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Edward, ASE Certified Technician
Category: Ford
Satisfied Customers: 3023
Experience:  ASE certified. Auto Transmission rebuilder for Ford Motor Co. from 91 to 2000
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I have a 1987 ford f-150 with the 5.0 liter. When cold it

Customer Question

I have a 1987 ford f-150 with the 5.0 liter. When cold it runs rough,misfire,hesitation and poor idlr
JA: Is the rough idle intermittent or consistent?
Customer: consistent
JA: Are you fixing your F150 yourself? What have you tried so far?
Customer: plugs and wires fuel filter
JA: Anything else you want the mechanic to know before I connect you?
Customer: efi multi point
Submitted: 6 months ago.
Category: Ford
Expert:  Super Mechanic replied 6 months ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I am reviewing your question and will reply shortly, thanks.

Expert:  Super Mechanic replied 6 months ago.

Auto trans?

Are there any trouble codes?

There were some issues with them after a '4 hour soak'. Does that seem to be the problem? Hard start OR rough idle OR stalling.

Customer: replied 6 months ago.
manual trans This is on cold start up once it is warm the idle speed is inconsistant
Customer: replied 6 months ago.
no trouble codes
Expert:  Super Mechanic replied 6 months ago.

I see, thanks.

Let me just say that any money that you paid, or if you have a subscription, that money stays in your account until the answers are rated, (positive) regardless of how fast or how long it may take to get finished. You can FOLLOW UP AT ANYTIME, even after rating.

Most times if the ignition system is working good and the fuel pressure is up to specs. a cold running problem is either with the injectors, (starting to clog up),

However, I always clean the MAF sensor and replace the intake air charge/temp sensor, as they won't set any trouble codes and there really isn't a test for that.

Expert:  Super Mechanic replied 6 months ago.

Where did you go?

Customer: replied 6 months ago.
I don't think the 87 5L EFI used a MAF sensor I also have not been able to find the intake air temp sensor.
Expert:  Super Mechanic replied 6 months ago.

That is all the information that I have on it, but wait there may be another expert who has more. I will opt out and open it back up. Please DON’T REPLY to this post as that will lock the question back to me, also DON’T RATE THE ANSWER yet, someone should be along shortly, I’m sure, thanks and sorry I wasn’t able to help with it.





Expert:  Edward replied 6 months ago.

Hello, new tech here, does it smoke black out of the tail pipe when it runs rough, like it's running too rich? pull the vacuum line off the fuel pressure regulator, and tell me if you have any raw fuel in that line. Fuel pressure regulator is on the fuel rail and it's round and has a vacuum line going to it, also, check and make sure that hard plastic line is in good shape with no holes or cracks in it. Do you hae a fuel pressure gauge we can check the pressure with? If so you should have around 35psi, and when you nail the throttle or take the vacuum line off the regulator you should have around 40 psi then.

Customer: replied 6 months ago.
I will connect afuel pressure guage tomorrow after work. no black smoke, plugs are nice and grayish. I think it is running lean, it hesitates and misfires.I am also going to look for codes even though check engine light is not lite. Thanks Ken Larson
Expert:  Edward replied 6 months ago.

Alright Ken, let me know what you find with the fuel pressure. Thank you.