Indmar Bogging

[ranger098]

Boat did this a little bit last year, and this year seems to be worse. She will start and idle fine, and rev up to about 2500-3000 RPM, but cannot go past that, falls on its face. Its almost like when the PP is set and you try to go past that speed, but this happens even in neutral. The tach also jumps erradically when the engine starts stalling. Engine never dies, and when i let off throttle it still runs great.

Indmar 350 carb, 2002 Moomba Mobius LSV

replaced cap and rotor, and fuel pump and filter. I have oil pressure according to the guage, and water temp is good as well. Tired of throwing parts at it and guessing..... any help appreciated

[tex599]

Have you rebuilt the carb yet? Most likely the issue if you have replaced the cap, rotor, fuel pump.

[ranger098]

I havent done that yet, could this also make my tach jump around though? That's the main reason i havent messed with the carb.

[zabooda]

I tap on the bezel and it settles the tach down. I had similar issues and had the carb rebuilt to only find the electronic ignition was acting up and I replaced it.

[ranger098]

I tap on the bezel and it settles the tach down. I had similar issues and had the carb rebuilt to only find the electronic ignition was acting up and I replaced it.

what part of the electronic ignition? I am thinking of checking further into the distributor or ignition module...

[parrothd]

If you slowly add throttle does it go past the 3000rpms?

[ranger098]

If you slowly add throttle does it go past the 3000rpms?

Neither slow or fast will change the issue, also it's not strictly 3000 RPM, yesterday it started around 2000, and couldnt get to 3000.

P.S. i got half a mind to buy your boat from you again..... doubt the timing will work out though, but she looks great.

[parrothd]

Sold already.. Lol..

Try squirting some fuel into the intake when it's stumbling, if it runs better than it's fuel related.

You sure the choke is opening?

[ranger098]

Sold already.. Lol..

Try squirting some fuel into the intake when it's stumbling, if it runs better than it's fuel related.

You sure the choke is opening?

Yes two of the 4 barrels are open which as i understand is normal when revving in neutral (not under load). I havent looked when someone else is driving. Ill try some gas into the carb though, good suggestion to narrow the troubleshooting.

And congrats on that sale, and the new boat.

[parrothd]

No, the choke plate should be fully up/open and after a few minutes of running. The choke is the black flat piece that moves covering the 2 intake barrels. Lift it open when the engine is running and test, check the 2 wires connected to the choke, those can come off.

[ranger098]

UPDATE

seems to be a bad ignition control module, i took that off the distributor and there was a little corrosion on two prongs. cleaned that and reinstalled for testing and it ran perfect. getting a new one today and heading out for a lake test. tried all the other steps listed here (spray carb cleaner around the intake, checked power at both v drive pressure sensor and oil pressure sensor, checked power at ignition switch, etc) Thanks to all that responded.

[ranger098]

I need to revive this thread, the issue remains and ive learned a little more now.

After about 20 minutes of running, the issue will go away and not come back for the day. Another interesting thing happened the other day, i came to find both batteries dead and i dont think i left anything on (who knows tho). Gave it a jump, and ever since then the tach bounces around in addition to the boat not wanting to rev out. i think the tach bouncing could be an indicator of where the problem lies, somewhere in the distributor, but not really sure what to look at there.

Any thoughts? Troubleshooting is hard, because after enough tinkering the issue isnt even there anymore. so ill replace something and think its fixed, till next time i go out. So far replaced ignition control module, spark plugs, cap and rotor, fuel pump and fuel filter. could try plug wires but i couldnt find them locally and havent ordered them yet.

[parrothd]

I need to revive this thread, the issue remains and ive learned a little more now.

After about 20 minutes of running, the issue will go away and not come back for the day. Another interesting thing happened the other day, i came to find both batteries dead and i dont think i left anything on (who knows tho). Gave it a jump, and ever since then the tach bounces around in addition to the boat not wanting to rev out. i think the tach bouncing could be an indicator of where the problem lies, somewhere in the distributor, but not really sure what to look at there.

Any thoughts? Troubleshooting is hard, because after enough tinkering the issue isnt even there anymore. so ill replace something and think its fixed, till next time i go out. So far replaced ignition control module, spark plugs, cap and rotor, fuel pump and fuel filter. could try plug wires but i couldnt find them locally and havent ordered them yet.

Just had a similar issue on another boat, what's the voltage while running on the guage? I'd check the alternator wiring, you should be getting 13+ volts.

[ranger098]

Just had a similar issue on another boat, what's the voltage while running on the guage? I'd check the alternator wiring, you should be getting 13+ volts.

It varies with the RPMs, but it’s definitely not 13, I’m usually happy to see 12 volts, but it’s usually under 12. Power has always been low at the dash too

[ranger098]

So I did some more poking around today and found that at idle, the purple wire on the alternator is putting out about 11v. Main orange wire is a good 13.9-14. What’s the right voltage for that purple wire?