1974 Mercruiser 140hp 4cyl - won't idle for long

[HeliBoater]

I've read almost every post relating to this subject and I must say I am getting a great education. Thanks for a great site. I'm a newbie boat owner. just bought a 1974 17' Bayliner with 140hp Mercruiser Stern drive (4cyl, 2bbl carb, 2 mixture screws). "Rebuilt" drive and engine. gas tank sat full for the winter.

Here's my problem, I think it's a simple one: engine will start, engage drive, and rev to 5,000 RPM smoothly on the water. But it won't hold an idle for longer than 20-30 secs and the idle surges like its getting either flooded or starved of fuel at intervals. I've replaced plugs, filter, and even ran the line through an electric fuel pump for comparison - no difference. points/rotor look new. plugs were blackened but no buildup.

I'll WD-40 the carb base to look for vacuum leaks.

Can you suggest anything else?

Also, what does WOT mean?

BIG thanks for any information you can provide.

 

[Wakesilver]

Re: 1974 Mercruiser 140hp 4cyl - won't idle for long

WOT=wide open throttle

 

[HeliBoater]

Re: 1974 Mercruiser 140hp 4cyl - won't idle for long

Thanks Bubba. I'll do just that.

Thanks wakesilver for the definition.

Appreciate the help

 

[P 0 P E Y E]

Re: 1974 Mercruiser 140hp 4cyl - won't idle for long

How old are the points and condenser?

I would change the points and co denser, inspect the distributor advance, Make sure the timing is in the ball park.

Then go for the carb cleaning.

 

[HeliBoater]

Re: 1974 Mercruiser 140hp 4cyl - won't idle for long

yes sir. The points and condensor are new. Haven't checked the timing yet, but will do that as well.

thanks