140 mercruiser fouling plugs

[bishop12]

Hello, I have a 1980 dixie with a 140 mercruiser I/O engine. My problem is that it keeps carbon fouling all of the spark plugs. I have rebuilt the carb and adjusted the timing and still no luck. Im am not real sure if I have the timing correct 6degree btdc is where I think that I had set it at.The carb has a drip inside after the engine is shut off. The motor will blow black smoke the clears out after a few seconds. It seems to run ok every where accecpt at idle(rough). any help would be apprecieated.

 

[damie]

Re: 140 mercruiser fouling plugs

i had a problem with rough idle and noticed fuel dripping into throat of carb when engine stopped,this turned out to be a corroded float needle seating,just letting a small amount by.<br />when engine running with load plenty of fuel was being used so fuel bowl wasnt over filling,but at idle it caught-up with its self and over flowed into throat,causing a very rich mixture.<br />hope this helps

 

[damie]

Re: 140 mercruiser fouling plugs

if carbon is building on plugs you can be shure that it is also on pistons and valves,this will glow,and when engine is shut off along with fuel dripping into throat could cause the engine to run on and create a blow back through carb,like you mentioned,i doubt that the timing would cause this.

 

[bishop12]

Re: 140 mercruiser fouling plugs

Thanks for the reply.Im pretty sure that there isnt any thing in the carb causing the drip but i will check again. At the filter located on the inlet, it had a small black rubber thing that had a spring in it that was suppose to slide into the filter(lost it) would it have any thing to do with it.Also My book sais to time at 6degree btdc @ 750 rpm idle. How do you achieve this when you advance the timing the idle will move the idle with it.

 

[Trent]

Re: 140 mercruiser fouling plugs

First off......If you have fuel dripping after shut down you HAVE A PROBLEM. You need to check the main jet needle and seat. Did you set the float level correct? <br /><br /> Carb <br /><br /> web page

 

[loadnet]

Re: 140 mercruiser fouling plugs

Biship12 - Listen to Trent...<br /><br />If you can't fix the main jet in the carb and reset the float correctly no problem but take it somewhere and get it done.<br /><br />Step 1) Stop the excess fuel from dripping into the carb at shut down and idle rpm.<br /><br />You'll see a terrific difference in how your engine runs at idle, and how it starts after warm up once you've stopped the drip..<br /><br />Take care,<br />PB

 

[bishop12]

Re: 140 mercruiser fouling plugs

Think I have it this time. Re adjusted the float and it runs like a champ. Although it has a little popping thru the carb at high rpm. Any suggestions?

 

[DJ]

Re: 140 mercruiser fouling plugs

bishop,<br /><br />A "pop" means lean mixture. You may have gone a little too far on your float adjustment.<br /><br />Also, look for crossfiring spark plugs. Look for "lightening" from your plug wires when viewed at night.<br /><br />Carbon tracks on the distributor cap and/or rotor will also cause crossfire.

 

[Bondo]

Re: 140 mercruiser fouling plugs

You need Either a Propperly Rebuild,+ Adjusted Carb...... Or a New Carb, that's Propperly Adjusted......<br />I'd say your Carb has alot more Problems than You can see....