Valve for proper operation?

What is your normal RPM at warm Idle?
 
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Old Yesterday, 11:26 PM
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Originally Posted by fordbozo View Post
Now that we've ruled out fuel pressure what's the next thing to check?
Pull codes. You want to know if the computer can see everything correctly or not, if it does then the problem has to be very basic(fuel, air, spark) or something that is messed up.... ex:EGR valve connected directly to manifold vacuum instead of to EVR.

 
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Old Today, 12:04 AM
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Originally Posted by fordbozo View Post
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.
So, "Used to have a real stumbling hesitation on acceleration now just flat dies."
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"?
 
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Old Today, 12:12 AM
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Originally Posted by fordbozo View Post
Now that we've ruled out fuel pressure, air temp sensor, coolant temp sensor, and main brain
It is not always true that the "New Parts" installation rules them out.
Have you compared the Resistance of the New and Old sensors?
Have you checked the supply voltage to the sensors?

 
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Old Today, 12:38 AM
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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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