Help? "Limp Home" mode kicking in for no reason... Not sure where to start?

[ally505]

I’d certainly be looking to rule out electrical problems and unwanted voltage drops.. My old MC had a main engine breaker that was corroded causing a significant voltage drop which subsequently played haywire with the ECM and gauges. Can you meter the voltage at the ecm, engine relays etc? You should be getting around 14v, anything less points towards a drop due to high resistance/corrosion somewhere or weak alternator as you have mentioned.

Are your LP and HP fuel pumps good, can you meter them when engine starts to misbehave?

intermittent problems are such a hassle, you have my sympathy, but remember there is a wealth or knowledge on this site to help solve the problem..

[MTRBTR]

Do you have perfect pass? I know that can do funny things sometimes.

[SoldTheBayliner]

Thanks guys... no perfect pass. “Correct Craft Cruise” which I never use... but it does work. Sounds like I need to get a hold of some good testing equipment...

[SoldTheBayliner]

Here’s one more clue, maybe... on the way out of the lake I spotted a friend in their boat, so I buzzed over in my boat to chat... sat there with it idling for a good 5 or 6 minutes, and then when I went to take off, it was missing from the get-go....
I have associated it with being under load this whole time... it always happens when I’m lugging it down, not up on a plane, with it “under load”... but this was clearly just the result of low RPMs for an extended period of time. This makes me lean toward an electrical issue where something isn’t getting the charge it needs under lower RPMs... like it has enough juice for a while, but then needs the higher RPMs to keep happy... what does that point to? Alternator? Or...? It has dual batteries and they are both good... I think...

[Peter6000]

Here�s one more clue, maybe... on the way out of the lake I spotted a friend in their boat, so I buzzed over in my boat to chat... sat there with it idling for a good 5 or 6 minutes, and then when I went to take off, it was missing from the get-go....
I have associated it with being under load this whole time... it always happens when I�m lugging it down, not up on a plane, with it �under load�... but this was clearly just the result of low RPMs for an extended period of time. This makes me lean toward an electrical issue where something isn�t getting the charge it needs under lower RPMs... like it has enough juice for a while, but then needs the higher RPMs to keep happy... what does that point to? Alternator? Or...? It has dual batteries and they are both good... I think...

I always believed in a more methodically way of troubleshooting instead of replacing parts.
Get some testequipment the key here is to at least find out if it's fuel or ignition related.
A oscilloscope would be the best to check the ignition but that can be pricy.
The simple tester I posted earlier may does the job.
At least get a voltmeter and check voltage on all the components ign.Coil, ecu, fuel pumps.
I don't think it's the alternator even if it stops charging the batteries should cover for quite some time.
And get a fuel pressure tester.
I looked around but ran out of time i could not find a service manual for the boat engine. Try to find out what car uses the same engine and find a diagram.
Post it and I can help you to check all sensors.
Peter

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[SoldTheBayliner]

Hi guys, me again....
A little update here...
The plan was to de-winterize and get it straight to the shop for some real testing on this issue (which is still unsolved... suggestions still welcome...) I'm an hour and a half away from a "real" boat shop/dealer so I was holding off on biting the bullet and dumping more money into this problem (I think I topped $500 last year trying to chase it down and never figured it out...)
So I de-winterized and took it out for the first time last week. For the record, the ONLY thing I did different from how I was running it last year was I put the batteries back in the opposite positions (last summer's battery 1 is now battery 2...battery 2 is now in the battery 1 spot). So we took it out and tried and tried to make it do the same thing, just to verify again what was happening for the shop... couldn't get it to do it. It ran absolutely perfect.

Took it out again today with the fam and again tried to run it at lower RPMs for extended periods.... let it idle for a long time... all the stuff that was causing it to cut out/misfire last year, and couldn't get it to do it.

So.... the mice fixed it over the winter, or....???

I'm completely stumped and now I'm frustrated that it's running perfect!! Haha! Never felt that way before!

Could a weak battery cause this?
I didn't even charge the batteries up before putting them back in and taking it out. I usually put them on at least a trickle charger over the winter.. didn't do that. They sat in the basement all winter and got put back in without being charged. I just swapped where I put them. When I run the boat I'm putting the battery switch on "all" not on 1 or 2. I always run it this way.

As I type this I guess I could try just running it on battery 1 and seeing if it cuts out, and just on battery 2...haven't tried that because I never really considered the batteries as a potential problem.

So now I don't want to take it to a shop to try to explain what's happening when it's not actually happening.... We'll see what the summer holds....

[Canuck-Surfer]

Hi guys, me again....
A little update here...
The plan was to de-winterize and get it straight to the shop for some real testing on this issue (which is still unsolved... suggestions still welcome...) I'm an hour and a half away from a "real" boat shop/dealer so I was holding off on biting the bullet and dumping more money into this problem (I think I topped $500 last year trying to chase it down and never figured it out...)
So I de-winterized and took it out for the first time last week. For the record, the ONLY thing I did different from how I was running it last year was I put the batteries back in the opposite positions (last summer's battery 1 is now battery 2...battery 2 is now in the battery 1 spot). So we took it out and tried and tried to make it do the same thing, just to verify again what was happening for the shop... couldn't get it to do it. It ran absolutely perfect.

Took it out again today with the fam and again tried to run it at lower RPMs for extended periods.... let it idle for a long time... all the stuff that was causing it to cut out/misfire last year, and couldn't get it to do it.

So.... the mice fixed it over the winter, or....???

I'm completely stumped and now I'm frustrated that it's running perfect!! Haha! Never felt that way before!

Could a weak battery cause this?
I didn't even charge the batteries up before putting them back in and taking it out. I usually put them on at least a trickle charger over the winter.. didn't do that. They sat in the basement all winter and got put back in without being charged. I just swapped where I put them. When I run the boat I'm putting the battery switch on "all" not on 1 or 2. I always run it this way.

As I type this I guess I could try just running it on battery 1 and seeing if it cuts out, and just on battery 2...haven't tried that because I never really considered the batteries as a potential problem.

So now I don't want to take it to a shop to try to explain what's happening when it's not actually happening.... We'll see what the summer holds....

Got an update? Did it run smooth all summer? Did you ever switch the batteries to see if you could re-create the problem?


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