What's with the engine?
 

Here's what's happening:

Cruising along ......doesn't seem to matter what speed or rpms.... everything is peachy...

engine slows down...you can hear it....rpms & speed drop
engine picks back up and is fine again

engine slows down.....

engine picks back up...

this happens over & over... from anywhere from 30 seconds to 5 minutes or so

then it stops doing it all on it's own and acts like it never happened in the first place

If it was a car it would sound like a low rev....count to three or 4...then foot off the accelerator...then low rev...count...then foot off...repeat until insane

99 Merc 5.7 about 120 hours on it

all normal maintenence is done on an ongoing basis

Got a once over last month while it was getting the new ignition installed last month. The wrenchers didn't see anything else that needed to be done.

Possibilities? Ideas? Guesses?



:confused: :confused: :confused:

Fuel filter?

does it idle smooth? If idle surges also, it is probably a bad ECM. if thats ok I would put a fuel pressure guarge on it you could see while it was acting up.

He pulled the filter and said there was stuff that didn't look like "gas" stuff on it.......... he rinsed it in gas and we'll see how that does today...

He said it idles smooth the whole time and if getting a new fuel filter tomorrow doesn't fix it we'll grab a gauge to check it while we're in the water.


Wer'e up for any ideas and will check anything that anybody can come up with to figure this puppy out

A friend of mine had a similar situation. They ended up removing some sort of a check valve on top of the gas tank. I think it's supposed to stop fuel flow if the boat turns over. It went bad and was closing off the fuel anywhere above idle.

The solution in the filter was probably the result on gasahol. Early season gasoline deliverys containing alcohol can stur up and emulsify the water and crap in the dealers tank and deliver it to your fuel tank. You many have to get the tank and the whole system cleaned out. Consult the dealer. We had a dozen boats needing some major work last spring. The companys picked up the bill.
JB