1981 BlackMax idles, bogging w/throttle

[notfishing]

1981 BlackMax bog's down when I give it throttle. I've replaced the bulb, feul pump, filter, spark plugs. Ran fine with muffs on, out of water. Dump it into the lake last night and wont get any power when I give it throttle. It was running fine, cruising at 40 MPH and instantly started choking, etc.

 

[Joe_the_boatman]

Re: 1981 BlackMax idles, bogging w/throttle

Make sure the fuel tank vent is open (sounds dumb, but we forget the small stuff sometimes).

Make sure it's a fuel problem - when it's bogging down, squirt gas into the engine's air intake (have someone else at the helm). If it cuts off - it's too rich (unlikely) or there's an ignition problem. If it revs up, that means it was being starved for gas.

I'd guess it's being starved for gas. Since you've replaced the normal culprits (fuel pump/bulb), it could be that something got stuck in a a high speed jet (dirty carbs), water in the carbs, etc.

 

[Joe_the_boatman]

Re: 1981 BlackMax idles, bogging w/throttle

Another idea - try to mimic the problem with the engine in a big (50 gal) bucket filled with water. This puts back pressure on the exhaust, and you can safely (within measure) rev the engine. Revving the engine with just muffs on could turn bad real quick, since there is no load on the engine. You can also put it in gear.

Testing it this way, if you can get the problem to surface again, will save you a few trips to the lake for testing.

 

[notfishing]

Re: 1981 BlackMax idles, bogging w/throttle

Thanks for the tips! Do you think it could have something to do with the stator needing replacing?

 

[jnorswor]

Re: 1981 BlackMax idles, bogging w/throttle

mine was doing the same thing, finally put in some injector cleaner (per marine mechanics instructions) at the recommended rate and it slowly but surely got better. runs beautifully now.

 

[j_martin]

Re: 1981 BlackMax idles, bogging w/throttle

Not,
This is the second thread on the same problem. If you want to throw expensive parts at it, go right ahead. If you want to diagnose the problem first, ask questions, and listen to the answers.

my 02
John

 

[Joe_the_boatman]

Re: 1981 BlackMax idles, bogging w/throttle

Not,
This is the second thread on the same problem. If you want to throw expensive parts at it, go right ahead. If you want to diagnose the problem first, ask questions, and listen to the answers.

my 02
John

I second that. Stators pretty pricey and are fairly easy to test - nothing needed but a multitester and a screwdriver to disconnect it from the switchbox. Make sure it's bad first before buying one. Do a search (here) on your model to find out what resistances you should get when testing.

To answer your question, yes, it could be the stator (high speed windings). The fuel squirt test I described above may be a good start, or at least test the stator windings with a meter.

 

[notfishing]

Re: 1981 BlackMax idles, bogging w/throttle

J&J thanks. I'm all for not purchasing something I don't need to. You do get that the boat starts up great, and idles great, right? Just making sure. I'm not too great with all the parts and pieces and believe me, I'm listening to everything!!!! I'll try and figure out how to do these tests suggested.

JOhn - as far as the second thread goes, like I said, I'm new at figuring out this whole forum thing!