RWD - Intermittent No Start happened again today after storm front rolled through

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Intermittent No Start happened again today after storm front rolled through 700 1991


Nothing definitive at this end, but I can at least address your observations as I interpret them.

"I have checked for spark and there is what looks to be intermittent spark (tester hooked to plug wire and grounded on engine, crank 4-5 times then one spark)."
• Sorry but I can't come up with a solid comment here, not knowing what kind of "tester" was used, for one thing. Was it a spare plug? Or the kind of tester with a variable gap? And if so, what was the gap set at? Was there a good, solid connection to a good ground?

"I pulled a spark plug and the hook part of the plug is dry but the center tip (main body of plug) is wet after several cranks. So I am pretty sure it is getting fuel"
• It may just be getting a sip of fuel from the pump "prime" cycle every time the key is turned to ON. However, if it's getting "normal" fuel pressure, then we can assume (yes, I know) that the Ignition system is basically working, because its timing pulses are allowing the FI system to run the pumps. Even so, there could be a problem with/at the ignition coil. It's held on to the heat sink with 2 torx head machine screws. Try cleaning it's contact posts and the mating spring terminals shown below.

"but I also tested the voltage at the injector wire and it seems as if there is 8-10 Volts on BOTH connection points of the injector wire???? Seems odd."
• Another tricky one here. Because except for the short time each injector is grounded, it will have 12v applied to its ground side from its parallel connection to the other 3 injectors and the solid 12V being applied to (and thru) them.

In other words, the common ground side of all 4 injectors is not a solid connection. It's controlled by the ECU 4 times per rev (once for each cylinder). What I don't know is the duration of those ECU ground pulses. Or how responsive your meter is. But my gut feel is that what you saw was normal. At least until Art rings in to explain it weller, as only he can;-)
[This would be a good time to have a 'noid light to test injector pulses.]
['noid is shortened from solenoid]

"one suggestion I've received is that the system supplying spark should be continuous therefore supplying a regular ongoing spark rather than an intermittent one."
• Just one spark "interval" per plug per revolution. Might seem continuous, if looking at the coil wire, depending on engine rpms.

REX Coil removed from Amplifier heatsink

REX Coil connections

Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.


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New Intermittent No Start happened again today after storm front rolled through [700][1991]
posted by  Strackerjack  on Tue Oct 26 13:04 CST 2010 >

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