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350 V8 Marine Engine

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Old August 6th, 2018, 2:58 PM
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I'm hoping to get some ideas in troubleshooting my 2002 Inboard 350 Chevy. It's mounted in my ski boat and I've sort of run out of ideas on the issue.

The issue: Until this year, it's been bulletproof, pulling hundreds of skier's through our slalom course. Currently 880 hours and uses no oil and has always run perfect.

When starting up for the first time this spring, it was running rough and I realized I had swapped plug wires on cylinders 2,4, after putting in new plugs last fall.

It ran fine after that little escapade until about a month ago, when I was very low on fuel but idled out onto the lake to meet some friend's. I thought I ran out of fuel and got towed in. Filled the tank the next day and it cranks but didn't start.

Did some troubleshooting and swapped the two relay's (fuel and ignition) and it fired right up. So I installed new relay's, thinking it was, problem solved. Took the boat out and it started missing and cutting out at speed.

Since then, I've traced it to the distributor component's. This engine has throttle body F.I. and the distributor has a pickup coil, and the ignition control module.

The pickup coil measured over 6meg ohms but did generate about 1.7vac when rotated. I replaced the coil and measured the correct 800 ohms, generating .7vac when rotated.

Since that time, I can replace the ignition control module and it will start right up, but within a few moments start to run rough and eventually stall, always going back to a crank, no spark condition.

I've tested about everything else I can think of:
  • gray tach wire to coil, not shorted to ground
  • disconnect gray tach wire, still won't start
  • measure for DC volts at the coil. 12.8vdc and is consistent when it won't generate spark
  • test coil for primary and secondary windings, good
  • Remove Engine Control Module and send to reputable marine ECM supplier. All tests good
  • Test all sensor's (throttle body, IAC, MAP, knock sensor) each wire to ECM. No issues
  • New distributor cap and rotor
  • Plug wires are newer and ohm out consistently. Coil to distributor wire measures 890 ohms
I'm at a loss on what to try next other than replacing the complete distributor, assuming maybe that the magnetic components are intermittent.

Any ideas would be appreciated. The attachment shows what's inside the distributor.

RickR90s
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Old August 6th, 2018, 3:01 PM
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If it runs great intermittently, or after sitting awhile I'd say drain, clean the fuel tank.
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Old August 6th, 2018, 8:53 PM
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I am a fellow slalom skier and course addict; you mentioned 2002; what brand boat? I am a Malibu Crew member and your description sounds like a lot of failing fuel pump threads I have read since you have changed most of the electrical components.
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Old August 7th, 2018, 7:48 AM
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Originally Posted by Rednucleus View Post
I am a fellow slalom skier and course addict; you mentioned 2002; what brand boat? I am a Malibu Crew member and your description sounds like a lot of failing fuel pump threads I have read since you have changed most of the electrical components.
Its a MB Sports 190. PCM 5.7L HO. I appreciate the feedback but I replaced both low and high pressure (FCC) pumps last year. I verified a consistent 30psi when cranking or when it does run. I'm pretty sure it's ignition related as the injectors on the throttle body will spray, but only when there's spark.

I did fill it up with fresh fuel last weekend.

Thanks,

RickR90s


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Old August 7th, 2018, 6:56 PM
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Have you tried the MB forum?
MB Boat Owners Forum
If it's half as good as the Malibu Crew Club they will find your problem.
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Old August 8th, 2018, 8:40 AM
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Originally Posted by Rednucleus View Post
Have you tried the MB forum?
MB Boat Owners Forum
If it's half as good as the Malibu Crew Club they will find your problem.
I did. No replies so far.

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Old August 8th, 2018, 10:01 AM
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Try joining themalibucrew.com - they are a great group of folks and are happy to help "non-Bu" owners with their boats. Tell them Red sent you!
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Old August 8th, 2018, 4:24 PM
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More random thoughts --
Changed fuel filter yet? You mention problems started after running low on fuel; but that would not account for no spark condition you report.
Do you hear the fuel pump energize when key turned on prior to start?
Don't know if '02 is too new for this but an oil pressure switch failure will keep you from starting - if I remember it cuts power to the fuel pump, not spark.
You changed distributor ICM, might be worth doing that once again; new parts have been known to be bad
BTW I want to see more boat pics - MB's are sweet!
Going skiing tonight - will pick my crew's brains over beers for you.
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Old August 10th, 2018, 8:47 PM
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change fuel filter?
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