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Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, Tech Trainer
Category: Ford
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I have a 1989 Ford E350 with a 460 it starts and runs fine a

Customer Question

I have a 1989 Ford E350 with a 460 it starts and runs fine for about a minute then It starts running bad when you step on the gas it sputters and breaks down still runs but no power I thought it mite be the ECM or ECU witch it is called I don't know put I cant see how to get it out from under the heater box could this be my problem and how do I get it out ?
Submitted: 6 months ago.
Category: Ford
Expert:  Jeremy replied 6 months ago.

What makes you think it is the PCM? Did you check all the other items like fuel, plugs, distributor, coil, etc?

Customer: replied 6 months ago.
That is what someone told me that is why I am here
Expert:  Jeremy replied 6 months ago.

I was only asking to see if you did other tests to narrow it down. Were other tests done yet? Like checking fuel pressure? Were the plugs pulled and inspected? What about the distributor cap and rotary? Air filter checked for blockages? All the other basics? I would rule those items out first.

Pull the pcv valve and see if it's plugged. Ise a smoke machine to check for vacuum leaks.

The reason is because the PCM rarely is the cause of the issues. They do go bad, but rarely.

Customer: replied 6 months ago.
Plugs are new Cap looks good Have not checked fuel pressure yet don't know how to check coil .
Expert:  Jeremy replied 6 months ago.

Use a spark plug tester on the wire from the coil and see if it is sparking.

Customer: replied 6 months ago.
Sorry I only get to my email at night the truck will start and run so I am assuming the coil is working it starts to have problems
after it starts to warm up then I push on the gas it starts to brake down and no power .
Expert:  Jeremy replied 6 months ago.

I'm going to opt out so one of the night experts can assist.

Expert:  cardoctor74 replied 6 months ago.

Different expert here is the check engine light on?

Customer: replied 6 months ago.
No Check engine light was doing fine was driving and it just happened .
Expert:  cardoctor74 replied 6 months ago.

Ok does the engine light come on then go out when you cycle the key ?

Customer: replied 6 months ago.
Sorry had to walk out to the truck the check engine lite does not cycle it comes on when you turn the key on and dose not go out but when you start the truck it go's out .
Customer: replied 6 months ago.
Hello what happened
Expert:  cardoctor74 replied 6 months ago.
Ok that's normal operation then.How many miles on this truck ?
Customer: replied 6 months ago.
Your back I was wondering what happened to you It has 128,234 miles and yes that is original miles
Expert:  6Bucs replied 6 months ago.

Does the oil pressure gauge work?

Customer: replied 6 months ago.
It is almost at the center of the gauge
Expert:  Juan Crespo replied 6 months ago.

Hi there. Different expert here.

The truth is that if you want to work on your own vehicle, you got have the essential tools that would allow you to do so. For this particular symptom, where it starts and runs OK and then sputters and breaks down, the first thing you need to do is measure fuel pressure (fuel pressure testers can be borrowed from most of the major auto parts retail stores). If fuel pressure is 35-45 psi when the engine is first started, but then starts going down, then the fuel pump or pumps need to be looked at.

If fuel pressure tests OK. Then the other test associated with these symptoms is to measure engine vacuum (vacuum gauge/pump tool also available at most auto parts retailers). An engine that is "breathing" normally would have anywhere from 18 to 22"Hg at idle with all accessories off. To test how your van is breathing, first connect the vacuum gauge hose to any manifold vacuum port (use the "tee" fitting provided with the tool if necessary). Start the engine and record vacuum reading on the gauge. Leacve the engine idling while you go and have some coffee. After 15 minutes or so, come back and check vacuum. If lower than before, there is an obstruction in the exhaust system that needs to be repaired.

Please let me know what you find.

Expert:  Juan Crespo replied 6 months ago.

Hi there. Different expert here.

The truth is that if you want to work on your own vehicle, you got to have the essential tools that would allow you to do so. For this particular symptom, where it starts and runs OK and then sputters and breaks down, the first thing you need to do is measure fuel pressure (fuel pressure testers can be borrowed from most of the major auto parts retail stores). If fuel pressure is 35-45 psi when the engine is first started, but then starts going down, then the fuel pump or pumps need to be looked at.

If fuel pressure tests OK. Then the other test associated with these symptoms is to measure engine vacuum (vacuum gauge/pump tool also available at most auto parts retailers). An engine that is "breathing" normally would have anywhere from 18 to 22"Hg at idle with all accessories off. To test how your van is breathing, first connect the vacuum gauge hose to any manifold vacuum port (use the "tee" fitting provided with the tool if necessary). Start the engine and record vacuum reading on the gauge. Leacve the engine idling while you go and have some coffee. After 15 minutes or so, come back and check vacuum. If lower than before, there is an obstruction in the exhaust system that needs to be repaired.

Please let me know what you find.

Customer: replied 6 months ago.
OK thank you I will do these test I do have the tools to do this I just needed info that the books at the auto story do give you I will let you know how it go's you gave me more info in one paragraph than all three of the other guys did thank you .
Expert:  Juan Crespo replied 6 months ago.

Looking forward to hearing from you.

Best Regards.

Customer: replied 6 months ago.
Sorry it took so long to get back to you heavy work load this week ok we have checked the fuel rail psi is steady at 42 at idle and as we increase the rpm it stays the same and the vac. is holding at 20 it runs fine at 700 rpms and as you go u to 1100 it then starts to brake down .Thank you
Jim
Expert:  Juan Crespo replied 6 months ago.

Hi Jim,

I don't usually work on weekends, but I had to check a few things on the site and happened to see your reply.

I'm a bit confused by your post: Are you saying the fuel pressure stays the same at idle than it does as RPM increases? If so, there is something wrong; fuel pressure should rise as throttle is opened and vacuum to the fuel pressure regulator decreases. Also, vacuum should change as throttle opens, not hold steady.

Another thing that's a bit confusing: are you saying vacuum was 20 inches at idle and stayed that way after the engine had been idling for 15 minutes?

Is the engine "braking down" in Park or under load in gear? Does it run better if you spray carb cleaner through the throttle?

I'm afraid I won't be able to check on your reply until next Monday when I log in at 2PM EST. Hope to read your reply then.

Have a great weekend!