Spark Issue

1995 FORD F150

MEMBER
1995 FORD F-150
5.0L
V8
4WD
MANUAL
265,000 MILES

It will turn over and sometimes run for a few seconds but it misses really bad. It broke suddenly while I was driving it. I have checked the timing chain and it is fine, I have checked compression and 7 of the cylinders had a solid 130 psi and cylinder #7 had a max of 90. I believe it may be an ignition coil or a spark issue but I am not sure. Any ideas?

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5 Replies

HMAC300

MECHANIC
48,601 POSTS

If you have 90 on one cylinder an d130 on others then it is a valve problem. Like burnt or bent or valve spring so check those first. It will continue to miss until the valve or compression problem is fixed.

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Thursday, March 30th, 2017 AT 6:38 AM

1995 FORD F150

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2 POSTS

We checked the valves on the cylinder with low compression but they look fine. I'm wondering if it is the distributor because I've heard that wet weather can mess those up.

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Friday, March 31st, 2017 AT 8:06 AM

HMAC300

MECHANIC
48,601 POSTS

Take the coil wire out and use insulated pliers try starting truck and run the wire around the top of coil see if it jumps anywhere other than the end of wire if it does it's cracked. then check inside of cap for moisture but if it starts without doing that I kind of doubt it's the dist cap. have you checked all the fuses under hood? also what is fuel pressure with a gauge? it may be a fuel problem not spark. a car will quit while running and seem like electrical but its' not. Is check engine light on? see link for fuel pressure auto parts rent gauge....
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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Friday, March 31st, 2017 AT 8:11 AM

1995 FORD F150

MEMBER
2 POSTS

The truck has two tanks with two fuel pumps and we have tried both tanks. I will try and measure the fuel pressure tho. No check engine light but the former owner may have disconnected that. I will check the fuses. Do these trucks have an obd?

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Friday, March 31st, 2017 AT 8:26 AM

HMAC300

MECHANIC
48,601 POSTS

Yes it is obd 1 I think if it's obd2 it will have a 16 pin(hole) connector. I am also sending on how to diagnose with 2 tanks to see if you are getting fuel etc. Also with key on only you should have 35-45 psi at fuel rail auto parts rent gauge

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