Twin 717s: right engine won't crank

[splishy]

Hey guys!

I think I finally got my left engine working. The NGK spark plugs were all over the place with their gaps (0.75mm, 2x 0.65mm, and 0.35mm) and super dirty, so I cleaned them and tapped to 0.22" (0.55mm) per manual. I also filled half the tank with 87 (was 91) and bypassed the fuel level fuse so that works now, too!

Anyway, after doing all this my left engine now fires up like a champ every time and sounds a lot deeper/throatier, but my right engine struggled to start (used to fire up no problem) and then finally did after maybe 10x attempts over a 20min period. The engine only got up to about 3k RPM for about 1min and then died (assumption is the fuel line needed to reduce from just 91 to the 50/50 mix). I heard a quiet air puffing sound on the right of the boat right before it died if that helps? (not sure what that was)

Now the engine won't turn at all when attempting to start. Instead it just makes a single click and doesn't turn over. I thought the engine might be flooded so I removed the spark plugs at home and put in an endoscope and it was dry, so nope. I also verified that there's nothing in the prop causing it to lock up.

Any ideas? Thanks!

 

[splishy]

I just tried manually turning the flywheel for the right engine and it won't budge, but the left engine turns easily. Does this mean it's something in the engine upper and/or lower half or could the starter be seized/stuck? I'm not familiar with these 2-stroke starters.

 

[etemplet]

You could have a few problems. Sometimes the starter sticks and remains engaged but won't work. Hopefully this is your problem. Could be something in the jet pump or a problem with the jet pump. Next it could be an issue with the crank, a rod bearing seizing up. Good Luck with it.

 

[splishy]

Thanks for the info! Would I just have to remove the starter if it's stuck engaged? Nothing in the jet pump, I already checked. How would I troubleshoot a rod bearing without opening the bottom case?

You could have a few problems. Sometimes the starter sticks and remains engaged but won't work. Hopefully this is your problem. Could be something in the jet pump or a problem with the jet pump. Next it could be an issue with the crank, a rod bearing seizing up. Good Luck with it.

 

[burtshaver2021]

I’ve had a starter stay engaged before, scared the hell out of me, thought something had went wrong internally. Anyways I was able to free it by gently rocking the pto back and forth. Are you using oil injection or pre mix? You had said your right engine used to fire up no problem, some back story might help, when was the last time you had the boat on the water and what happened during that outing?

 

[splishy]

I’ve had a starter stay engaged before, scared the hell out of me, thought something had went wrong internally. Anyways I was able to free it by gently rocking the pto back and forth. Are you using oil injection or pre mix? You had said your right engine used to fire up no problem, some back story might help, when was the last time you had the boat on the water and what happened during that outing?

A chunk of the history is in my previous threads, but here's a summary:

* Last time out: a week before this happened
* Oil injection (it feels like it goes through ~30% more oil than standard though)
* I previously used 91 octane but this last trip filled the remaining half tank with 87 thinking that was related to the issue (I found out manual states 87)
* I removed the starter and the flywheel still won't budge
* Previously my left engine had all the issues but those appear to be resolved now
* Right engine would start easily prior to this last trip
* Right engine regularly fluctuated between 5k-7.5k RPM when around 60% WOT all season
* Boat only goes up to 5mph or so with 2 people and 1 functional engine at WOT
* Left engine would randomly work (get over 3k RPM) and when both worked, boat could hit 35mph after 1-2min of 15mph @ WOT
* Wear rings appear to be new (within gap specs and per previous owner)
* Left engine had the top end rebuilt last season (per previous owner, confirmed with endoscope)

I installed a locknut on the jet pump bolt but now it won't come off (any tips?) so can't remove the jet pump until that issue is resolved, but I inspected the jet pump and the prop looks good

 

[burtshaver2021]

A chunk of the history is in my previous threads, but here's a summary:

* Last time out: a week before this happened
* Oil injection (it feels like it goes through ~30% more oil than standard though)
* I previously used 91 octane but this last trip filled the remaining half tank with 87 thinking that was related to the issue (I found out manual states 87)
* I removed the starter and the flywheel still won't budge
* Previously my left engine had all the issues but those appear to be resolved now
* Right engine would start easily prior to this last trip
* Right engine regularly fluctuated between 5k-7.5k RPM when around 60% WOT all season
* Boat only goes up to 5mph or so with 2 people and 1 functional engine at WOT
* Left engine would randomly work (get over 3k RPM) and when both worked, boat could hit 35mph after 1-2min of 15mph @ WOT
* Wear rings appear to be new (within gap specs and per previous owner)
* Left engine had the top end rebuilt last season (per previous owner, confirmed with endoscope)

I installed a locknut on the jet pump bolt but now it won't come off (any tips?) so can't remove the jet pump until that issue is resolved, but I inspected the jet pump and the prop looks good

I’m not sure about the bolt on your pump but when you have been trying to rotate the engine by hand, you have the spark plugs out correct? Have you ever ran the boat in the water with only the port engine running? Just wondering if maybe you have flooded the engine with water and now it’s seized up with a little rust. A lot will tell you not to do this but I have removed the engine on a few machines without removing the pump even though I have the alignment tool. If you unbolt the engine mounts? Keep track of how many shims are under each mount and put them back exactly as you found them, you can slide the engine ahead a few inches, just be mindful of the rubber bumper on the driveshaft, that you don’t lose it, and put it back on after If it falls off. If the engine doesn’t rotate by hand then with the plugs out then you know you have some type of internal engine damage.

 

[splishy]

you have the spark plugs out correct?

Correct, and I've even put an endoscope down there to make sure the tops of the pistons aren't flooded at all.

Have you ever ran the boat in the water with only the port engine running?

Yeah, the last time I took it out when the right engine wouldn't start we drifted a bit away from the dock and I had to drive with just the port engine on for about 5 minutes to limp back. Is that a problem/would it cause flooding of the starboard engine?

So I have to unmount the engine in order to drain it out check for it being water locked?

 

[burtshaver2021]

Correct, and I've even put an endoscope down there to make sure the tops of the pistons aren't flooded at all.


Yeah, the last time I took it out when the right engine wouldn't start we drifted a bit away from the dock and I had to drive with just the port engine on for about 5 minutes to limp back. Is that a problem/would it cause flooding of the starboard engine?

So I have to unmount the engine in order to drain it out check for it being water locked?

Yes, without the engine running water could have entered the engine through the exhaust.
No, I only mentioned unbolting the engine so you could slide it ahead off of the driveshaft to eliminate the pump from the equation of you not being able to turn the motor over by hand,

 

[splishy]

Yes, without the engine running water could have entered the engine through the exhaust.
No, I only mentioned unbolting the engine so you could slide it ahead off of the driveshaft to eliminate the pump from the equation of you not being able to turn the motor over by hand,

Gotcha, thanks How would I go about checking for and removing water from the engine if that's the case? And what keeps water out of the exhaust when the boat is stationary vs allowing it in when driving?

 

[burtshaver2021]

Gotcha, thanks How would I go about checking for and removing water from the engine if that's the case? And what keeps water out of the exhaust when the boat is stationary vs allowing it in when driving?

Roughly, When the boat is moving without the engine running the force of the water going into the intake grate and then hitting the prop creates water pressure on the water inllet hose similar to when it’s running but there’s no exhaust pressure to keep the water from entering the engine. Usually when an engine ingests water people will take the spark plugs out and crank the engine over, the water will come out the plug holes. Since you can’t crank it over, you could take the cylinder cover and cylinders off to see if there’s any water in the crankcase. You could then probably soak it up with a folded up shop towel, I’ve done that before when rebuilding a snowmobile engine, I didn’t drain the coolant well enough and some made it’s way to th crankcase when I was taking the cylinders off. Anyways, I was just able to fold up a shop towel to about the size of a ruler and soak it up,

 

[burtshaver2021]

When your driving with only one engine, or towing a Seadoo on the water, the manual shows to pick off the water inlet line

 

[burtshaver2021]

I’m just curious, has the boat sat quite awhile since the last ride in on one engine? The reason I ask is I bought a 98 Challenger that was an almost identical situation, I couldn’t get the starboard engine to turn over with the starter or by hand, I kept putting 2 stroke oil in the cylinders every couple weeks for about 4 months and then this spring it finally let go and cranked over. It had low compression on one cylinder so I ended up taking that engine apart and the low compression was just from a stuck ring due to the rust. There was lots of milky oil in the crankcase and oddly no rust in the crank, just the ring was rusty. Anyways if yours has been sitting long I’m thinking it’s possible that maybe your ring is rusted slightly to the cylinder wall.