only starts with 1 plug out

[josuevos]

Ok my boat only starts with one plug out doesnt matter which plug. Otherwise it will just keep turning indefinitely. The history on my boat. Boat was acting up where it wouldnt start some times. Then i took it out and it ran fine and died in water and got towed in. Rebuilt carburetor a few times and it would fire and run fine for quite a while then went back to start and it wouldnt. Repeated this a few times and realized that water and crud were getting in the carb. So i pumped out all the old gas and redid the carb again. No more water or crap. Changed water separator. Now it wont start at all. So i was checking for spark and getting spark to every plug. I took iut each plug one by one and it would actually start up and run great other than the one missfire. And it runs fine as long as either of the 8 plugs are out. Havent changed the plugs. Put in a new fuel pump which is working fine. Going to put a new starter tomorrow. Battery fully charged. Have 2 new batteries and wouldnt start with either. Help anyone? Boat is 1999 bayliner capri with mercruiser 5.0 thunderbolt ignition alpha 1 gen 2. 2 barrel carb.

 

[NHGuy]

So if the tank is really super clean run some fuel through the line and dump it, not in the carb. You have to get every bit of dirt out. Then once you are confident the gas tank is really perfect recheck the carb, replace the plugs. Should go then. Why the starter, did it get ruined?

 

[josuevos]

Thanks for replying. Yes i got all of the bad gas out. There is no bad gas now. The fuel system is fine. Boat wont start. Only if one spark plug is out. Then it fires up easily. I have changed the oil pressure sender, the oil pressure switch, fuel pump. I saw only a few ppl online reporting this exact incident. The only person that showed the same problem and resolution was a guy with a 2 cylinder ride on lawn mower. Would start only if one of the plugs was out. He replaced the starter and it fixed it. The reason was that if the starter is weak or has issues it may look like its trying to start but not enough to start it. And it wouldve started because with 1 spark plug out it took less power to start due to the lower compression. This is all new to me. I have some experience rebuilding engines. But this i am at a stand still. Ill try a new starter with my thumbs crossed but i am notnso sure its going to work.

 

[josuevos]

I didnt replace the spark plugs. But doesnt make sense why it would only start with 1 plug out. I mean it fires right up and runs minus power to one cylinder

 

[IGeeky1]

I can't help but think maybe you have firing order wrong somehow. Did you have several wires off the plugs at the same time ever? At any rate would be worth a double or triple check.

 

[josuevos]

Ya. I did 1 spark plug at a time believe me. I have the repair manual. But definitely didnt change the spark wires around.

 

[gm280]

:welcome: josuevos to iboats. Great to have you aboard....

Not being there and seeing or testing things myself, it sounds like your starter isn't turning over the engine fast enough with all the plugs installed. Even with a dual battery setup doesn't help because the starter may be on the edge of not spinning fast enough. And then with one plug out it can spin a little faster to start. I would be interested to see how things work once you change the starter. Could be that will fix your problem. Post your results after you get the starter installed. JMHO!

 

[josuevos]

:welcome: josuevos to iboats. Great to have you aboard....

Not being there and seeing or testing things myself, it sounds like your starter isn't turning over the engine fast enough with all the plugs installed. Even with a dual battery setup doesn't help because the starter may be on the edge of not spinning fast enough. And then with one plug out it can spin a little faster to start. I would be interested to see how things work once you change the starter. Could be that will fix your problem. Post your results after you get the starter installed. JMHO!

Thanks for the reply. Im not actually using a dual battery. Im fairly new to working on boats. I had a newer jetski 2012 that ran all horribly one time believe it or not due to a low battery. Sold it cuz I wanted a boat. And now i seriously wish I hadnt. I coulda been on the water!! Kawasaki 1500 3 seater. Really i bought a second battery in case i ran the other out from the stereo. Not that i have a big subwoofer or anything. But shes getting old. Things start to fail by this point. So wish me luck that its the starter. If it is I really think this will be some great info for ppl to down the road try pulling a plug and seeing if that makes it start. And Im not going back to work until trump wins and im back on the water.

 

[stonyloam]

The only thing taking a plug out will do is reduce the work the starter needs to do. I suspect that you have a worn starter that is working too hard to turn the motor and is drawing so much current that you are dropping your battery voltage to the point where your ignition is not functioning. Put a digital voltmeter on the battery to check the voltage when you are cranking to see if there is a significant difference, plug in vs plug out.

 

[NHGuy]

if the timing is too far advanced the starter will be working against the firing cylinders.
If it's too far advanced you could turn the distributor a couple of degrees clockwise to lower the advance a bit. It might then start with all the plugs in place.
If it's Thunderbolt IV set the timing to 8 degrees before top dead center.
If the ignition is Thunderbolt V you will need to put the ignition in base mode before setting the timing, still to 8 degrees I think.
To get to base mode you run a ground to the purple with white stripe wire that will be sitting on top of the intake on the starboard side of the carburetor.
Run the motor til it's warm, set the idle to 675 and the timing to 8 degrees. Then shut off the engine remove the jumper and restart in normal mode.

 

[josuevos]

Ya i dont know how to do timing. I dont have a timing gun. Never messed with that. So the starter didnt fix anything. The old one was tired for sure this one has that new car sound. So the new carburetor should be here hopefully this week. Yup. I duno what else to do. Cant get a mechanic for 2 weeks and theyll probably be super to expensive. So im changing parts. It doesnt make sense thats for sure unless the engine is fried. I didnt do a compression check or any tests on the coil. But like i said i got spark and itll fire up with a plug pulled out. Im about as frustrated as hell. Ill try to do a compression check when i can.

 

[josuevos]

The reason im replacing the carb is i think its not getting air. Pulling the plug could be allowing air in. I dont understand carburetors very much. I was also thinking maybe there is somethi g wrong with the exhaust side. Because maybe theres water in there or something? I do t know...

 

[josuevos]

if the timing is too far advanced the starter will be working against the firing cylinders.
If it's too far advanced you could turn the distributor a couple of degrees clockwise to lower the advance a bit. It might then start with all the plugs in place.
If it's Thunderbolt IV set the timing to 8 degrees before top dead center.
If the ignition is Thunderbolt V you will need to put the ignition in base mode before setting the timing, still to 8 degrees I think.
To get to base mode you run a ground to the purple with white stripe wire that will be sitting on top of the intake on the starboard side of the carburetor.
Run the motor til it's warm, set the idle to 675 and the timing to 8 degrees. Then shut off the engine remove the jumper and restart in normal mode.

Are you saying to rearrange the timing chain? I never touched that. To my understanding when it comes to timing chains there should only be one right way to install them.

 

[Newbie@boats]

The reason im replacing the carb is i think its not getting air. Pulling the plug could be allowing air in. I dont understand carburetors very much. I was also thinking maybe there is somethi g wrong with the exhaust side. Because maybe theres water in there or something? I do t know...

Throwing random parts at it will get VERY expensive VERY quick, take the advice and figure out timing issues first, if not find someone who can help you.

 

[NHGuy]

No need to mess with the chain. Just check the timing at cylinder #1 via the distributor with a light.