1991 f150 no spark 5.8 EFI guru needed

[ippielb]

they have a rating on them like any fuse, so replace with the same size wire and amp rating and your golden

So basically to test, just check for ohms on either side of the fuse link, or do I have to have key on and check for 12v.

 

[Clode]

Hard to check that when I'm trying to work on the truck solo. So can't really tell.

How much is involved to changing ignition switch on these trucks.

To check spark I have had to use an inline spark tester with alligator clips to the negative battery post, and reach the ignition and hold a mirror on a piece of steel and hold it out to look around the hood to see.

when you go to crank make sure the fuse box stays powered up on the injector fuse/fuel pump fuse etc, you can do this alone and crank

 

[Clode]

So basically to test, just check for ohms on either side of the fuse link, or do I have to have key on and check for 12v.

just ohm check, should be almost 0

 

[ippielb]

when you go to crank make sure the fuse box stays powered up on the injector fuse/fuel pump fuse etc, you can do this alone and crank

I'll have to go check if there's a fuse for that under the column. I guess I should check the eec relay as well, so many wires and relays by the air box...

Got some stuff to check, I'll head out to the shop and check and get back to you guys.

 

[ippielb]

Well, tested the relay for the eec, tested out good, checked the ICM's and it tested out good, then tried to test the crankshaft positioning sensor, and it isn't sending a signal.

Had power to everything, and Eli for when testing while cranking and while it was turning over it dropped down to 8-9v.

The coil only flashes a spark on my tester when I ground it to the intake manifold,and it only flashes when I start cranking and when I turn the key off from cranking. Nothing while its cranking.

 

[daddys girl]

so did you ever check to see if the distributor is actually turning.could be a broken timing chain or the pin that holds the timing gear.

 

[ippielb]

so did you ever check to see if the distributor is actually turning.could be a broken timing chain or the pin that holds the timing gear.

Distributor is spinning, I had to take the distributor off to change the crank positioning sensor. Pins are intact, and gear clean and in good shape. Marked very well before and crank set to Tdc on cylinder one. Everything put back together, and rotor spins when crank turns.

 

[JMCX]

maybe check the fuse links over by the battery, they may be in the loom, they like to fail also

http://i1252.photobucket.com/albums/hh570/cbakker1/null.jpg

Turn the ignition key to run. Find this starter solenoid by the battery. Crank the engine from under the hood by shorting the battery side big lug to the post with the small red wire.

 

[ippielb]

Turn the ignition key to run. Find this starter solenoid by the battery. Crank the engine from under the hood by shorting the battery side big lug to the post with the small red wire.

Sorry didn't quite understand, I have jumped the starter solenoid with a booster cable and it still turned over with no spark. What am I suppose to do with the smaller wire on the "S" terminal on the solenoid?

 

[JMCX]

Sorry didn't quite understand, I have jumped the starter solenoid with a booster cable and it still turned over with no spark. What am I suppose to do with the smaller wire on the "S" terminal on the solenoid?

The 'S' wire is what you're energizing when you turn the key all the way to the crank position (activating the starter solenoid). If there is an issue where the ignition system isn't getting power in the crank position this will eliminate that problem. Remember the key has to be in the run position for this to work. Also, you can more easily watch for spark. Put your spark tester right on the coil wire.

 

[ippielb]

The 'S' wire is what you're energizing when you turn the key all the way to the crank position (activating the starter solenoid). If there is an issue where the ignition system isn't getting power in the crank position this will eliminate that problem. Remember the key has to be in the run position for this to work. Also, you can more easily watch for spark. Put your spark tester right on the coil wire.

So basically jump from the positive battery post to the "S" terminal to turn it over? I was just taking the cable that goes to the starter and unhooking it to go directly to the battery. Turned over great but still no spark. I'll try your method tomorrow if I get time, going to be super busy it's suppose to rain starting tomorrow for 3 days and we have LOTS to do on the farm.

I have put the spark tester everywhere and still cannot get any spark.

 

[Lund]

Well, tested the relay for the eec, tested out good, checked the ICM's and it tested out good, then tried to test the crankshaft positioning sensor, and it isn't sending a signal.

Had power to everything, and Eli for when testing while cranking and while it was turning over it dropped down to 8-9v.

The coil only flashes a spark on my tester when I ground it to the intake manifold,and it only flashes when I start cranking and when I turn the key off from cranking. Nothing while its cranking.

While CRANKING you need 12v at pin #4 or the spark won't happen.
If you don't you will get the red highlighted symptoms your getting.
Plus you should set your spark tester at coil and not ign wire end when checking for spark.

 

[daddys girl]

If you have spark the the coil should be good,so maybe the hall effect switch is bad and not sending a signal to the modual.

 

[lloydguy]

Your ignition switch harness should have
2 yellow's that are both constant 12V
2- grey/yellow stripe that are IGN 2 ,only live in run position.
1- red/light green stripe that is IGN 1 , live in run position and during crank ( if this wire is not 12v during crank you will NOT have spark)
You will also have Black/light green stripe but that's just accessory wire.

 

[JMCX]

Maybe some mice were munching on your wiring. You could also try putting 12V directly to the + side of the coil from the battery and see if that makes any difference. The module switches the -neg side to create the spark.

 

[ippielb]

http://www.therangerstation.com/tech_library/images/TFI_Labels_resistancetest.gif
While CRANKING you need 12v at pin #4 or the spark won't happen.
If you don't you will get the red highlighted symptoms your getting.
Plus you should set your spark tester at coil and not ign wire end when checking for spark.

In that picture, I have no signal from #6 wire PIP sensor, or the crank sensor depends what you want to call it. Test light never lit up, or the multimeter never got any current.

#4 has power while cranking, but it drops down to 10v while turning over.

 

[ippielb]

Your ignition switch harness should have
2 yellow's that are both constant 12V
2- grey/yellow stripe that are IGN 2 ,only live in run position.
1- red/light green stripe that is IGN 1 , live in run position and during crank ( if this wire is not 12v during crank you will NOT have spark)
You will also have Black/light green stripe but that's just accessory wire.

There's one website that I used that showed how to test the IGM and the Coil, basically the whole ignition system. I everything tested out good, except the fact that I never had a signal from the PIP sensor.

 

[ippielb]

Maybe some mice were munching on your wiring. You could also try putting 12V directly to the + side of the coil from the battery and see if that makes any difference. The module switches the -neg side to create the spark.

I'll try that tomorrow morning before work.

 

[lloydguy]

Sound's like you've got alot of hour's into it already, but sometimes wire by wire is the only
way to find the one that is giving you the problem.PITA, but good luck.

 

[ippielb]

Sound's like you've got alot of hour's into it already, but sometimes wire by wire is the only
way to find the one that is giving you the problem.PITA, but good luck.

Oh you bet, distributor off 3-4 times double checking the cam gear, and then check the stupid ICM cap has been off 50 times, the coil connector is going to be worn out from testing. I'll need a new battery after I'm done, and I took about 10 years out of the starters life time haha