mercruiser 140 won't start. Help

[sti1471]

OK I have a very strange problem.

I have a boat that has been sitting for a few year that has not been started. It is a 1986 mercruiser 140 3.0L.

when I turn the key, the engine rotates just fine. however it just sounds like an engine that has no spark as all. I spray starter fluid in the carb and it makes no change. I have removed all spark plugs and turn the key, the engine rotates and I can see all 4 spark plugs sparking. The spark plugs are black (cold Fouled) but they are still creating a spark I can see in the daylight so that should be fine.

I have checked the firing order and it is set to 1,3,4,2 with point 1 pointing to spark plug #1. But here is where it gets weird.

I remove spark plug #1 leaving 2,3,4 plugs in the engine. When I turn the key, the engine rotates, but then almost acts like it wants to start every 4-5th rotation but never does. When I pull plug 1&2 leaving 3,4 installed, it acts like it wants to start every 3-4 rotations but never does. When I put all 4 spark plugs back in the engine and try, it acts like it wants to start for a minute or so, but then goes back to just rotating with no signs that it has spark at all.

Has anyone ever seen or heard of this before?
Any help would really be appreciated.

 

[Don S]

Re: mercruiser 140 won't start. Help

Pull the coil wire out of the center of the distributor cap, hold it about 3/8 to 1/2" away from a clean ground (no paint) and crank the engine. You should have a blue/white spark that snaps across that gap. If not, or if it's yellow. Replace the points and condenser.

 

[matt167]

Re: mercruiser 140 won't start. Help

Check the bottom of the distributor cap for carbon arching. Once I spent 2 days trying to get my 1951 Chevy ( Factory 6cyl ) running. I had pulled it to the side of the driveway, shut it down and it would not restart. got a pop once in a while but nothing else. checked for spark and it was there. After new points and condensor, I replaced the coil and rotor but not the cap and it still would not fire. After finally checking under the cap, I found carbon arching everywhere and after a new cap, it fired right up.

As Don says, points and condensor are usually the main culprits to no starts

 

[tinkerguy70]

Re: mercruiser 140 won't start. Help

Has anyone ever seen or heard of this before?
Any help would really be appreciated.

Yes, and after 2 days and going through the points, condenser, coil, wires, and everything else, it ended up being bad spark plugs. Spark Plugs that had maybe an hour on them at most, but had been installed, then the boat was stored for 3 or 4 years.

I would have never have thought it, but after 4 new plugs, the motor fired up after three of four turns of the starter.
Not saying this is your problem, but if you still have problems after checking everything else, you might try the plugs.

 

[sti1471]

Re: mercruiser 140 won't start. Help

So I know this might be a dumb question, but if the plugs are sparking, and there is starting fluid in the carb, why would a bad condenser or arching cause it not to ignite the starting fluid?

 

[Bondo]

Re: mercruiser 140 won't start. Help

The spark plugs are black (cold Fouled) but they are still creating a spark I can see in the daylight so that should be fine.
So I know this might be a dumb question, but if the plugs are sparking, and there is starting fluid in the carb, why would a bad condenser or arching cause it not to ignite the starting fluid?

Ayuh,... Bad spark plugs, 'n Bad ignition components might spark in the daylight, but daylight ain't under Compression either....

There ain't no Easy Button,...
Yer motor needs a serious Tune up if it's gonna run right....

 

[dubs283]

Re: mercruiser 140 won't start. Help

There ain't no Easy Button,...
Yer motor needs a serious Tune up if it's gonna run right....

yep,

sounds like a FULL tune-up is in your future

click on the link here:

http://forums.iboats.com/mercruiser...ne-up-your-engine-points-ignition-335302.html

 

[tinkerguy70]

Re: mercruiser 140 won't start. Help

So I know this might be a dumb question, but if the plugs are sparking, and there is starting fluid in the carb, why would a bad condenser or arching cause it not to ignite the starting fluid?

Yeah...my plugs were too....but they where still bad.

If you want to save yourself a lot of time and headache, do as the others have suggested and do a complete tune up.
Trust me, you'll save so much time and heartache that the extra cost will be well worth it in time and sanity savings.

 

[sti1471]

Re: mercruiser 140 won't start. Help

Yeah I plan to do a full tune up, but I want to get it started at least to make sure no damage was caused by sitting for years unstarted.

Today I checked tdc, adjusted as needed and gave it a go. The engine was closer to starting than ever. It actually started for a seconds or so but then either choked out or burned all the starting fluid out.

However I did do the test mentioned above by Don and the spark from the coil wire to bare metal was intact yellow/orange. So I am going to replace condenser and points to start. Could the yellow spark be caused by the coil going bad?

Can I replace the condenser with any condenser or does it need to be mercruiser, or marine?

 

[matt167]

Re: mercruiser 140 won't start. Help

Your condensor very well may cross to a non marine specific part. Napa and Carquest both have marine catalogs that you can look thru and see.

IIRC my dad always bought points/condensor for a Chevy truck with 250 I6 for his 3.0L and they worked but, his was a '73 boat and likely had a different distributor

 

[dubs283]

Re: mercruiser 140 won't start. Help

Yeah I plan to do a full tune up, but I want to get it started at least to make sure no damage was caused by sitting for years unstarted.

Today I checked tdc, adjusted as needed and gave it a go. The engine was closer to starting than ever. It actually started for a seconds or so but then either choked out or burned all the starting fluid out.

However I did do the test mentioned above by Don and the spark from the coil wire to bare metal was intact yellow/orange. So I am going to replace condenser and points to start. Could the yellow spark be caused by the coil going bad?

Can I replace the condenser with any condenser or does it need to be mercruiser, or marine?

coils rarely go bad, sometimes they do get weak and fail but more often than not a good coil is tossed in the garbage because it is easy to replace one

start with a tune-up kit, they come with a point set, condenser, and rotor that should get your engine started - then you can check for the damage you are concerned about

you can get tune-up kits right here on iboats for your specific distributor/motor

have you looked at the link i posted earlier??

also, check the adults only section or the diy info section (stickys at the top of the forum page) good info there