won't keep WOT

[PuckHog]

I have a '78 Merc 800 80hp ser. # 5006360. It's mounted on a '69 Glastron 15' open bow tri-hull. When I start from a stand-still sometimes I get a great hole-shot, other times the motor fades out. After I put it back in neutral (restart if it stalls) I can gradually get it up to 2000rpm, then it takes off like a rocket. Either time, it climbs to 5400-5500rpm when I get on plane then fades back to between 5100-5200rpm WOT. I don't dare tilt the motor any further out for fear of too much bow lift (manual tilt amd I'm at the fourth hole out). I tried to do Clams' timing and sync, but some clown before me wiped off the timing marks (another project).

 

[marinegrh]

Re: won't keep WOT

tdc your engine, top dead center it. then reset your timing..Almost sounds though like either bad fuel delivery or reeds....id check fuel output first, and when was the last time you had your carbs cleaned...mmmmn am i getting you to think a little...process of elimination. no trying to be a smart *** by anymeans, i like to help people but also get them to help themselves and it make your boating more fun..I am also wondering about your fuelpump, it may have holes in the diaphrams or the check valves are worn out...just a few thing to check first, repost with you results and ill see what i can do if those dont help

 

[GA Paramedic]

Re: won't keep WOT

If I am not mistaken, you should be able to find a timing sticker to put back on your fly wheel. As long as you get TDC in line with TDC on your new sticker, shouldn't been any problem. Just make sure the new sticker has the correct degrees for your timing specs and is calibrated for your size of flywheel to where 1 degree does infact equal 1 degree on your flywheel. The marks aren't magical except for being exactly relitive to TDC. Not just the fly wheel. Just don't trust any marks of where the old marks were just in case the flywheel was removed and not replaced in the exact position.

 

[PuckHog]

Re: won't keep WOT

Thanks for the replies. I removed and thoroughly cleaned both carbs and replaced the check valves, springs, and diaphragm for the fuel pump. <br /> The mark for max. advance (27 degrees) is still legible, so I figure I'll measure the circumference of my flywheel where the marks are , divide it by 360 and measure over to TDC. Then I'll have to use a dial indicator to establish TDC and check my timing pointer because it is also adjustable. Then I can check my timing.

 

[PuckHog]

Re: won't keep WOT

Meant to add I did the carb cleaning and fuel pump work prior to posting.