Engine missing

[WilCo]

2013 AR190
Impeller replaced in 2017 shortly after purchasing.
Engine replaced 2018 (timing chain break) with new engine from Yamaha
Boat has been run pretty consistently 1-2 times/week last 2 months or so (thank you Texas weather).
~1 month ago, started noticing that engine was missing a bit around 6500 rpm, which happens to be about the throttle that gives the best wakeboard and kneeboard towing speed for my kids -- so it's used regularly.
Even though I replace the spark plugs annually, I did them again just to be sure (see lengthy other thread about incorrectly gapped plugs, stuck plugs, etc which was reviewed by a mechanic)

Tested after spark plug change and had same engine miss around 6500 rpm as before.
Air filter is clean - no evidence of oil on it so don't think I have overfilled.

Added 2 cans of SeaFoam Marine Pro to my 3/4 full of fuel boat before we got on the water yesterday. Ran for a few hours without any noticeable issue. Was starting to think perhaps the SeaFoam and fresh plugs had worked together to clear any issue. Then engine started bogging down pretty bad while towing the tube. Pulled the tube in and ran WOT for a bit (while headed towards the dock just in case) to see how it sounded. It didn't seem to get much better (at times would struggle a bit and other times sounded good).

Finally decided to put it back on the trailer. Made a video at WOT while focused on the tach. It stayed at 7000 rpm for the first 6 seconds of the video before shooting up to about 7600 for the final 5 seconds of the video. Top speed was 24 mph per the digital speedometer, much lower than normal.

Pulled the impeller and there is some definite leading edge damage and wear ring damage that I need to take care of, but I don't think it fully explains the engine fluctuation. Fellow member @tdonoughue has offered to hook it up to the YDS so will do that when our schedules mesh, but open to any other ideas you may have as well. What else should I check?

 

[tdonoughue]

So my thought is that this is electrical. Seems to be one of those intermittent problems. I thought at first it might be something in the impeller maybe making it feel like an engine issue, but the video of it at WOT makes me think not.

Was going to see what YDS shows, but I thought it would be a good idea to get some of you experts in on the program here...

 

[WREKS]

@WilCo What worries me is that you had such a terrible time getting the 1 and 2 plugs out. When the new timing chain was put in, was the valve clearance checked and adjusted? Also, was the new timing chain properly aligned with the camshafts? You probably were not there when the work was done so you cannot answer those questions, but I would want those questions answered. Can you elaborate on what took place with the replacing of the timing chain?

 

[WilCo]

Entir

@WilCo What worries me is that you had such a terrible time getting the 1 and 2 plugs out. When the new timing chain was put in, was the valve clearance checked and adjusted? Also, was the new timing chain properly aligned with the camshafts? You probably were not there when the work was done so you cannot answer those questions, but I would want those questions answered. Can you elaborate on what took place with the replacing of the timing chain?

Entire engine was replaced, including timing chain.

 

[WREKS]

By entire engine, do you mean new cylinder head, new valves, new pistons, camshafts, block, etc? I did not think one could buy an entire engine.

 

[Cobra Jet Steering LLC]

spray all your electrical connections with silicon spray and see if it solves the problem I agree that it sounds like an electrical issue check the injector connections and the ground wires to the engine also. and check the oil level , make sure it does not smell like gas and it is not overfilled.

 

[WilCo]

By entire engine, do you mean new cylinder head, new valves, new pistons, camshafts, block, etc? I did not think one could buy an entire engine.

I will double check my notes, but boat was out of service for about 2 months while Yamaha corporate shipped everything to the dealer. If I had paid for it, I was told it would’ve cost over 20K. I was told new engine.

 

[WilCo]

I will double check my notes, but boat was out of service for about 3 months while Yamaha corporate shipped everything to the dealer. If I had paid for it, I was told it would’ve cost over 20K. I was told new engine.

Notes from 2018...august 5 failure occurred. everything was ordered Aug 27. Sep 8 all parts in except 2 gaskets. Sep 18 valve cover with tensioner is backordered, but everything else was bak in the boat. Oct 5, they completed engine swap. There was a comment about mixing and matching some parts from my engine to the new one, but I did not get a list of what was reused and what was new. They showed me the old engine sitting to the side when I picked up the boat and it would fill a pretty large crate so quite a few things were replaced. As you said, I was not there and they did not give me any paperwork so I can't say definitively what was and wasn't replaced.

EDITED TO ADD: Corporate ordered the engine parts and they advised the dealer to order everything else that would be needed. So perhaps corporate has the ability to get an engine in versus consumers. I recall the dealer telling me the engine had come in from Japan.

 

[tdonoughue]

But the boat has been running fine since that time, right?

Were the valves off or the chain off, it would always be off. You would not be running along at WOT at 7k rpm and have it suddenly jump up to 7800. Would it?

That said, I cringe when I think that they used parts and recomposed your engine... But I still think it is electrical.

 

[WilCo]

Correct. I've run 2 years on the new engine - or some combination of new and old parts. Boat had only about 85 hours on the 1st engine. Hour meter now shows 137.1 so I have about 52 hours on the new engine. I burned through only about 7 gallons of gas yesterday with the SeaFoam in it so I guess there's a chance that I need to burn some more if there is a fuel injector clog...

 

[marcham]

Are you able to measure the voltage while the engine is running? Symptoms are similar to a stator or regulator failure on a motorcycle.

 

[WREKS]

So it was running fine for a while when you first got it back? It should have had a top end at about 8K. Why did you first change the plugs, just to do maintenance or were you having a problem? You said in Post#1 of Thread "Spark Plugs Binding," "Engine has been missing around 6500 rpm pretty consistently, so I decided to change the spark plugs even though they aren’t that old. I previously went with NGK LFR6 (not A) and gapped them myself. " So did you put the NGK LFR6 in the new engine and then change them again, or were the NGK LFR6 plugs what you used to use on the old motor?

 

[WilCo]

Are you able to measure the voltage while the engine is running? Symptoms are similar to a stator or regulator failure on a motorcycle.

Pump is pulled at the moment. But yes, I can do that. Digital gauge reports voltage and I have a multimeter both so will do one or both methods.

 

[WREKS]

But the boat has been running fine since that time, right?

Were the valves off or the chain off, it would always be off. You would not be running along at WOT at 7k rpm and have it suddenly jump up to 7800. Would it?

That said, I cringe when I think that they used parts and recomposed your engine... But I still think it is electrical.

Do you think the old pistons, rods, and bearings may have been installed? If so, they had to get battered by the chain failure.

 

[WilCo]

So it was running fine for a while when you first got it back? It should have had a top end at about 8K. Why did you first change the plugs, just to do maintenance or were you having a problem? You said in Post#1 of Thread "Spark Plugs Binding," "Engine has been missing around 6500 rpm pretty consistently, so I decided to change the spark plugs even though they aren’t that old. I previously went with NGK LFR6 (not A) and gapped them myself. " So did you put the NGK LFR6 in the new engine and then change them again, or were the NGK LFR6 plugs what you used to use on the old motor?

Yes, I put at least 45 hours on the new engine without issue. Dealer put new plugs in when they replaced the engine (2018). I replaced them sometime (likely Feb 2019, but I didn’t log that maintenance item unfortunately-that’s when 8 did that oil change though so prett6 sure I did plugs then also) with the LFR6 and did not have engine issues until recently.

I had mechanic install the LFR6A plugs this month without a consistent improvement. Cheap test without improvement, but likely saved other problems down the line given the 2019/2020 plugs were hard to get out.

 

[WilCo]

Do you think the old pistons, rods, and bearings may have been installed? If so, they had to get battered by the chain failure.

I will call tomorrow and try to get the history from the dealer. They should have given paperwork but didn’t.

 

[Scottintexas]

What About water in the fuel tank? When scubaref had his issue it was very intermittent with rpms

 

[WREKS]

Hopefully, it is electrical or fuel related. Prior to YDS diagnosis, are you able to start testing any of the electrical components related to the problem such as ignition coils? The service manual gives good instruction on doing that.

 

[WilCo]

Do you think the old pistons, rods, and bearings may have been installed? If so, they had to get battered by the chain failure.

Per the invoice, Yamaha Corporate sent the cylinder block and head. The dealership shows on the invoice that they replaced a ton of gaskets, transfer shaft, coupling flange, o-ring, rotor assembly, woodruff key, breather assembly, oil filter, spark plugs, oil pump assembly, and probably a few more things I missed. All of this was at 82.1 engine hours (I was off by 3 hours in what I posted above).

So my assumption is that the cylinder block included new pistons, rods, and bearings. I'm trying to reach corporate so I can get that answered definitively.

 

[WREKS]

Per the invoice, Yamaha Corporate sent the cylinder block and head. The dealership shows on the invoice that they replaced a ton of gaskets, transfer shaft, coupling flange, o-ring, rotor assembly, woodruff key, breather assembly, oil filter, spark plugs, oil pump assembly, and probably a few more things I missed. All of this was at 82.1 engine hours (I was off by 3 hours in what I posted above).

So my assumption is that the cylinder block included new pistons, rods, and bearings. I'm trying to reach corporate so I can get that answered definitively.

This may or may not be related to your present problem, but according to the 1.8 Timing Failure Thread, these engines suffer catastrophic failure when the timing chain breaks. Looks like they just replaced the 4/3 chain with another 4/3 chain and used the original pistons, valves, rods, bearings.