96 mercruiser 4.3lx won’t start.

[brunolund]

96 lund tyee, 4.3 LX mercruiser. 0F294871.
i pulled motor out of boat 1 1/2 years ago, to rebuild boat. everything is reinstalled now, and i can’t get it to start. the outdrive is off, but i only want to fire it up and not run for any time. as far as i can tell the wiring is all correct and working. the motor ran fine before removal, and i just did compression check to ensure no stuck valves. the distributor was not removed from motor. i have checked the firing order numerous times!! i does seem like that is the problem, but i’ve checked and rechecked it over and over. i just tore carb apart, and it is perfect.
the motor turns over great, but i’m getting backfiring through the carb. fuel is new. tank was drained completely during rebuild, and filled with fresh fuel two days ago. carb had good fuel in it when i tore it open. spark plugs are new and gapped correctly. any suggestions would be great as to where to go now.

 

[brunolund]

i guess what i’m thinking, is either there is a problem with the wires on the control box( commander 3000?), or ive miss wired the distributor somehow?? i have the wiring diagram, so will check what i can. i figured if it was backfiring the distributor is working properly, even if out of time. looking for which wires to check i think.

 

[poconojoe]

Lanyard kill switch? Does your boat have one?

Did you check for spark at the spark plugs?

 

[brunolund]

i was thinking that, but would that allow it to fire at all? my lanyard piece is broken, but has been since i got the boat 15 years ago. can i just connect wires together to bypass it?

 

[brunolund]

to clarify, my controller has what i believe is a lanyard switch( just two brass terminals currently), as well as a separate on/off switch. the on/off switch was working before rebuild, lanyard was never actually there, but boat ran fine without it. if anyone has suggestion on how to test those, i’ll do that tomorrow

 

[Bszakaly97]

96 lund tyee, 4.3 LX mercruiser. 0F294871.
i pulled motor out of boat 1 1/2 years ago, to rebuild boat. everything is reinstalled now, and i can’t get it to start. the outdrive is off, but i only want to fire it up and not run for any time. as far as i can tell the wiring is all correct and working. the motor ran fine before removal, and i just did compression check to ensure no stuck valves. the distributor was not removed from motor. i have checked the firing order numerous times!! i does seem like that is the problem, but i’ve checked and rechecked it over and over. i just tore carb apart, and it is perfect.
the motor turns over great, but i’m getting backfiring through the carb. fuel is new. tank was drained completely during rebuild, and filled with fresh fuel two days ago. carb had good fuel in it when i tore it open. spark plugs are new and gapped correctly. any suggestions would be great as to where to go now.

Motor needs spark fuel and compression at the right time. Get a cheap spark test from harbor freight (under 10$) check each line and make sure every cylinder is getting spark. Assuming you’ve looked into the throat of the carb and that your getting good sprays and enough fuel this sounds like a timing issue to me. But first you may check your KS.. my merc has a purple wire going into the ks then comes back out.. I cut mine and spliced them together and it worked for me, your pretty much acting like the switch was never there. Then I’d go back and find TDC again and make sure your in the right ball park. I’ve even heard of people letting motors sit and a critter will make a nest in the exaust somewhere blocking it completely and causing the pressure to come through the carb... I’d try dumbing it down a little sometimes it’s something very simple that your over looking, good luck!

 

[brunolund]

i agree. i figure it’s something stupid, but i’ve gone over and over it. maybe a little break till tomorrow will allow the mind to reset and i’ll see it right away.

 

[Bszakaly97]

i agree. i figure it’s something stupid, but i’ve gone over and over it. maybe a little break till tomorrow will allow the mind to reset and i’ll see it right away.

Sometimes it is! I would try what I mentioned though... and also one more thing I forgot to mention, check and see if you have power at coil with key on and not just with starter engaged.

 

[brunolund]

will do. i did check coil with key on, it did have 12.6v at the positive.

 

[brunolund]

i figured it out. duh!! guess when i installed distributor 15ish years ago, i pointed the rotor to cylinder 1, and wires it from there. this time, i wired it with #1 wire on the terminal labelled as #1, which is to the rear of the engine. so every time i brought the timing marks together, and the rotor was pointing to #1 wire, i just assumed i was on the compression stroke. stupid mistake, but at least it’s figured out.

now, i know it doesn’t really matter, but which is the proper location? facing the cylinder, or wherever the cap says? pretty sure i’m going to go by the cap and reinstall the distributor, so i don’t run into this again.

 

[Rick Stephens]

Proper way is however the wires end up neat, and of course in the right order.

 

[poconojoe]

Glad you got it figured out!
Happy boating!