Mercruiser 4.3L won't start

[Tamas1975]

I sucked out all the old gas and put brand new gas in there. I put the old rotor and cap back on and it still wouldn't fire up. When I tapped the white green wire to mass I got sparks (bottom troubleshooting check).

 

[alldodge]

If your getting spark to all plugs then it should fire

Pull plug 1 and put your thumb or finger over the plug hole. Bump the starter until your thumb gets pushed out (this is TDC number one).

Check position of the rotor to see if its point at or close to number one. If not real close move the plug wires so number one is close or remove and reinstall distributor. Then try to start again

If no start, check spark at the plugs with gap tester or at least with plug removed and grounded against block

If spark is present then it has to be gas. Put just a little dribble of gas down carb

 

[Tamas1975]

Pored fuel into the carb, but she won't start. I do have some spark, but not very strong (see video). I will put new spark plugs in (came with the boat). Then the new sensor if needed.

 

[nola mike]

Pored fuel into the carb, but she won't start. I do have some spark, but not very strong (see video). I will put new spark plugs in (came with the boat). Then the new sensor if needed.

Are we seeing evidence of spark in the video? Didn't look like it's trying to start at all.

 

[stresspoint]

is the lanyard key in place , is the shift in neutral " sometimes you have to click them about a bit if the boat has sat "".

start off going over the simple stuff first before swapping stuff out .

you say "" i bought this boat "" ? had it ran in your possession before this no start occurred

 

[alldodge]

Missing spark

 

[Tamas1975]

Yes got spark, at the bottom is the plug from cyl 1 but it's 3 sec between sparks, instead of 4 per second with around 500rpm starting

 

[Candy Gramformongo]

You could also try starting fluid. It's usually a last resort, but this might be the proper situation for it. Have the fire extinguisher handy.

 

[Tamas1975]

Tried starter fluid already too. I am not sure when the boat ran last (before I bought it). Will get a new ignition sensor and change the plugs. Might take a few days though... will update once I swap those parts

 

[Candy Gramformongo]

Based on the spark I see in your video, it should run if only briefly on starting fluid. I would check next if you have the spark plug wires on in the correct order. That is about all that is left that it could be.

 

[nola mike]

Are we seeing evidence of spark in the video? Didn't look like it's trying to start at all.

I didn't even see you holding that plug at the bottom lol. That spark looks weak as well. Next step I'd do is to put a tester or plug on the coil wire and see if the spark is better/faster

 

[Scott06]

Agree looks weak and also seems like it is cranking slow. Wonder if battery is dead or corroded terminals are causing a voltage drop as it doesn't look like it is hitting spark often enough nor strong enough. I would measure volts when cranking at coil willing to bet is is low

When I did my repower with a new TB system on it had a nice blue/white spark that could jump 3/8" at least. You could hear it snap.

 

[stresspoint]

+1 have the battery checked oe swap it out for a known full power one , these motors take a a lot of cca to fire them up .
on that note the starter could have an internal short causing slow crank and taking power from the ignition.

 

[Tamas1975]

Hi all, I changed the ignition sensor and did the spark plugs. It definitely helped to where it almost started. Recharging the battery overnight and trying again. Attached is the pic of the old plugs.
Found the engine number: 0772085.