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91 Explorer cranks but won't start after head swap

JTravis

Member
Joined
July 4, 2006
Messages
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City, State
Waverly, TN
Year, Model & Trim Level
1991 Explorer 2wd XLT
Hi, all. I've got a mystery that would confound Scooby-doo AND those meddling kids. I've got a 1991 Explorer XLT 2WD 4.0 that had a cracked head but was still running when parked. I got a brand new pair of heads and gasket set from Alabama Cylinder Head, and installed them along with new head bolts and top end gasket set, new o-rings on the injectors top and bottom, a new O2 sensor and new crankshaft position sensor.

Despite all the above, now that it's all back together, it will crank and crank, but it won't start. The fuel pump is pumping up (I can hear it run) and I even went so far as to swap out the coil pack with a good one from my 1994, and still nothing. I took off the intake hose and sprayed a little throttle body cleaner into the manifold past the throttle plate, put the hose back on and cranked, and STILL nothing, so I am thinking no spark (as that would have at least tried to fire even if the injectors were not getting a signal). I know the crank position sensors have a bad rep on these trucks, but that's already been changed. I checked the fuses in the underhood panel, and they are good.

I'm about to the bottom of my bag of magical tricks to make it go... :rolleyes: Any ideas of what I might be missing? Short of killing a chicken at midnight and doing a VooDoo dance, I'm fresh out of ideas. :eek:
 



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Don't call the gris-gris man yet.

Disconnect battery for 10 minutes to reset everything, it should have been disconnected during the head change. Is the CEL light on?

Push the schrader valve on the fuel rail to establish fuel's at the rail. WEAR EYE PROTECTION!

When vapor is cleared, pull a plug and look for spark with a spark (ignition) tester.

That will narrow down the problem. If spark is problem, check for good connection on the CPS connector.

If spark and fuel present, check the coolant temp sensor, that's been identified as a start problem.
 






I had the same problem, someone on the forum said I should recheck the sparkplug wires ( :thumbsup: big ups to that guy ). I did, felt dumb, but that was the problem.
 






I had the same problem, someone on the forum said I should recheck the sparkplug wires ( :thumbsup: big ups to that guy ). I did, felt dumb, but that was the problem.

It aggrivates me to death when i do that....

Looks like you have a few good ideas already. I would try them all.
 






I appreciate all the help and advice. Here's the latest in this fiasco- Checked fuel pressure; that's good at the rail. Disconnected and reconnected after 10 minutes; no change. I checked the coil with an extra plug wire and plug held to the block; no fire when cranking. So I checked the hot wire to the coil. No power to it. Checked the hot wire to the ignition module. Got power there. Changed module to one I know is good off my 1994. Still nothing. Jumpered the hot from the module feed to the coil hot wire where it also goes to the condensor. Still no fire at the plugs when cranking. Next step, I suppose, is to check for power going down to the new crank position sensor. What should I check for on the coolant temp sending unit?
 






The wiring diagram for my '92 shows that the "hot wire" to the coil comes straight from the ignition switch, and not through the ICM. You have power at the ICM, so we'll assume that you have power to the EEC relay and that it is closing properly, which also suggests that the ignition switch is closing properly. That suggests to me that you have a break between the ignition switch and the coil.
 






Wiring Diagrams: They're for a 93 but I think its the same...

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-Ted
 






Ignore the cooling temp sensor, it only is a factor when you have spark.

Stuff happens and the computer could be history, but seeing as this started with a head change, something during the change seems most likely. One of the car places (O'Reilly?) claims to check ECMs, it's a last resort.

I read that you installed a new CPS do you have the old one still. Perhaps a corroded or dirty connector? :scratch:
 






I appreciate all the help and advice. Here's the latest in this fiasco- Checked fuel pressure; that's good at the rail. Disconnected and reconnected after 10 minutes; no change. I checked the coil with an extra plug wire and plug held to the block; no fire when cranking. So I checked the hot wire to the coil. No power to it. Checked the hot wire to the ignition module. Got power there. Changed module to one I know is good off my 1994. Still nothing. Jumpered the hot from the module feed to the coil hot wire where it also goes to the condensor. Still no fire at the plugs when cranking. Next step, I suppose, is to check for power going down to the new crank position sensor. What should I check for on the coolant temp sending unit?


CAPTIAN10 on May 27, 2015
I HAVE AN 1991 4 WHEEL DRIVE EDDIE BAUER, AT FIRST I THOUGHT IT WAS MY FUEL PUMP, YES I REPLACED IT AND DIDN'T HAVE TO, ALL FUSES AND RELAYS WERE GOOD, SO I THOUGHT IT WAS MY IGNITION SWITCH, NOT SO MY HOME BOY IS A DEISEL MACH.HE TRACED IT TO A SMALL SQUARE PLASTIC BOX DIRECTLY UNDER THE ASTRAY, WHEN YOU REACH UNDER THERE YOU'LL FEEL IT, IT'S SQUARE ATTACHED TO A METAL BRACKET, IT IS HAS A CONNECTER COMING FROM THE IMPACT SHUT OFF SWITCH, WHICH IS ON THE PASSENGER SIDE FACING THE ENGINE FIRE WALL, IT DID NOT ALLOW POWER TO GO TO THE FUEL PUMP, SO IT'S THE THAT SMALL PIECE OF **** SQUARE BOX, IN MY CASE, IT WOULD CRANK BUT WOULDN'T TURN OVER, I WOULD SPRAY QUICK START IN THE THROTTLE IT WOULD START AND STAY STARTED TILL I TURNED THE KEY OFF, THEN IT WOULD NOT START AGAIN, SO I MEASURED 7 INCHES FROM THE DRIVER SIDE PASSENGER WALL THEN 7 INCHES BACK TOWARD THE HUMP BEHIND THE SEAT AND I CUT A 7BY7 INCH SQUARE TO GET TO THE FUEL PUMP, THAT I DIDN'T HAVE TO REPLACE, JUST THAT SQUARE BOX FIXED THE PROBLEM ITS PROBABLY A RELAY IN THAT BOX I HOPE I HELPED TODAY I FOUND ANOTHER PART NUMBER ON THE UNIT E9EB-10D840-AA ITS CALLED THE DOOR CHIME CONTROL MODULE, ITS TIED IN WITH THE EMERGENCY GAS SHUT OFF THAT I EXPLAINED EARLIER ITS DRIVING FINE NOW OOMK
 






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