1987 mercruiser 140

[bid2ask]

ok guys heres the problem, about two weeks ago i could not get the engine running, thought it was a bad fuel pump, so i cleaned the filter that goes in the carb inlet, poured a little gas down the carb and she fired up, now prior (about 2-3 weeks) it ran great, nice and smooth. now it has a little sputter at idle. i set the dwell on the points to 30 degrees, gapped the plugs to 35, set the timing 6 degrees btdc, and the miss is still there, i changed the cap, rotor, points, plugs, fuel water sep. about 1.5 months ago, anything im missing here, the only thing i did not play with was the carb. it was rebuilt last year. its got one mixture jet on its side, how many turns out should that be?

 

[jeff13601]

Re: 1987 mercruiser 140

Mine runs best about two turns out. I do not believe there is a standard set. I turn mine in until it starts to die and then I turn it back out until it does the same thing then I bring it back about halfway until I get the highest rpm. I am sure you will get other posts that explain it better

 

[Bondo]

Re: 1987 mercruiser 140

so i cleaned the filter that goes in the carb inlet,

What was in it ??<br />How Dirty was it ??<br />

fuel water sep. about 1.5 months ago

Pull it off again,+ Dump it out into a separate container,+ Look at it,...... <br />I Bet there's Water in it.......

 

[Don S]

Re: 1987 mercruiser 140

its got one mixture jet on its side, how many turns out should that be?

It's a Mercarb, and the final adjustment is done on the engine at idle. There is no specific number of turns.<br />To the untrained here is a way to get the adjustment very close.<br />With a shop tach hooked to the engine so you can see it, the engine warmed up, choke open and throttle cable disconnected. Set the idle speed to 700 - 750 rpm, then run the idle mixture screw in till the rpm starts to drop. Then back it out till you get the highest rpm. Back out another 1/8 turn. Readjust the idle rpm to 700 to 750 rpm.<br />Rev it up a few times to clear it out and go through the process again to make sure it'r right. If it backfires, it's either to lean or to rich. Adjust accordingly, and always keep the idle rpm at 700 to 750 rpm.<br />Do this till nothing changes and it all works.<br />Hook the cable back up and do a test run on the water.

 

[bid2ask]

Re: 1987 mercruiser 140

bondo, the filter was a littlt dirty just small particles if sediment, not that bad, i just rinsed it with some clean gas.

 

[bid2ask]

Re: 1987 mercruiser 140

don, i did what you said about the merc carb mixture screw, i got it as close as i can it idles a little ruff at @800 rpm, i changed the points, cond, cap, rotor, dwell is at 30 degrees, any other ideas on a ruff idle?

 

[bid2ask]

Re: 1987 mercruiser 140

don, i did what you said about the merc carb mixture screw, i got it as close as i can it idles a little ruff at @800 rpm, i changed the points, cond, cap, rotor, dwell is at 30 degrees, any other ideas on a ruff idle?

 

[jeff13601]

Re: 1987 mercruiser 140

Mine does the same thing and I have done everything but rebuild the carb. When it gets to the point where it really bothers me that will be my next step

 

[bid2ask]

Re: 1987 mercruiser 140

jeff, the carb was rebuilt last year.