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1988 omc 57

D

dhondarider

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just bought my boat. i was tol

just bought my boat. i was told it needed a carb adjustment cuz it would die at full throttle. started it in driveway and it idled and ran fine. took it out sunday and above 2000 rpms it will accelerate for a second and bog down. anyone know why ? it has a rochester 4mv on it. thanks
 
"The main jets controll the fu

"The main jets controll the fuel delivery. They would be my first "look". You can have delivery problems that behave the same way. If you have a remote tank you can hook up, it can seperate a lot of issues from your delevery system, and you can pump it's (the remote tank) primer bulb to check the fuel pump on the engine and the filter in the carb. (By over pressuring the filter).

Often minor contamination of the carb can be cleared by reving the engine to 1200 and slapping your hand over the intake. Keep it there till the engine quits. Then with some throttle to clear the excess fuel do a re-start.

Often this will either clear the obstruction or cause a change in the way it runs so you are sure the carb is at fault."
 
"if it was my boat first i wou

"if it was my boat first i would, clean the filter at the inlet fitting that enters the carb.

clean the filter in the fuel pump if so equipped.

dump the fuel water separator, into a clean container and see if there is water in the fuel.

i would check the pressure the fuel pump is giving between 4-7 psi no less.

Then run it on a external tank of fresh gas and see if that is your problem.

your problem not fixed? Then try what follows;

rebuild the carb, run it again on the external tank, problem fixed?

Not fixed? try what follows;

i don't remember, you have esa on that motor?

If yes disconnect run it again on the water, post the result, it is possible for a malfunctioning esa module to cause the symptoms you describe."
 
that would all work great for

that would all work great for me.... but it doesnt do it in the driveway... runs perfect w a hose to it??????
 
workin on it now... w the engi

workin on it now... w the engine running...and at full throttle.. the flaps on top of the carbs do not open. arent they supposed to? vacuum appears to hold them shut. the choke works perfect. and i get good fuel. the flap that the choke is attached to works fine. the larger flap to the rear of the carbs above the secondary flaps to the intake do not open. but it still runs perfect in the driveway.
 
i read an older post about a g

i read an older post about a guys 5.0 omc doing exactly the same thing. id love to have this work out so i can put it in and enjoy it sunday. it turns out it wasnt plugs or gas. he never posted his findings.
 
"your never supposed to go abo

"your never supposed to go above 1200 rpm in the drive on a garden hose will collapse your GARDEN HOSE CAUSE THE HOSE CANNOT DELIVER ENOUGH WATER TO THE DRIVE.

Just wanted to highlight it for you, and make it jump out at you that sentence.

where you located?"
 
fuel delievery is where I woul

fuel delievery is where I would look first. even if the four barrels are not opening up you should still be able to accelerate slowy to full throttle. you can unplug the ESA and go for a test drive to see if that is the problem. another possibility may be a restriction in the exhaust.if the shutters are stuck or have broken off they will block the exhaust passages and bog the engine down at higher rpms and throttle
 
im located in connecticut near

im located in connecticut near danbury. understand about the hose. had to see if it would do it or not though. im thinking its exhast related. like something blocking it. i dont have shutters on mine. so when in water the exhaust is below water level. i have no other explanation as to y it does it only in water.
 
how does your boat exhaust is

how does your boat exhaust is it a through hull exhaust or does exhaust through the drive
 
thru hull below swim platform.

thru hull below swim platform. i just ohmed out the esa switches. meter fine. its a 1988 four winns liberator 350 king cobra.
 
"Your easiest ignition tester

"Your easiest ignition tester is your timing light. Pick you simplest wire to hook the timing light to and tie the trigger of the light down so it fires all the time. Then take it for a ride and see if the ignition starts to drop out before during or after the event. If not you havent wasted a lot of time there.

That carb only opens the fron set of butterflys with the throttle, The secondaries are locked shut till the correct amount of vacuum is applied to them. "
 
"I have seen them "wired s

"I have seen them "wired shut" for economy. The engine vacuum runs thru an internal circuit and pulls them open only after the primaries have reached a certian spot. The inter lock for this is on the side of the carb and looks like a bunch of bent coat hangers. You might be able to find the release by watching the throttle advance and manually trying to open the secondaries. (Engine off)

Sorry bout the rather convoluted explaination, but I have always had the carb in front of me."
 
"If your running it WOT in the

"If your running it WOT in the driveway, no they won't open.. The motor needs to be loaded, at WOT on close to it, before they will kick open.
If you can see your engine from the controls, watch when your running across the lake.


P.S.
They all run great in the driveway. NO LOAD..."
 
"On those air valves on the Q-

"On those air valves on the Q-jet, the choke pull-off will keep the air valve closed until it 'bleeds out', usually 2-3 seconds. So a quick flick of the throttle will NOT be enough to cause them to open.

They will corrode shut given enough time in a bad environment. best to check with engine off, you should be ble to 'open' them by pressing down on the flat part of the air valves. If it won't open, find where it is binding and remove the cause."
 
i got the boat and trailer for

i got the boat and trailer for 300 bucks. its in excellent shape other than running at 2000 rpm. i had to rebuild the bench seat and that was it.
 
"The air valves will need prob

"The air valves will need probably 3 seconds at 3000 rpm, maybe up 3400, to open."
 
i guess ill just got thru the

i guess ill just got thru the electric aspect first.1. i think my bat is low. 2 i did not pull plugs to look at condition . ill let everyone know what i find out. thanks
 
"so i just went thru and chang

"so i just went thru and changed the fuel water sep. the carb filter(which was horrible by the way) and cleaned the flame arrestor. i had tested the esa switches and they ohmed out ok. but when i was running it in the driveway on sunday i hit the switch w my hand and it didnt slow the rpms. did it a couple times and then it started working properly. maybe it was stuck i dont know. but by doing these things it ran great. thanks for all the help. too bad i couldnt pin point exactly which one it was, maybe all of the above."
 
It was probably a combination

It was probably a combination of all. Glad you have some results!!! Sometimes I think all the great suggestions from every one here are wasted. Am sure every one here will agree-- Good Work Derek!!.
 
"it is my second boat. my firs

"it is my second boat. my first boat i only got to take out twice last season.. sold it and had enough money for a diesel truck and my 88 four winns. worked out i guess. these forums are great. quick ways to fig out atleast where to start, esp when you have no idea. im sure it woulda been hundreds at a dealer / marina. fixed it for 14 bucks."
 
"<font color=""ff6000"">"i

"<font color=""ff6000"">"i had tested the esa switches and they ohmed out ok. but when i was running it in the driveway on sunday i hit the switch w my hand and it didnt slow the rpms. did it a couple times and then it started working properly. maybe it was stuck i dont know. but by doing these things it ran great. thanks for all the help. too bad i couldnt pin point exactly which one it was, maybe all of the above."</font>

Like I said, they always run great in the driveway. Get it on the lake and make sure it's fixed."
 
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