1995 Mercury 150 EFI issues

[Capt. G]

Hi everyone,

I have a 1995 Mercury 150 EFI on a 1995 Cajun bass boat. The first time I had it out this season I made a long run on LOZ. On the long run the RPMs would surge at high engine speeds. If I lowered the RPMs below 4000 it would run smooth.

I just had a chance to get back out this past Monday and Tuesday. On Monday morning it didn't want to start at all. It would turn over just fine but wouldn't fire. Once it did start it idled fine no problem. Im wondering if water got into it because of all the rain. We made a small run and it still surged in the high RPM range but no other problems.

Things got worse on Tuesday. It started and idled just fine however it was very underpowered. At full throttle it was hard to even get it up on plane. While trying to get it up on plane it surge really bad from 3000 to 5000 RPM. It also used A LOT of gas.

Any help or ideas would be great. If you need any other info please ask Ill try to provide as much as I can.

Thanks

Greg

[WeekendWarrior]

water in gas, plugs, or ready to spin a hub? Fishnwrench is a boat mechanic and will chime in

[Capt. G]

^{I guess water in gas is a possibility. When I come off plane the back of the boat does get wet and Im sure water gets into the fuel vent. I put new plugs in it. I will check them to see if I can see anything abnormal. I will also check the hub.}

^Thanks

^Greg

[dtrs5kprs]

water in gas, plugs, or ready to spin a hub? Fishnwrench is a boat mechanic and will chime in

Pretty good guess that it is a fuel issue. Might run some stabilizer and quikleen through it with some fresh gas, then fill and re-treat.

[fishinwrench]

Water in fuel should give you a warning beep on that engine.

No sense in guessing, if you are still in the LO area and want me to diagnose it gimme a call.

573-569-5406

[Capt. G]

I'm not in LO area at the time. I live in the STL area. I will be back there July 4th weekend and the weekend after that.

Greg

[Capt. G]

Thanks everyone. Fishinwrench when I'm back in the LO area I'll give you a call.

Thanks

Greg

[fishinwrench]

That's cool. There's just too many things it could be for us to start sending you on goose chases.

I can narrow it down to heart of the issue in about 30 minutes if I could lay hands on it.