GEM PROBLEM

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Oct 12, 2010 | 10:53 AM

dirtmonkey11

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GEM PROBLEM

I have had a problem with my gem module in my 2000 5.4 Expedition. The truck won’t start when it’s cold outside, cranks but no start. It has fuel pressure and holds it. I am almost positive it’s the GEM or a connection going to it because I would move the wires around and lightly tap the GEM module and the truck would start no problem. Does anyone know what is causing the problem or what could I check to find the problem. I hooked up a scanner to check for codes, there are none. All the data from the pcm is normal. Could temperature affect the operation of the GEM and if so what would be the fix. I have heard of the water leaks onto the GEM, which I will be checking into but the problem mainly happens when it’s cold, it hasn't rained in 2 weeks and my truck wouldn’t start. Any information on this problem would be appreciated.

Oct 12, 2010 | 07:19 PM

projectSHO89

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From: St Louis

The GEM is not associated with any functions that would cause a "Crank but no fire" symptom. More likely, it's a connection problem in the CJB.

Oct 12, 2010 | 08:01 PM

alloro

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From: 0,0,1

Quote:

Originally Posted by dirtmonkey11

I would move the wires around and lightly tap the GEM module and the truck would start no problem.

This defines your problem as an electrical connection one. The GEM and the fuse box have to come out to be inspected for rust or corrosion at their connectors.

Oct 15, 2010 | 10:24 AM

dirtmonkey11

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UPDATE: I pulled off my lower dash panel to get a better look at the fuse block and the GEM. I started to manipulate the wires a little bit and went to crank it and it was trying to fire, it would catch but never fire. I'm pretty sure that it’s a connection issue. The only think I wasn't sure of is, how common are the water leaks on the Expeditions that leak onto the GEM or fuse block area. I have read some different post as well as bulletins from Ford explaining the problem. Does anyone think that my problem is related to a water leak corroding the connecters?

Oct 15, 2010 | 11:43 AM

pdqford

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From: Central NYS

I'm asuming that your CEL lights up when you first turn the key to the "ON" position. But when you turn the key to the "START" position and the engine begins to crank, does the CEL light stay on or does it turn off while it is cranking and not starting?

Oct 17, 2010 | 01:48 PM

dirtmonkey11

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I'll check today, what would that indicate if the light stays on, would that be the cam position sensor, meaning the pcm not getting a reading from it.

Oct 17, 2010 | 04:08 PM

pdqford

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From: Central NYS

Quote:

Originally Posted by dirtmonkey11

I'll check today, what would that indicate if the light stays on,

That is an indication that the PCM has not yet seen a CKP (Crank Position) sensor signal.

(I know that was the case with the old EEC-IV systems, and hopefully they kept that in the new systems. Let us know what you find.)