Igniton Problems or More?

[JRock]

I'm only running on one cylinder... '96 Challenger 787.

The recent background here is - found magneto and stator were destroyed from a mag bolt that had worked loose. I replaced both pieces with good condition used parts and reassembled. Carbs were just rebuilt (except for jets and needles), new fuel line, new oil lines, new gaskets all around.

She will start and run but only PTO side cylinder is firing. Compression is good on both (approx 160) and I replaced the ignition coil with a brand new piece from babbitts just for shizzies. I have spark on both sides but it seems to be somewhat weak.

When I start it and idle (it will idle with some help) for a couple minutes, the front mag side cylinder will fill up partially with fuel and the spark plug will be soaked.

I'm wondering if the mag side carb is possibly flooding the cylinder... Or if the weak spark is to blame... I'm having suspicions of a bad mpem or cdi. The charging system fuse was blown when I first discovered the magneto and stator problem. Otherwise the electrical box is clean and tidy.

Could the loose bolt that got jammed between the stator and magneto possibly shorted the system and fried either the cdi or the mpem???

Anyone been through this?

[dsolie]

Re: Igniton Problems or More?

yes, the bolt could have fried the entire system, but that would usually cause complete no spark, not weak.

When you rebuilt the carbs, what are they set to, I assume you replaced the spring for the N&S though, and if so, which one did you use? Did you verify pop-off and pressure test the carb after rebuild?

Are you positive you got a stator and mag cup from a 787 carbd and not a 951 or RFI? Did you install the Mag cup correctly using the same alignment marks you should have made off of your old cup?

[JRock]

Re: Igniton Problems or More?

The carbs were rebuilt with the kits from sbt with the internal gaskets, diaphragms, o-rings and check valves. I had a local boat repair business clean and rebuild them with the kits I provided. They handed them back when they were complete and I reinstalled them on my motor. The carb adjustments were not moved from their original setting. I'm not sure if they performed a pressure test or not.

I am sure that the magneto and stator are for a 787. They were identical to the pieces I removed and did not vary in any way.

The magneto cup was installed in the correct position, I could see the imprint of the old one on the flywheel and I lined up the new one to match.... Although I will probably end up pulling the housing cover one more time and verifying this so that I can be absolutely sure... after all, I was hanging upside down with my head in the bilge for over an hour.

So is this sounding more like a carburetor issue rather than an ignition problem?

[dsolie]

Re: Igniton Problems or More?

I would be looking at the carbs... It seems to me that the shop didn't set pop-off correctly, or at least didn't pressure test that carbs. The shop needs to make sure that the needle arm is flush or just a hair below the carbs body and that the diaphragm nipple isn't holding the needle open. Also, they need to verify they put the right gram spring in (the kits comes with many different spring options, only one will work for your pop-off.)

[JRock]

Re: Igniton Problems or More?

Well, sure enough it was the carbs. Got some solid help from a good friend who really knows his shiz.

The jets were clogged with junk and the needles were out of adjustment.

She started right up and is idling pretty well. I just gotta do a fine tuning and take her for a test run.

Thanks D for your input.

[dsolie]

Re: Igniton Problems or More?

Go back to that shop and get your $$ back! They charged you for a rebuild when they did.... what??

[JRock]

Re: Igniton Problems or More?

Well you get what you pay for.. Lesson learned again.

Took her out last weekend and she's running pretty good!!