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No start, weak spark 700 1988

Howdy,

Coil resistance was 11280 ohms, both sides were identical.

Please explain "both sides were identical". It sounds like you measured from the tower to - and from the tower to +, is that correct?

At the KΩ range you would not see any difference between those two readings. You need one more measurement, from + to - using the lowest Ω scale to verify the primary side.

But, I have had several coil failures through the years on different vehicles. I don't recall ever getting conclusive resistance checks (like an infinite reading) on any of the failed coils while the coil was cold. Without a measurement of the coil known good to compare to the measurement during troubleshooting, I would not put much stock in a resistance check.

It sounds like you have touched all the bases for spark except for the ignition amplifier (power stage) and the ICU. I doubt the ICU is at fault. If it does not issue pulses, the pumps don't run. It could be a problem but I think the power stage is more probable for weak spark.

Before replacing parts though, the orange spark during your check may have been because of a poor ground for the plug or a bad plug wire. Hold off on that until you investigate the pumps a little more. After all, noisy pumps is what brought you to this party, right?

...but what does that low current draw mean then?

Well, without a voltage reading taken at the pump, you just don't know what the low current draw indicates.

If the open circuit voltage is normal, the low current draw would mean the pump, or the ground point for the pump, has become resistive. If the open circuit voltage is lower than normal, the low current draw may be correct. Disconnect the pump and measure the voltage available to the pump.

The in-tank pump is grounded in the trunk. The main pump picks up ground at the ground rail on the relay board.

...I unplugged the prepump connector in the trunk and stuck my multimeter in there to check the amps on the fly. 2.15, and the car sputtered to a halt as it had already sucked a few too many air bubbles.

I believe you started with a dying main pump and a weak in-tank pump. Pulling the connector off the in-tank pump may have sent the main pump over the edge. But, until you get some voltage readings to go with your current readings, everything is just speculation.

Revisit the basic stuff first; power and grounds. Check voltage on both sides of the fuses involved. Verify no more than .5V drop across the ground points. Also check voltage on both sides of the fuel pump relay. Do you have schematics?

--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)






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New No start, weak spark [700][1988]
posted by  TXMatti  on Sun Mar 8 17:24 CST 2009 >


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