Merc 140 still bad behavior after carb rebuild

[jennis9]

1985, Merc 140, 4cyl -- I/O

1. Action: engine completely stopped three miles after launch at 27mph - motor would turn over but not start

Fix: new sprk plugs, plug wires, distributor cap, rotor and points. fuel filters clean, gas tank full and clean fuel

2. Action: motor starts and idles perfectly, runs normal at no wake appx 5mph - would not power when throttle is engaged forward (bogs out) - checked both gas filters again - checked gasoline for water (negative) -- checked to make sure intake vent was not blocked - then carb begins to spit gasoline

Fix: fuel line tested per mechanic - rebuild carb - replace gaskets and float and lower gas line.

Getting compression but the engine is still bogging out - won;t go past 5mph - compression at each of the cylinders is 120. Our mechanic is perplexed and cannot figure this out. Any suggestions?

 

[Don S]

Re: Merc 140 still bad behavior after carb rebuild

Rebuilding a marine carb, especially if it had a lot of water and corrosion in it, is at best a 50/50 chance of working. Some of those passages just can't be cleaned out with normal methods.

 

[jennis9]

Re: Merc 140 still bad behavior after carb rebuild

Should we try a new one then? Is there a way to test it?

I did get a look at it and it was shiny -- would there be a sign of corrosion to look for?

thanks don

 

[APPALOOSA2]

Re: Merc 140 still bad behavior after carb rebuild

You said motor stopped and would not turn over ? Or do you mean the engine would turn over and not start ?
Was the engine hot ?

 

[jennis9]

Re: Merc 140 still bad behavior after carb rebuild

You said motor stopped and would not turn over ? Or do you mean the engine would turn over and not start ?
Was the engine hot ?

no - it was like someone just pulled the key --- nope it was not hot. we had only been motoring out for about ten minutes. no gas smell - electric was still working, radio, nav lights, horn... like someone yanked the safety lanyard (only we don't have one)

yes, it would turn over but not start. after the new points and cap went in it started up and idles great. then it started spitting gas - but not initially - it would bog out - and we tested the fuel system and rebuilt the carb/float.

just cant get it to run over 5mph now....

seems like once we get one thing fixed, another issue arrises.

 

[bigred69]

Re: Merc 140 still bad behavior after carb rebuild

Sounds like ignition to me. Possibly a coil or two. Had same problem on my 50. Found two coil wires from switch box not making good enough connection.

 

[jennis9]

Re: Merc 140 still bad behavior after carb rebuild

bigred -- looks like you may have hit on it.... our guy is calling in the heavy artilliary: a guy named DW.

You know when he comes over with his bag of tricks - you're going to get answers. He suspects ignition too.... I'll keep you posted. Thanks for the replies.

 

[bigred69]

Re: Merc 140 still bad behavior after carb rebuild

No problem. Let me know what ya find.

 

[JustJason]

Re: Merc 140 still bad behavior after carb rebuild

So... just so where on the same page.... What is your dwell set at in degrees, what is your base(idle)timing set at, and is it advancing when you rev the engine?