After filling up with 87 octane it won’t stay running

[HFarr]

Maybe a vacuum leak somewhere

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[Holdmybeer]

You can find vacuum leaks with wd-40. Spray and if the fluid gets sucked in it runs better for a second. Worth a shot.

Timing could easily be the problem. Bolt on distributor could have vibrated loose and twisted some. I believe 5* advanced on older 5.7 GM motors.

[Mondo14]

So after over a month at the local dealer they finally found the issue. It's a bad harness to the injectors causing 4 injectors to not fire. So after changing the cap and rotor, changing the plugs, draining all the fuel, testing the injectors, changing the crankshaft sensor and throttle position sensor, finding no vacuum leaks, they had to order this fuel injector test kit. They said the signal is getting sent out of the ECM but not making it to the injector as this test kit had lights on the injector side of the harness and they could tell the wiring is bad because they weren't lighting up. They said I could try and check the harness for damage and fix it but that they could only replace the entire harness. So I'm going to attempt to troubleshoot this harness and probably end up ordering one and replacing it myself over the winter. If anyone knows a good place to buy the engine harness let me know.

[sandm]

indmar. I'd call them and ask. sure skiers choice or your dealer can source the part but I'd go straight to indmar.

[Mondo14]

Well I finally figured it out and got it running. It was the ECM. Tested the harness with the pin out from Indmar and it was good so ordered an new ECM from inboardonline.com and they had it to me in a few days. Put it all back together with the new ECM and it started right up! So relieved to finally have a working boat but now to wait till spring to get it in the water.

[HFarr]

Maybe it will keep working till then! LOL! When I was in high school, I had a 1972 Dixie Craft with a 105 Chrysler on it. My friends and I would put the water muffs on the foot and fire it up at the house to make sure all was good. We would load up, get to the lake, and 90% of the time it wouldn't start. Take off the cover while floating next to dock and start re-checking everything! Would clean the points, check for fowled plugs, fuel, spark, everything until it would crank. Drove me absolutely crazy as it did that so often. Once it decided to crank at the lake, it was good all day though. We were determined that we drove through some mysterious Burmuda Triangle zone on the way to the lake that just scrambled everything! Or the boat was like Christine and just did it to mess with us!! Hopefully your boat likes you and will crank again as it should when you put it back in the water!

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