1996 7.4 mpi efi still no spark
#11
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fixx
i forgot to mention that the motor turns over very good it has two batteries the main doesnt turn the motor very good but with the switch on both it turns over very good but still has 9 volts at the coil , and both batteries at rest with the switch on both have 11 volts , does it still hvae a possiblaty battery problem causing no spark
also undo the main plug that goes to the main engine electrical harness,,clead and pry open all the terminals,if one was loose and from it getting hot it melts the rubber then someetimes the terminals will touch or coat the terminal with rubber when it cools off..
Last edited by FIXX; 10-13-2012 at 02:25 PM.
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It's an efi engine, so the tach lead doesn't come from the neg. side of the coil. The ecm sends the tach signal. A bad tach will cause them to misfire on the top end but I haven't seen it cause them to not fire at all. Guess anything is possible though.
Eddie
Eddie
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whe the motor runs the tack works fine , the motor does have a little surge in it betwee 800 to 2000 rpms but it not to bad i put a volt meter on the batteries both at rest but still hooked up but the battery switch in the off position and they both read 11 volts
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if you have a strong battery (+13V) just take a wire from the + side of the battery and connect directly to a purple somewhere on the engine.
If it runs you have a wiring harness problem somewhere...
If it runs you have a wiring harness problem somewhere...
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Still No Spark 1996 7.4 mpi efi
ok guys i bought a new battery 1050 cca, use my battery charger to supply 12 volts to the purple wire in the harness that goes into the ecm and still no spark wont start i also isolated the other battery while i tryed to start the motor, i did notice that the motor sounded different when it truned over when i gave the purple wire 12 volts which was really like 15 volts , sounded like the motor had a different sound when turning over like it was zinning or wining kinda but when i took off the lead to the purple wire it quit sounding like that , i did fire once at first then nothng after that , check grounds, fuses , tryed to hot wire it at the key switch still nothing any more ideas guys , thanks james, oh and not corrsion in the 10 pin plug , the wiring harness is new like 4 years ago., the tack works fine when the motor started before