Intermittent start issues on single engine only

[FLJetBoater]

These spark plugs, unlike car/truck plugs, usually operate for long periods of time at higher RPM's so the beating they take is crazy.
Not to go in a different direction but check to make sure the wiring harness on the plug coils isn't lose or anything like that. Heck, I would also check the Fuel injector harness connectors. While changing out to new plugs those could have been moved and that "fixed" your starting issues. Just something else to look at because I don't think 1 bad plug will prevent your engine from starting.

Thanks I will take a look at those later on today.

 

[Ronnie]

Another part to consider is the rectifier. It looks like a small radiator, is smaller than a deck of cards and is usually mounted near the top of the engine. I had one go bad on a 2006 Waverunner with an mr1 motor. It caused intermittent starting problems. They cost under $50 at the time over 10 years ago. Assuming you have a twin engine boat just swap their rectifiers to check if one is bad. It’s a 15 minute job max.

 

[FLJetBoater]

Another part to consider is the rectifier. It looks like a small radiator, is smaller than a deck of cards and is usually mounted near the top of the engine. I had one go bad on a 2006 Waverunner with an mr1 motor. It caused intermittent starting problems. They cost under $50 at the time over 10 years ago. Assuming you have a twin engine boat just swap their rectifiers to check if one is bad. It’s a 15 minute job max.

If the starting problems return I will give that a try...

 

[Ronnie]

If the starting problems return I will give that a try...

It wasn’t just starting problems, sometimes the engine started fine and would run for a while before just dying without warning. The last time I was over 3 miles from the ramp and had to be towed back because I could not restart the engine, just crank it.

 

[Cobra Jet Steering LLC]

A few things come to mind bad fuel or bad injector or bad coil connection I never wash down my engines with a hose and I run in salt water I coat them with white lithium grease and I put dielectric grease on the coli boots from day 1,

 

[anmut]

They are absolutely the correct plug. I know because when I go to get them from autozone they always tell me that they have about 1500 in stock lol. The autozone I go to supplies SBT.
And I always double check the boxes for the 6668 code

Usually the one's in stock at the Autozones are the incorrect plugs. My 1.8 takes the NGK LFR6A 6668 plugs, which is unavailable at the local auto parts stores. Check your manual.

 

[FLJetBoater]

Usually the one's in stock at the Autozones are the incorrect plugs. My 1.8 takes the NGK LFR6A 6668 plugs, which is unavailable at the local auto parts stores. Check your manual.

Those are exactly the ones I use. Autozone Clearwater stocks over 1000 of these plugs

 

[FLJetBoater]

It wasn’t just starting problems, sometimes the engine started fine and would run for a while before just dying without warning. The last time I was over 3 miles from the ramp and had to be towed back because I could not restart the engine, just crank it.

I haven’t had that happen. It was at the end of a day, and all of a sudden wouldn’t start. And changing the plugs fixed it but I do get that it could have been something else I touched while changing the plugs

 

[FLJetBoater]

Those are exactly the ones I use. Autozone Clearwater stocks over 1000 of these plugs

I’m sorry not autozone. Advance auto parts…they’re right next door to each other.

 

[FLJetBoater]

A few things come to mind bad fuel or bad injector or bad coil connection I never wash down my engines with a hose and I run in salt water I coat them with white lithium grease and I put dielectric grease on the coli boots from day 1,

Bad fuel would affect both engines though no? I could see bad coil connection but wouldn’t it have to have been more than 1? 1 bad coil or plug shouldn’t stop the engine from starting should it?

 

[anmut]

Those are exactly the ones I use. Autozone Clearwater stocks over 1000 of these plugs

You have an awesome Autozone then!

 

[Ronnie]

Misc pics of my coils and plug failure. Again the engine still ran for the entire weekend, it just ran rough, started hard and sometimes died at idle.

@FLJetBoater , changing the spark plugs may not have solved the problem, the engine starting after the plugs were changed may have been coincidental to the rectifier working properly after the plugs were replaced. If the rectifier fails it may be without (further) warning. With my luck it’s at the start of the day, right after I’ve driven hours to the lake with a boat full of guests.

 

[FLJetBoater]

Misc pics of my coils and plug failure. Again the engine still ran for the entire weekend, it just ran rough, started hard and sometimes died at idle.

@FLJetBoater , changing the spark plugs may not have solved the problem, the engine starting after the plugs were changed may have been coincidental to the rectifier working properly after the plugs were replaced. If the rectifier fails it may be without (further) warning. With my luck it’s at the start of the day, right after I’ve driven hours to the lake with a boat full of guests.

I'm not having any of those symptoms though. Started it up a half dozen times today at random and it's been fine every time. Will give it a good run out tomorrow and see how it goes.

 

[FLJetBoater]

Misc pics of my coils and plug failure. Again the engine still ran for the entire weekend, it just ran rough, started hard and sometimes died at idle.

@FLJetBoater , changing the spark plugs may not have solved the problem, the engine starting after the plugs were changed may have been coincidental to the rectifier working properly after the plugs were replaced. If the rectifier fails it may be without (further) warning. With my luck it’s at the start of the day, right after I’ve driven hours to the lake with a boat full of guests.

So, I had the engine do this again while I was in Bimini last week. Only once, on the 4th day. We had minimal usage on it on the 3rd day. On day 4 we loaded up (started fine at the dock) and head over to radio beach. Spent several hours there and as we went to move up the coast a bit the engine wouldn't start. Cranks for a second then just stops. Sounds like it wants to start but doesn't. After about 15-20 tries to start it FINALLY started and was fine the rest of the trip.

Any thoughts on what could cause something like this or what next troubleshooting steps could be if it happens again? Or things I could do now that would give clues in the future (swapping coil packs?) I imagine it won't be possible to diagnose while it's starting fine.

edit: additional info....

It never cuts out while running
Runs up to 8000 or so rpm no problem. Don't very often push past that

 

[suke]

So, I had the engine do this again while I was in Bimini last week. Only once, on the 4th day. We had minimal usage on it on the 3rd day. On day 4 we loaded up (started fine at the dock) and head over to radio beach. Spent several hours there and as we went to move up the coast a bit the engine wouldn't start. Cranks for a second then just stops. Sounds like it wants to start but doesn't. After about 15-20 tries to start it FINALLY started and was fine the rest of the trip.

Any thoughts on what could cause something like this or what next troubleshooting steps could be if it happens again? Or things I could do now that would give clues in the future (swapping coil packs?) I imagine it won't be possible to diagnose while it's starting fine.

edit: additional info....

It never cuts out while running
Runs up to 8000 or so rpm no problem. Don't very often push past that

Mine does this when it's hot. I gapped my plugs REALLY close to the lower limit to get a hotter spark. It's almost like old school vapor lock. Mine would still do it from time to time, but when it does I'll let the other motor run for a minute, then try again. It normally starts up fine after that. I thought about switching to the iridium plugs to see if that would help. Normally it's when the air temp is hot and water temp is also hot(i.e both above 90*).

 

[FLJetBoater]

Mine does this when it's hot. I gapped my plugs REALLY close to the lower limit to get a hotter spark. It's almost like old school vapor lock. Mine would still do it from time to time, but when it does I'll let the other motor run for a minute, then try again. It normally starts up fine after that. I thought about switching to the iridium plugs to see if that would help. Normally it's when the air temp is hot and water temp is also hot(i.e both above 90*).

Interesting...that seems to be what's going on with mine. It's never happened (so far) when the engine is cool - always after it's been run for a while. I didn't change the gap on the plugs but I did swap them the first time this happened and it fired right up after that. This time I just stuck with cranking it and eventually it fired. It's an E series with push buttons so you can't hold the key like you would it just stops cranking after a few seconds.

 

[suke]

Interesting...that seems to be what's going on with mine. It's never happened (so far) when the engine is cool - always after it's been run for a while. I didn't change the gap on the plugs but I did swap them the first time this happened and it fired right up after that. This time I just stuck with cranking it and eventually it fired. It's an E series with push buttons so you can't hold the key like you would it just stops cranking after a few seconds.

Funny enough mine did it today after idling a long time getting to the dock. After we ran it clear across the lake. So it was good and hot. Putting it on the trailer with one motor was less than graceful, but it worked. Fired right up once out of the water. I generally will just crank until it starts. It's under warranty if I burn up a starter. It's also intermittent, so taking it to the dealer is a waste of time.

 

[Kane]

Curious if you ever figured this issue out?

 

[suke]

Funny enough mine did it today after idling a long time getting to the dock. After we ran it clear across the lake. So it was good and hot. Putting it on the trailer with one motor was less than graceful, but it worked. Fired right up once out of the water. I generally will just crank until it starts. It's under warranty if I burn up a starter. It's also intermittent, so taking it to the dealer is a waste of time.

Fyi this latest round was cured with new plugs, again. Took it out last weekend and abused it. Surfed for HOURS, floated for a bit, drove to get lunch and gas, surfed some more, floated some more, and then wakeboarding until dark a few days in a row. No issue starting. So for me once it does it again I'll change the plugs. Haha!