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4.9 distributor questions??? I need advice or suggestions.

977 Views 7 Replies 5 Participants Last post by  quins90lac
Well guys, I just did the top end on my '90 Fleetwood's '92 4.9 with the 7 pin large ICM. The car had been sitting since last May with a burnt valve. Hence the Valve Job. Anyway, initially after the repairs were done the car ran very well. It quickly degraded to totally awful. Rough idle, rich, wet plugs. FPR is ok, injectors new and not leaking down. Holds 41 PSI (ignition on, not running pressure.) New AC Delco OEM replacement plugs, wires, Accel Cap rotor and coil. I'm thinking the ignition module has failed. They seem to do that after sitting unused and being put back in service. Is there any way to check the module except by default? I have 798 ohms at 69 degrees resistance in the pickup coil. That is right at the edge of spec. One other issue is that the plastic around the ignition module wire female connectors on the 2-pin side is all broken and not able to be used. The 5-pin side is marginal. So my questions are:

1) Is the missing plastic going to cause any problem?
2) Is the pickup usable?
3) Any way to prove a bad ICM?
4) Does anybody have experience with the Mallory Hyfire ICM? Do they even make one for this application?
5) Would you just buy a new distributor? By the time I buy a pickup and a module...

I was expecting to upgrade the ignition anyway so this isn't a surprise. Oh, one more thing, I did get a distributor fault code before it went South; but since I cleared them it hasn't shown back up. The only current code is for the Cruise Control servo.
Thanks in advance for any advice.
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I've never had an ignition module sorta fail; they usually die altogether in my experience. I'll bet by the time you buy a pick up coil and module you would be getting close to the price of a rebuilt distributor. Did you ever check for codes? A vacuum test would be helpful to see if the engine is working properly and the valves are sealing properly.
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