1990 F150 (no start)

[glhs875]

I think the injectors are bank fired so each bank shares a power and ground. Ford service info doesn't go back to 1990 so I was looking at a 1992 but should be the same. Ford interprets crank rpm from the distributor and it is called a PIP signal. It uses pip to fire injectors. During cranking the engine light shuts off as soon as pip is received by the pcm

I checked the top lead coming out of the dist. module which I think is the pip signal. It was showing around 1100 rpm when cranking the engine. This thing has me puzzled. So far everything i have checked seems to be okay!

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I think the injectors are bank fired so each bank shares a power and ground. Ford service info doesn't go back to 1990 so I was looking at a 1992 but should be the same. Ford interprets crank rpm from the distributor and it is called a PIP signal. It uses pip to fire injectors. During cranking the engine light shuts off as soon as pip is received by the pcm

BTW,I really appreciate you helping me with this!

[glhs875]

How are the injectors grounded to the block. And I understand the injectors are grounded by the computer in order to pulse so how can they be grounded to the engine block also and not stay open all the time?

[RattFink]

No problem, I work on a lot of Fords! Sounds like you've covered all the bases here. The ford pinpoint test isn't very long on a no start and you've checked most of it. They refer to using a breakout box alot though. Do you have access to a scan tool for this truck?

[glhs875]

No problem, I work on a lot of Fords! Sounds like you've covered all the bases here. The ford pinpoint test isn't very long on a no start and you've checked most of it. They refer to using a breakout box alot though. Do you have access to a scan tool for this truck?

All I have is a code reader. If I can find my adapter i have a snap-on scanner, would that help?

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I wish I had a known good computer to try!

[RattFink]

The other thing is pcm power and grounds, if the pcm isn't even coming on then the injectors wouldn't pulse. If you could scan it then it'd verify the pcm. Is powering up and maybe could view rpm pid.

[glhs875]

The other thing is pcm power and grounds, if the pcm isn't even coming on then the injectors wouldn't pulse. If you could scan it then it'd verify the pcm. Is powering up and maybe could view rpm pid.

Would a snap-on scanner be capable of doing this test. Or how could I run an aux. wire to manually power up the pcm? Say straight from the batt. but to what wire on the pcm harness?

[glhs875]

How could I manually check (which wires/color) at the pcm harness for a 12V source and also to make sure the pcm has a proper ground?

[turbovanman²]

Snap On scanner is useless for a 90, you won't see much or any data. The computer grounds the injectors which is how they are controlled, in MS. If you had a labscope, you could watch the pattern. I know its a pain but you could have a shorted injector which would give you the problem your having. One side you can get to, the other, the upper intake has to come off. i am at work tomorrow so I can give you the wires to check for power and grounds. Use the headlight trick to verify grounds. IIRC, if your getting spark, the dizzy and module are fine.

[glhs875]

Snap On scanner is useless for a 90, you won't see much or any data. The computer grounds the injectors which is how they are controlled, in MS. If you had a labscope, you could watch the pattern. I know its a pain but you could have a shorted injector which would give you the problem your having. One side you can get to, the other, the upper intake has to come off. i am at work tomorrow so I can give you the wires to check for power and grounds. Use the headlight trick to verify grounds. IIRC, if your getting spark, the dizzy and module are fine.

Any info on the wiring would be great to have. So you think a shorted injector could keep all of them from pulsing?

[turbovanman²]

Yep, wigs the computer out and you get the condition you have. You could ohm test the ones you can get to today.

[glhs875]

Yep, wigs the computer out and you get the condition you have. You could ohm test the ones you can get to today.

I will look into that! Thanks for all your help!

[thefitisgay]

theres and eec tester plug... on my 92 l6 its under the hood pretty much right under the hinge on the fender... its under a little plastic cover that says eec test plug its got a spot for 6 wires but has 5 and theres a single wire in a single connector... you short certain wires or one to ground and then when you key on it will flash codes on the cel... they also have a running test.... google eec self test... i think the sho guide is the most informative? i forget sorry for not saying this first i feel like a doosh... good luck

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oh yeah drivers side fender... doh

[thefitisgay]

here http://www.scribd.com/doc/34996350/F...-and-Procedure

now i dont know if it will tell you any usefull information... or if you can even read the codes it give out bcause i never could (ha) theres like 3 different periods and no real seperator between them