1994 Mariner Mag. 40 Sudden Drop to 2000rpms

[Bilsboat]

I'm out crusing. Motor's running great.I'm between 4000 & 5200rpm's [but i,m not sure that's important]. 15min. to 1/2hr. into the run, the Motor suddenly drops to 2000rpm's +/-.<br /><br /> It sounds like the Motor is starving for fuel. If I throttle back it will quit. If I leave the throttle wide open, it'll run at idle [2000 rpms +/-]forever very smooth. If I shut it off, it will restart but I've got to choke it. In neutral, I can crank it right up to 5000rpm's. <br /><br />It has a high temp. sensor hooked up to the ignition controls. [a beep alarm]. The repairman I hired checked that out, and says it's ok.<br />I personally checked and cleaned the entire fuel system, from fuel tank, hoses, filters,etc. right to the carburaters...nothing.<br />Where were at now is, the repairman pulled both carburators apart and said he found a grain of sand in one of the high speed jets. I personally, although I hope this solves the problem, but I don't think it will.<br /> I'm going to test it again this afternoon.<br /> To all interested, I will keep you posted. Meanwhile, I sure do hope that someone out there has some information that will help me out.<br /> <br /> Thank you very much<br /> Bill

 

[rickdb1boat]

Re: 1994 Mariner Mag. 40 Sudden Drop to 2000rpms

Sounds like you may have dropped a Cylinder. Check for good spark and check compression. I also doubt that the Carb. is your problem!

 

[Bilsboat]

Re: 1994 Mariner Mag. 40 Sudden Drop to 2000rpms

re Mariner Outboard Drops to 2000...<br /><br /> Well Rick, fortunatly it dosen't seem to be anything as dramatic as a dropped cyl. If i'd dropped a cyl. that old Mariner would be hopping all over the transome but it runs smooth as a baby's butt.<br /><br /> So far, the problem appears to be the grain of sand that I mentioned. Apparently the sand grain was being sucked up into one of my high speed jets after 15min to 1/2 hr. of running,causing the jet to plug thereby dropping my power by half. Then after the motor set awhile, the sand grain would fall out of the jet and drop back into the carb. sediment bowl, where it would lurk like an evil little beast until I started and ran the engine again. Then it would gradually work it's way back up into one of my high speed jets, to do it's evil deed again.<br /><br /> After a fierce battle, my Mechanic killed and removed the little beast, and since then [so far] my '94 Mariner Mag. 40 is purring like a kitten!!!<br /><br /> Bill