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1988 2455 bayliner 57L OMC Cobra Cutting out to Idle

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yukoner

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My 1987 5.7 OMC Cobra starts a

My 1987 5.7 OMC Cobra starts and idles perfectly.When I am pushing down on the throttle to gain rpm/speed the motor will at different rpm's and speed just cut out back to the idle speed.It does not overheat/shake/sputter.I changed the filters. I move the throttle back to neutral and it is idling well. Throttle forward cuts out again..anyone know what is wrong? Thanks! }
 
"Ayuh,... Sounds like a Carb i

"Ayuh,... Sounds like a Carb issue....

Maybe it's time to Rebuild it with a Carb Kit..."
 
"The motor runs absoutely smoo

"The motor runs absoutely smooth after quickly starting. It will idel all day without a hiccup. Have you ever heard of this before? What would rebuilding the carb do to it to correct this? Also, someone mentioned the coil, and a switch that cuts out the motor if overheating, etc but I cannot find any switch to check to see if it is deffective. Do you know if the carb is a standard Chev 350 carb or are they different for marine motors? Thanks again. There are no boat repair shops within a few hundred miles of me."
 
"I'm not clear as far as w

"I'm not clear as far as what the symtoms are. It sounds like your saying the engine just suddenly goes back to a normal idle no matter what the throttle position. If so, that's something I've never heard of. Now if it's actually cutting out or bogging down under load I might have some suggestions.
Some questions:
Does this only happen when you first shift out of nuetral? Does it happen when reving up in nuetral? Please give all the detailed info you can."
 
"It only happens when I am und

"It only happens when I am under load, pushing the throttle forward. If I slowly/or quickly push the throttle down it will cut out at all different rpm's. Once and a while I can get the boat on step and then it will just cut out. By cutting out I mean the motor will just suddenly cut back to an idle (not stop or sputter) I can smell gas fumes sometimes when it does this. I move the throttle back the the neutral position and it will just idle perfectly. I checked the lickage of the throttle to the carb and it is all tight, changed the fuel/carb filters/cleaned the flame arrestor. Still cuts out. It did cut out on me for several hours the other day and then it just worked perectly for an hour. The next time I took it out it again it cut out at all different speeds/rpm's. I am in the Yukon and the closest shop is way off in Alaska so I am stuck trying to figure this one out...thanks to everyone for your time and consideration."
 
"Mark, Have you found a soluti

"Mark, Have you found a solution? I'm experiencing the same problem with a 4.3L 1986 OMC Cobra. A friend suggested replacing the waterpump in case the engine was overheating under load and causing the computer to shut it back to idle. I haven't had a chance to try this yet, but was curious if there was something you found helpful."
 
"Steven....you would be much b

"Steven....you would be much better off starting a new post for your problem rather than tagging onto an old thread, many people may not see your update. In reference to your friends idea about the over heat and the computer, 1986 does not have a computer but some of the newer ones did in the mid to later 90's. They did have a module that would go into SLOW mode if something was wrong which would limit the RPM's until fixed."
 
"I had simular problem, differ

"I had simular problem, different engine, turned out to be a wire from heat sensor was breaking down due to insulation was to close to a heat source and the sensor thougt the engine was over temp although no audiable alarm."
 
there's no computer on a 1

there's no computer on a 1986 or 1987 cobra.

really sounds like an ESA/linkage problem
like the ESA switch is right at the point of contact closing
 
Agree with Hy Stat the shift c

Agree with Hy Stat the shift cut out microswitch could be intermittent malfuncion or the ESA module starting to break down.
 
"Not so sure it could be the E

"Not so sure it could be the ESA, especially if it's the older style from that time period where it still has the overstroke switch wired in. If it's in either fwd or rev the overstroke is to prevent the ESA from accidently kicking in. Of course if it's been replaced with the newer style then I could be wrong. If in doubt just unplug the ESA and test the engine without it."
 
It turned out that the overstr

It turned out that the overstroke switch needed adjustment. I've been dying to try some things and was finally able to this past week. Thanks for the help all!
 
"Bob, you are awesome! I was

"Bob, you are awesome! I was relying on your expertise since there are no marine machanics up here and you were right. I simply unplugged the ESA and it} ran like a charm. This was the first weekend since the ice came off the water that I could try it out. Thanks again for making this possible for me. Take care,

Mark (Yukoner)"
 
"Mark....keep in mind that unp

"Mark....keep in mind that unplugging the ESA is a method of trying diagnose a cause, you shouldn't continue to run that way as it will be really hard to shift out of gear. Either the ESA is bad or it's being activated at the wrong time. You need to keep going and fix it."
 
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