Tried several sugestions, need more please,1988 4.3 GM V6 OMC

[Donald Terrell]

I have a 1988 sunbird corsair which used to run great. The last four trips not great. First signs of trouble the boat would stumble when I first took off then it would barely get on plane running real bad but shooting forward like it used to run for only seconds at a time. I found my thermostat broken and replaced. I checked condition of wires, dist. cap,points, some plugs the easy ones to reach,checked water separator for water and found none. I performed a fuel pump volume test-okay. Took it out again and no go even worse. Then I rebuilt the carb, back to the lake and no go again. The boat idles and throttles up okay on the muffs. When in the water if it doesn't stall, you have to work the throttle so it doesn't stall, at WOT it's going 5 miles an hour bow up. I feel good about the carb rebuild. I looked into the carb as my wife worked the throttle and saw two streams of gas shoot out. I tried running with gas cap off. The shifter is hard to move into forward or move out of forward. I disconnected the shift cable at the lever on top of the engine and the shifter moved fine so I know there is a problem in the lower cable which is the recalled one red. Could there be such a problem in the outdrive hendering the engine from turning when in gear? Coil? I just don't know what to try next short of taking it to the shop. This boat once ran 40 mph smoothly. It seems to run good in the driveway but won't go in the water. I have a Cylmer manual. Please help someone?? Oh yeh, I tested the ESA switch, when in idle it worked and stumbled the engine but when in gear moving forward it didn't seem to make any change when depressed. I thought maybe the ESA was staying engaged so I carefully bent the arm so it wouldn't work but that didn't help either and I bent the arm back inplace.

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

One more thing I have noticed that there is always water in the bilge and I am sure it's not coming in over the edge. Last trip testing the boat 2 hours I let apr. 8 gallons run out. Sorry for the long sphill, just trying to provide as much info as possible, Thanks!!

 

[Chris1956]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Don, I think you should start to eliminate issues, to narrow it down a bit. I would pull the spark plugs and look them over. Replace if necessary. Take a compression test while they are out. Now start it up on the muffs. Run your hands over the plug wires to feel for arcs. Examine the dist. cap and rotor for cracks, carbon traces and dirt. Also watch for water dripping into the bilge from a manifold or block drain or a leaky hose. If it has been several years since you replaced dist. cap, rotor and wires, now may be the time. If these all check, suspect ignition module or carb.<br />I do not know much about OMC drives, but the bad shift cable shouldn't affect performance.

 

[QC]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Still sounds a little like water in the fuel to me. You said you checked the water separator and found no water. Did you replace it?

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I plan to do a compression test soon as pop drops off the tester. I have changed the water separator and on the lake I poured the gas into a clear clean bottle and it looked clean no water. When I done the carb rebuild everything went well, when I removed the carb, the bolts were not very tight and the gasket was rough so I thought for sure the rebuild fixed it although the carb. looked clean inside I thought maybe it had been pulling air in around the gasket. The last time out the gas tank near empty I filled it with the best gas. What would be the symptoms of a coil going bad? I am going to read more in my manual. Do I have an ignition module? I merely inspected the wires and dist. cap and points. The points looked okay, opened and sparked. It has been a few years since I have changed the wires and cap but not many lake hours. Thanks for the help yaw!!!!

 

[Lou C]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I had a serious performance problem on my OMC 4.3 and it turned out to be a bad antisiphon valve on the gas tank, they can rust and then the fuel pump can't suck fuel up through it. Worth a look. Also check the gas tank vent.<br />Other things to check--<br />spark advance on the distributor, you want to check timing at idle, and advance at 3000 rpm as per the manual.

 

[jmccall001]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I believe in the "float" test for plugs, If they float in water, they are OK, otherwise replace them. Had a similar problem with my sea ray, spark plugs were the culprit. Be sure to use the correct gap

 

[Boatin Bob]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

It did sound like the ESA possibly staying engaged although it sounds like you have tried to eliminate it. To be 100% sure though pull the 2 wire plug off (purple and grey wires) this will disconnect it for sure (just for testing purposes) Also there is another switch called the overstroke switch that prevents the ESA from engaging while in gear. Only takes a minute to eliminate it.

 

[marunr]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

If the shift cable is out of adjustment it will activate the ESA when it isn't supposed to. Do what Boatin Bob said to test the ESA. If the engine runs right with the switches disconnected you need to adjust the cable. The red one is the correct cable, the old one was black. If your shifter is hard to operate you are in danger of destroying your gears! You can see how to adjust your cables here:<br /> http://www.funkopolis.com:8080/~stuart/cobra/

 

[searay3]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I also have a 4.3LX 1987 vintage. Mine started acting up like that after a chance encounter with the lake bottom (rock). After much troubleshooting and painful frustration, a freind suggested the coil. No easy way to check it. It was a relativley cheap part so I replaced it. That was the issue. Prior to the coil replacement, whenever I tried to plane off it would backfire thru the carb and stall. Had to play with the throttle to keep it running long enough to get back to the dock. Seems wierd, but it now runs like a champ again. Maybe another piece of your puzzle...

 

[Don S]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I checked condition of wires, dist. cap,points, some plugs the easy ones to reach,

I think you may only need a tuneup, a complete tuneup, including a "Proper" compression test.<br /> How to, Compression test <br /><br />Replace, plugs, points, cap, rotor, wires if original, then set the point dwell, not just the gap, setting the gap is great for lawn mowers, not boats. Check the idle timing after the dwell, and make sure you are getting the proper advance timing. Adjust carb mixture and idle speed.<br /><br />If you think you may have a fuel problem, isolate the engine from the boat system and give it a try.<br />Just hook up a remote fuel tank (outboard tank) directly to the fuel pump and see if it works.<br /><br />You should also run a vacuum test on your engine after it's all tuned up to be sure there are no leaks, sticky valves etc.

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Thanks for all the help everyone!!! I will read over it and check the links provided. The best look I have had at my gas tank is when I had the carb off. Where is the antisiphon device? Where should I buy tune up items,wires,cap,Plugs,rotor etc. at my local marine shop or are these items the same as on a regular auto? Would the coil be bad and let the motor idle and rev out of the water? I don't have an outboard tank, can I use a length of gas hose and run into a regular tank of gas? When I rebuilt the carb, I counted the number of turns it took to bottom out the two idle mixture screws and replaced them the same number of turns. I did perform a fuel pump volume test and in 30 seconds I had more than half a quart, manual said to go for 45 seconds but I had to stop in fear of spilling. I know I am jumping from topic to topic and my lack of knowledge is apparent. I am really thankful and impressed at all who have responded to help me!!! Can I remove the drive without a hoist, maybe a strap over a tree limb. I know there is no substitute for the right tools and I don't wish to have to go to the hospital. Thanks again everyone, I will get to looking at the links provided.

 

[Lou C]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Antisiphon usually is right on top of the gas tank, there should be a cover or hatch you can lift up to access it. That was my problem a few years back.

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Thanks Lou, You have helped me before. But wouldn't the fuel volume test eliminate the antisiphon.

 

[Don S]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

How did you preform a fuel volume test? At speed, when the engine is hot? I doubt it, and that is where your problem is. Did you check the pressure? If it's low, the volume is low.<br />Like I mentioned earlier, isolate the boats fuel system with a remote tank and try running it under real world conditions. If the engine runs fine, then the problem is in the boats fuel system. If it doesn't change, then you can mark one complete system off your list as possible causes.<br />The purpose of troubleshooting in the beginning is to isolate a problem to Fuel, Electrical, and Air (including compression). Until you start isolating and eliminating systems you will be replacing parts and asking questions forever.

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I understand, I have allot of work ahead of me. I done the full pump volume test idling in the yard. I will run it off a second fuel tank. Lou, you have a very similiar set up, where would you purchase tune up parts? I have allot of issues. My shifting is very difficult, The thread on another post is being real helpful about the recall and adjusting shift cable. I have never removed an outdrive before, I am a printing press operator not a mechanic but I do get lucky sometimes and other times I get in over my head. Never rebuilt a carb before and when I got the kit and first looked at the instructions I thought maybe I should get a refund, but I figured it out with no reservations. I will do some testing. Thanks!!!

 

[rbezdon]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

DonWon, pulling the drive on this 88 OMC not too bad. I did it for the first time last week and I did the entire thing in about 3 hours including replacing the drive bellows and exhaust bellows, lube and check out of the exhaust paths. The drive is something like 80 to 100 lbs, manageable by your self but clumbsy but a breeze if you get a helper or build the out drive holder you can find on another thread on this site. Don't worry, these guys will get you through the work. If you have any experience mechanically it is just like the carb rebuild, possible with a little work and thought and advice for these pros.

 

[Lou C]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

I get the OE tune up stuff at an Evinrude/Johnson dealer. I use the AC marine spark plugs. I also replaced the wires as well with the OE stuff. Each year I do the points, plugs, condenser cap and rotor. Salt air gets to em here.<br />I totally agree with what Don S is saying <br />you have to start with the basics what does an engine need to run--compression, fuel (enough) and spark (enough and at the right time).<br />So get a good compression tester, warm up the motor and test compression. If good, then trouble shoot the ignition system. If good move on to fuel. One last thing, vacuum leaks can play havoc with engines too, although they are not that common, a leaky gasket under the carb can do the same thing.<br />I had a similar problem, I had good compression, ignition was good too, and carb seemed OK. Finally took it to the pro, he found debris in the carb, and bad antisiphon valve. He also fixed the shift system so I can shift with 2 fingers now. I take it to him each season to service the drive system and have had way less troubles this way.

 

[Donald Terrell]

Re: Tried several sugestions, need more please,1988 4.3 GM V6 OMC

Haven't done any testing yet. When I rebuilt the carb, I had to get a marine gasket which was 1/4 inch thich. There were 4 3/8" bolts holding the carb to the intake and one under the float bowl was very difficult to get a wrench on, all I didn't try was a 1/4" knuckle, any suggestions. The outdrive hasn't been removed since 96 when our local marine shop adjusted the shift cable. I am certain I need to lube the U joint although I haven't ran the boat much. I have a Cylmer manual, but I wish I something better. I haven't found anything on the bellows. I remember watching my father check for intake leaks by running a bead of oil along the mating surfaces but I don't know how to do a vacuum test. I don't do anything in a hurry, so I will try all these sugestions and let everyone know what's happeneing or ask more questions when I get in a jam. Lou, you said you use the AC marine plugs, what does the AC stand for? Auto Craft? I saw the pic of the wooden outdrive holder and the manufactured one, seems easy to build one. Thanks everyone, for all the sugestions.!!!!