1991 Ford Explorer Engine Wont Start (HARD ONE!)
Dirtymech
03-16-2006, 03:20 PM
1991 Ford Explorer 3.0 V6
After I replaced the head gaskets on this older model Explorer, it would not start. The battery is brand new and the starter motor turns the engine over at a quick pace, with the moving drive belts and obvious turning-over sound confirming this. But the damn thing will not start.
This vehicle is equipped with a Ford electronic distributor. I checked for spark at the spark plugs, and that was good. The fuel pump was very audible with the key in the accessory position. Checked for fuel to the cylinders from the EFI system by turning the engine over with no plugs. Plenty of vaporized gas built up on the spark plug hole threads. Even caused a small fire at one point cheking for spark/fuel. The Air Mass sensor has a good connection as well, and ther is no discontinuity in the flow of air to the intake manifold. I know the kind of trouble that can cause!
What could be causing this engine not to start? The thing I'd like to know is how does Ford's electronic distributor KNOW which turn of the camshaft the crankshaft is on? There's a crank angle sensor right at the crankshaft pulley, as on many Ford vehicles, but how would the computer know which turn the camshaft is on?
The reason I ask this is because the engine sounded like it backfired on two occassions, suggesting bad ignition timing. I did NOT have to touch the timing chain when replacing the heads, thankfully, so valve timing is the same since before I touched the car.
What about compression, also? I did a compression test and the results had a kind of big gap. The lowest cylinder was 105 PSI and the highest cylinder was 180 PSI. This might cause problems later, but would it cause the engine to not start at ALL?
Would really appreciate ANY help you can give. This vehicle has been a thorn in my side for a while now. Can't seem to fix it...going to try to read the OBD I codes with an analog voltmeter at some point...dont know if that will get me anywhere.
After I replaced the head gaskets on this older model Explorer, it would not start. The battery is brand new and the starter motor turns the engine over at a quick pace, with the moving drive belts and obvious turning-over sound confirming this. But the damn thing will not start.
This vehicle is equipped with a Ford electronic distributor. I checked for spark at the spark plugs, and that was good. The fuel pump was very audible with the key in the accessory position. Checked for fuel to the cylinders from the EFI system by turning the engine over with no plugs. Plenty of vaporized gas built up on the spark plug hole threads. Even caused a small fire at one point cheking for spark/fuel. The Air Mass sensor has a good connection as well, and ther is no discontinuity in the flow of air to the intake manifold. I know the kind of trouble that can cause!
What could be causing this engine not to start? The thing I'd like to know is how does Ford's electronic distributor KNOW which turn of the camshaft the crankshaft is on? There's a crank angle sensor right at the crankshaft pulley, as on many Ford vehicles, but how would the computer know which turn the camshaft is on?
The reason I ask this is because the engine sounded like it backfired on two occassions, suggesting bad ignition timing. I did NOT have to touch the timing chain when replacing the heads, thankfully, so valve timing is the same since before I touched the car.
What about compression, also? I did a compression test and the results had a kind of big gap. The lowest cylinder was 105 PSI and the highest cylinder was 180 PSI. This might cause problems later, but would it cause the engine to not start at ALL?
Would really appreciate ANY help you can give. This vehicle has been a thorn in my side for a while now. Can't seem to fix it...going to try to read the OBD I codes with an analog voltmeter at some point...dont know if that will get me anywhere.
sjwoody
03-20-2006, 07:20 AM
Try this thread on another forum....
http://www.ford-trucks.com/forums/showthread.php?t=454029&page=1&pp=12&highlight=timing
Read through all three pages. The fix at the end is surprising. Hope this helps...
http://www.ford-trucks.com/forums/showthread.php?t=454029&page=1&pp=12&highlight=timing
Read through all three pages. The fix at the end is surprising. Hope this helps...
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