Intermittent Problem - need ideas!

BuilderFL

BuilderFL

Junior Member
Motor was working poorly, assumed that I had a power pack or coil problem (which I’m getting thru bigshrimpin), however I cleaned the carburetors and she started up right away, with higher rpm that it’s had been set at. I figured, the cleaning did her good. For good measures, a replaced the fuel pump diaphragm kit, the fuel filter/water separator, adjusted the rpm to 900 and the motor was working perfect. Took her out yesterday, nice idle rpm at the ramp and she ran like never before, doing about 42 mph, which for a heavy boat like mine, it’s very good. Ran for about half an hour and when I reached a no wake zone that I slowed down, the motor turned off. She would start, but it would not go beyond 1,200 rpm. Every time I tried, she would bog down. I did notice that if I pressed the choke while running, she would increase rpm rather than decrease. Pushing the choke off and on in 15 seconds intervals, she would gradually increase the rpm to running speed, however the rpm would intermittently drop and go back up by about 300 rpm. I did make it back to the marina and she would not idle, increased the rpm and noticed that she would start, but the moment I put her in gear, she would shut down. She started again back at home, but sounds like it’s running at reduced power.
Any ideas? :head:
1989 Mercury 200HP
Thanks,
 
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Sounds fuel related (starved for fuel) . . . like the Anti-siphon is bunged up or you have water in fuel (fuel water separator is full) . . . before you mess with the motor . . . Try running off a 6 gallon tank with fresh fuel and a new hose/bulb and see if there is any difference.
 
check the fule filter and then get some one to pump the bulb while its running to see if it will run OK(indicates fuel pump or restriction)
 
I will try the 6 gallon tank with fresh fuel and a new hose/bulb and get back with my results. By the way, if there a way to test the bulb? My water filter separator has a bottom bowl that can be drained, which I have done several times without any change in performance. Should it still be replaced?
 
BuilderFL said:
I will try the 6 gallon tank with fresh fuel and a new hose/bulb and get back with my results. By the way, if there a way to test the bulb? My water filter separator has a bottom bowl that can be drained, which I have done several times without any change in performance. Should it still be replaced?
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Could still be clogged. This ethanol in the gas is screwing with everyone's performance.:cry:
 
Draining the bowl is for getting rid of the water that might build up, but the filter is to clean the dirt and will clog in time, always start the season with a new filter and carry a spare!!
 
Could be stuck check ball in fuel tank depending on type of tank you have. I have above deck side tanks and we just took the check ball out because they great for sticking.That was on my V20. I also had problem on small boat with 50hp wouldn't idle but if sped up would run but run like ****. It was dirty porcelain on outside of plug. Wires were firing over outside of plug to ground and had bad gas on top of that.
 
BuilderFL said:
I will try the 6 gallon tank with fresh fuel and a new hose/bulb and get back with my results. By the way, if there a way to test the bulb? My water filter separator has a bottom bowl that can be drained, which I have done several times without any change in performance. Should it still be replaced?
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What's the good word? When you run the 6 gallon go straight to the motor and use a different hose/bulb/fitting. Also was the engine Hot when it stall out?
 
First let me say thanks to Macojoe for setting me up with Bigshrimpin and the spare power packs he sent me. :clap:
The six-gallon tank solved the issue. As it turn out, you guys were right...tons of water in my tank and the motor was starving for fuel. I figured, (of course, we are all geniuses in hindsight) that since water is heavier than gasoline and that the two don’t mix, the water sits in the bottom of the tank were the fuel pick up is located. And no matter how much fresh fuel you add, the water will still be there. Anyway, motor is working fine, can't get it to idle at 850 rpm, but 950 is good with me. Now I have a clean carburetor, new fuel filter, clean fuel and two replacement power packs installed. Got out on Saturday, ran all day without any issues and although I did not catch the Dolphins I was looking for, I did land a mean 4’ barracuda that went back in the water after a stressful hook release.
Again, thank y'all!
Bill :beer:
 
BuilderFL said:
First let me say thanks to Macojoe for setting me up with Bigshrimpin and the spare power packs he sent me. :clap:
The six-gallon tank solved the issue. As it turn out, you guys were right...tons of water in my tank and the motor was starving for fuel. I figured, (of course, we are all geniuses in hindsight) that since water is heavier than gasoline and that the two don’t mix, the water sits in the bottom of the tank were the fuel pick up is located. And no matter how much fresh fuel you add, the water will still be there. Anyway, motor is working fine, can't get it to idle at 850 rpm, but 950 is good with me. Now I have a clean carburetor, new fuel filter, clean fuel and two replacement power packs installed. Got out on Saturday, ran all day without any issues and although I did not catch the Dolphins I was looking for, I did land a mean 4’ barracuda that went back in the water after a stressful hook release.
Again, thank y'all!
Bill :beer:
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Congrats on gettin' your problem solved!!...have you figured out how the water got in the tank to begin with?...I remember it a real beauty, but can't recall your boat's year model...earlier ones like mine had the fuel vent BELOW the rub-rail...I relocated mine ABOVE the rail after taking water several times...
 
Nice job Builder! It sounds like you have a racor separator. I have one with the clear bowl and drain at the bottom. I'm of the opinion one should drain it before each outing. A good thing to do would be drain it into a clean mason jar so you can see the amount of water/trash in your system. I also dump the inline filter on the motor pretty frequently as well. There always seems to be tiny specs of trash in the bottom....I guess its doing its job!

Congrats!
 
Reel, I believe you are right on the money with the location of the fuel vent and how the water gets in the tank. Mine is a 1980 and does have the fuel vent below the rub rail. Motor has been running like champ, however I went out today and the seas were 2'-4' and although that Carolina flair displaces water nicely, a lot does come up the sides, were the fuel vent is located. Sure enough, by mid day, I was having performance troubles again. Water in the fuel.. When I got back, I ran the motor on my new 6 gallon tank and after burning the brackish fuel from the carbs, she was up and running normal. Before I make a new hole on the fiberglass, I'm going to install a new temporary vent on the cover of the inspection hatch that I have on the inside by the fuel cap and leave the existing vent with a short hose connected to a small container to go out and test the theory. Will keep you posted.
 
we have a harbor master boat up here not a V20 but they have the same problem, they installed a SS Clam shell over the front of the vent, never a problem again.
 
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Shouldn't it be ok as long as you have the big loop in the vent hose? Mine is below the rubrail and I've never noticed any water in the fuel...just asking. I don't even know if mine has the loop. I'll take a look next time I take the rod box out.
 
Problems

Isn't it amazing what asking for help on these forums bring! I also have learned something new! Just a little thing like where the vent is located will have such a big impact on performance! And a simple fix.
This is such a great place to get help, thanks to all of you, you make things much easier fior all the rest of us!!

Tommy:sun:
 
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