4.3 LX Engine stalls upon acceleration in FWD only

[CHIEF915]

My Starboard engine stalls upon acceleration in FWD only, you can shift into forward and it will slowly go at idle speed, if you up the throttle it stalls. History, put boat in the water, wouldn't idle properly, took both carbs off and had them rebuilt. Put Carbs on went on test ride, starboard engine locked up. Took plugs out and the water came out #2 cylinder. Replaced Exhaust manifolds and risers went out for another test run, engine would stall after being in FWD when you hit the throttle (gradually or slamming it down), the engine will run in FWD at an idle. The engine will rev up to max RPM in Nuetral and when in Reverse has all the power in the world. Replaced Coil, Distribitor cap, rotor, wires and plugs. Swapped Carbs between engines, the problem did not follow to the Port Side. Shut off the Starboard tank and only ran off the Port tank, no change. Took the fuel lines off and they are clear and undamaged. Replaced the filter in the mechanical fuel pump. Took fuel line off at Carburator and had someone crank engine, filled a gatorade bottle up in no time.

I just ordered a ignition sensor assembly that goes under the rotor, when I took it out it was rusty and pitted. Any other thoughts as I am running out. I don't think it could be the shift interupt switch as it shifts fine without stalling.

Engine serial # OC878104

Thanks for any input.

 

[Bondo]

My Starboard engine stalls upon acceleration in FWD only, you can shift into forward and it will slowly go at idle speed, if you up the throttle it stalls. History, put boat in the water, wouldn't idle properly, took both carbs off and had them rebuilt. Put Carbs on went on test ride, starboard engine locked up. Took plugs out and the water came out #2 cylinder. Replaced Exhaust manifolds and risers went out for another test run, engine would stall after being in FWD when you hit the throttle (gradually or slamming it down), the engine will run in FWD at an idle. The engine will rev up to max RPM in Nuetral and when in Reverse has all the power in the world. Replaced Coil, Distribitor cap, rotor, wires and plugs. Swapped Carbs between engines, the problem did not follow to the Port Side. Shut off the Starboard tank and only ran off the Port tank, no change. Took the fuel lines off and they are clear and undamaged. Replaced the filter in the mechanical fuel pump. Took fuel line off at Carburator and had someone crank engine, filled a gatorade bottle up in no time.

I just ordered a ignition sensor assembly that goes under the rotor, when I took it out it was rusty and pitted. Any other thoughts as I am running out. I don't think it could be the shift interupt switch as it shifts fine without stalling.

Engine serial # OC878104

Thanks for any input.

Ayuh,..... The lower shift cable draggin', causin' the interrupt switch to work, was My 1st thought, readin' yer story,.....

Have somebody Watch the switch, an easy test,....
If it actuates,....
Change out the lower shift cable,....

 

[achris]

My Starboard engine stalls upon acceleration in FWD only, you can shift into forward and it will slowly go at idle speed, if you up the throttle it stalls. History, put boat in the water, wouldn't idle properly, took both carbs off and had them rebuilt. Put Carbs on went on test ride, starboard engine locked up. Took plugs out and the water came out #2 cylinder. Replaced Exhaust manifolds and risers went out for another test run, engine would stall after being in FWD when you hit the throttle (gradually or slamming it down), the engine will run in FWD at an idle. The engine will rev up to max RPM in Neutral and when in Reverse has all the power in the world. Replaced Coil, Distribitor cap, rotor, wires and plugs. Swapped Carbs between engines, the problem did not follow to the Port Side. Shut off the Starboard tank and only ran off the Port tank, no change. Took the fuel lines off and they are clear and undamaged. Replaced the filter in the mechanical fuel pump. Took fuel line off at Carburator and had someone crank engine, filled a gatorade bottle up in no time.

I just ordered a ignition sensor assembly that goes under the rotor, when I took it out it was rusty and pitted. Any other thoughts as I am running out. I don't think it could be the shift interupt switch as it shifts fine without stalling.

Engine serial # OC878104

Thanks for any input.

There's the give-away statement... That confirms you are not looking for an engine problem per-sa... I think Bondo has it right, have someone watch the shift interrupt switch. Or, for the pruposes of testing, if you are on your own, disconnect it. Just make sure you understand the ramifications of that, and do it in an open area, with no other boats around. When you need to come out of gear, just kill the engine, slip it out of gear and then flash it up again.

 

[CHIEF915]

I pick up the ignition sensor assembly so I can reassemble the distribitor and then I will perform the test on the switch. I replaced that one two years ago with the shift cables, no problems until this spring, maybe it got bent or stepped on while performing other maintenance. I will follow up with my results.

 

[CHIEF915]

All, I replaced the ignition sensor assembly, it did idle better afterwards, but still stalled once in Forward. I adjusted the barrel on the shift cable a few turns and it was like magic, it worked like a charm. Thanks for pointing out the the microswitch, I was under the impression it would only kick on/off while going into and out of nuetral. I was wrong.

Got a new problem now, will post in a new thread though. Thanks again for your help Bondo and achirs.

 

[Bondo]

All, I replaced the ignition sensor assembly, it did idle better afterwards, but still stalled once in Forward. I adjusted the barrel on the shift cable a few turns and it was like magic, it worked like a charm. Thanks for pointing out the the microswitch, I was under the impression it would only kick on/off while going into and out of nuetral. I was wrong.

Got a new problem now, will post in a new thread though. Thanks again for your help Bondo and achirs.

Ayuh,.... That's Only supposed to work comin' Out of gear, 'n Only in the water,....

Yer lower shift cable needs replacin', or will soon,....