91 740 non turbo still won't start

nisan17 · Post by **nisan17** » 13 Sep 2012, 13:54

Okay, About 10 days ago it started and ran for a day. Then it just won't start again. No spark. When it cranks it has fast cranks and slow cranks, seems like it wants to just take off at times. I changed out the ignition module, in the inner fender. Still no spark. Should I replace the CPS? Is there a way to test that?
Any other ideas will be greatly appreciated?

Thanks Much,

russellengineering · Post by **russellengineering** » 16 Sep 2012, 21:38

Hi Kevin,

The CPS is a good thought. The FAQs have guidance on testing it and you can give it a whirl. However, I would find and clean it where it enters the tranny bellhousing and see if the insulation is cracked or gone. It it is, pull and replace. I just did this in the Spring to my 93 940. The wires were exposed at the bellhousing and it cracked at the other plug end when I pulled it. They just get hot and go bad after 20 years. FYI, I never could get a code when it went bad, but when I replaced it all my no-starts and stalls went away. I was really hoping to get a code just to say I had used the OBD successfully for once. Have you gotten any codes from the OBD?

Otherwise, you did not say if you had Regina or something else for the ignition. If you replaced your Regina power stage with a new one it should be good to go. However, a used one from another car needs to be cleaned if it never has before. I am not so sure about non-Regina ignitions, but I imagine it is the same issues. Is the power lead from the ignition module to the distributor good?

Those are my thoughts. Good luck!

Dave

nisan17 · Post by **nisan17** » 16 Sep 2012, 23:38

Dave, no OBD codes. Ordered new CPS and praying it will do it. I have faith it will.

Thanks again,

Post by **chrism** » 25 Sep 2012, 20:39

Peak into the oil filler port while an assistant cranks the engine to make sure the cam is turning.

Post by **billofdurham** » 26 Sep 2012, 11:50

Kevin,

A little late as you have ordered a new CPS but this is how to test it:

740 CPS check.pdf: (104.65 KiB) Downloaded 136 times

The check is listed for the '91 - '92 cars so you can work out which reading relates to yours.

Bill.

nisan17 · Post by **nisan17** » 28 Sep 2012, 18:45

Bill, I put on new cap and rotor. No start. I'm out of ideas. I've tested my coil..good. Do i just put on a new take off on it? Test coil again? One time a couple weeks back it started and ran a day??/?/?/??

Thanks,

kevin

Post by **rgk** » 02 Oct 2012, 21:26

Check all your wiring, terminals, connections, everything. Check, double-check, triple-check. A bad ground might give you a spark sometimes, yet prevent you from getting that spark most of the time, which would explain why the car might start every once in a while.

Check the engine to body ground strap. Check the battery cables. Remove the wiring at each connection and very carefully, in good light, check under (inside) the crimped terminal to see whether you have any corrosion. Scrub every ground connection with a wire brush.

I know there is a troubleshooting procedure to determine why you might not be getting spark in the Haynes 240 manual, but I can't seem to find something similar in the 740 manual. The 240 manual says this: for breakerless and computerized ignition systems, if there is no spark, disconnect the 3-pole connector from the distributor. Install a calibrated ignition tester into one of the spark plug wires. Turn the ignition switch ON (engine not running) and jump terminals B and C and observe a spark at the plug. ... If there is no spark at the test plug and there is battery voltage present at the coil, check for battery voltage on the blue wire directly at the ignition module electrical connector. If there is battery voltage present, check the ground strap for continuity or damage.