See if This Stumps You....

[TrapperJohn]

Background: '92 Seaswirl w/5.8L/351 Ford and OMC King Cobra sterndrive. (I know, I know...but somebody has to drive one.:redface:)

Here's my latest frustration. :bigshock:

Symptom:

Boat runs for 10-15 minutes @1000 rpm through no-wake zone. Within 5 minutes after hitting 2500 rpm, engine begins to run rough until rpms drop to 750 - then she stalls out. Temp gage says 120. Problem appears to be thermal because a 5 minute rest will allow a restart, but the next failure failure occurs more rapidly.

The starter will not turn over immediately after she stalls. After rest interval, ignition occurs normally. Alternator output checks out. Batteries check out. New coil, distributor, and ignition module this season.

Suspicions: water pump impeller, faulty shift interrupt switch and/or ESA, or both. I have noticed an occassional lag before reverse engages - but not always. Here's another weird thing - I have replaced the kill switch twice since May!:shrug:

[fishingls]

I would look at the fuel system. Do you have an in tank or in line filter? Check them, symptons sound similar to a filter concern or dirt, debris or something in the fuel system. If that all checks out, the next place to look is the carb. Sometimes a drop off in engine performance with stalling is caused by a build up of dirt somewhere in the fuel system and the clog loosens up allowing a resart with repitition of the problem.

[marys netter]

Once had a Wierd problem on a glasply with the fuel/water seperator and a little check valve in the intake side, almost made me and my wife a hood ornament on 4, 70 ton tide water barges:twocents:
The electrical problem wiyh starting may rule this out though!
GOOD LUCK:cheers:

[ballison]

Background: '92 Seaswirl w/5.8L/351 Ford and OMC King Cobra sterndrive. (I know, I know...but somebody has to drive one.:redface:)

Here's my latest frustration. :bigshock:

Symptom:

Boat runs for 10-15 minutes @1000 rpm through no-wake zone. Within 5 minutes after hitting 2500 rpm, engine begins to run rough until rpms drop to 750 - then she stalls out. Temp gage says 120. Problem appears to be thermal because a 5 minute rest will allow a restart, but the next failure failure occurs more rapidly.

The starter will not turn over immediately after she stalls. After rest interval, ignition occurs normally. Alternator output checks out. Batteries check out. New coil, distributor, and ignition module this season.

Suspicions: water pump impeller, faulty shift interrupt switch and/or ESA, or both. I have noticed an occassional lag before reverse engages - but not always. Here's another weird thing - I have replaced the kill switch twice since May!:shrug:


I have seen this a few times over the last thirty years its usually fuel related as the first response says to your post I will add a couple of things to check poor the fuel out of the fuel filter in to a glass jar look for water separation if thats all good remove the anti syphon valve from the tank and replace it they get dirt or debris easily then the check ball hangs up when vacuum is steady and releases when the vacuum is gone.

[chucks electric]

hello, check the fuses on the rear of the engine, omc uses fuses were merc uses circuit breakers. the fuses will get corrosion in them and loose power to the ignition switch, this might explain the no crank. one fuse is for helm power and the other is for trim motor.