F150 Ignition Problem
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Joined: Jan 2004
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F150 Ignition Problem
I have a 1990 Ford F150 with a 302 and it recently started cutting out on me intermittently. It seems to happen when the engine is hot. The engine turns over but there is no spark. If I let is sit overnight, it will start again the next day. Two days ago, it cut out on me running.
I have done the following tests so far and am lost
1) Tested the coil. It is getting voltage and all the restistance measurements check out. 1.6 ohms primary resistance. Secondary resistance is 8.9K ohms. Both are in spec. Primary circuit continuity checks read 0 ohms from coil harness negative to ICM pin 2 and 3.9 K ohms from coil harness negative to ground.
2) Tested the ICM voltage supply. Here I am getting one strange reading 1.5 V off the #2 pin on the ICM. I think it's supposed to be 12. The number 3 and 4 pins both read 12 volts on Run and 12 volts on Start.
3) Tested the PIP stator sensor voltage and it reads 10.4 VAC which is a little above spec 3-8.5VAC though this could be my meter.
4) Tested the PCM module voltage and it is 11.8VAC which is also a little above spec 3-8.5 VAC. Once again, this could be my meter.
5) Pulled the distributor and ICM. Tested the ICM per Haynes manual and all resistances are well within spec.
I am at a loss here and would appreciate any help. Thanks.
Basil...
I have done the following tests so far and am lost
1) Tested the coil. It is getting voltage and all the restistance measurements check out. 1.6 ohms primary resistance. Secondary resistance is 8.9K ohms. Both are in spec. Primary circuit continuity checks read 0 ohms from coil harness negative to ICM pin 2 and 3.9 K ohms from coil harness negative to ground.
2) Tested the ICM voltage supply. Here I am getting one strange reading 1.5 V off the #2 pin on the ICM. I think it's supposed to be 12. The number 3 and 4 pins both read 12 volts on Run and 12 volts on Start.
3) Tested the PIP stator sensor voltage and it reads 10.4 VAC which is a little above spec 3-8.5VAC though this could be my meter.
4) Tested the PCM module voltage and it is 11.8VAC which is also a little above spec 3-8.5 VAC. Once again, this could be my meter.
5) Pulled the distributor and ICM. Tested the ICM per Haynes manual and all resistances are well within spec.
I am at a loss here and would appreciate any help. Thanks.
Basil...
Member
Joined: Jul 2003
Posts: 19
Likes: 0
From: Georgia
it looks to be a temperture related.I had a old f100 that was doing something similar...think it turned out to be the distribitor..ohm good while cold warmed it up with a heat gun and it checked bad..recheck your voltages/ohms after components has been warmed up and see what you get
Senior Member
Joined: Feb 2001
Posts: 776
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From: Guyton, GA USA
Country2 could be right. I had a Honda that had the same problem. When it was cold it would start right up, but if it got too hot when you were driving it, it would shut off. You'd have to wait about 30 minutes and start it up again. Turned out to be the ignition module in the distributor.
Senior Member
Joined: Feb 2003
Posts: 755
Likes: 0
From: So. California
Temp is the problem especally if you have the module mounted to the dist. Later EECIV 's' mounted the module to the back side of the radiator. The module is famous for developing an open in the circuitry when it get hot. You can sure go ahead with the blow dryer ( heat gun might be a better test) or you could replace the pick up and module. This is one time when replacing parts will probably save you a lot of Diag, time and headaches