1500 Mercury driving me crazy

[wired247]

This thing is driving me nuts. Got it out on the water yesterday. No power at all on the bottom end. Full throttle off idle it either dies completely or hits 1500 rpm or so and sits there forever even at WOT. I was able to feather it up until it hit 2200 RPM ( took 3 minutes ) then it took off like a bat out of hell. WOT without feathering it it it just makes the chirping reed sound and dies or runs at 7 MPH all day.

Here it is running at just shy of 5800 RPM and 59 MPH

http://www.youtube.com/watch?v=mOMeU_JQSAI&feature=youtu.be

That was yesterday. Today I couldnt even get it on plane. rebuilt pumps and pumping the ball does nothing. CDI switch box, new plugs and cap. CDI pickup. pulled the plug wires and checked the spark.One minute it has 1/8" spark and then next its throwing 3/4".

21 degrees BTDC at full throttle. 8 degrees BTDC at idle. Won't idle at any less. 1 turn open the idle screws. Won't idle at any more. 125 PSI on all cylinders. I can't figure out if its a carburetion problem or a ignition problem. Ive set the floats a dozen times and theyve been thoroughly cleaned, new needle and seats etc. Acts like carbs and it acts like ignition. Sometimes I can way over advance the ignition and it runs barely OK and the next it doesnt.

 

[iamtheguy]

Re: 1500 Mercury driving me crazy

I am a complete novice but it sounds like carbs to me.

Maybe something got into the main jet?

 

[wired247]

Re: 1500 Mercury driving me crazy

Three carbs, three main jets. If I can get it to plane it runs like a scalded raped ape. Otherwise it has no power under 2400 rpm whatsoever.

 

[Sunfish12]

Re: 1500 Mercury driving me crazy

Could be the low speed coil on the stator, need to test with dva adapter to know for sure. The adapter is cheap and can be used with a digital meter.

 

[Georgesalmon]

Re: 1500 Mercury driving me crazy

try opening the idle jets another 1/8 - 1/4 turn. Just one carb at a time.

 

[Faztbullet]

Re: 1500 Mercury driving me crazy

Could be the low speed coil on the stator

Sorry but this is a battery CD ignition....does not have a low/high speed stator....

One minute it has 1/8" spark and then next its throwing 3/4".

Check the carbon tip in distributor cap, voltage to switchbox and coil for cracks that open up when warm. Setting on carbs is 1-1/2 turns off light seat.

 

[kazek]

Re: 1500 Mercury driving me crazy

see if throtlle cable accually moves past high idle.mine was not going past that spot and was going outstide the track in the merc control.just a thought

 

[wired247]

Re: 1500 Mercury driving me crazy

Had fiber reeds in it and they were nowhere near seated. That and the hokey ball hone of the worn out scored cylinders and no amount of carb tuning was going to do squat. So I picked up a new NOS service block, reinstalled the steel reeds in the cages and a new set of pistons. I even picked up a new service crank just to tighten things up a bit in the labyrinth seal area ( and I had a slightly damaged rod journal ) . Should be all back together next week. Just like having a new engine.