RPM Jumping, Prop Slipping?

[jtight7]

Good Morning Crew,

Over the weekend my 2001 23LSV Sunscape started RPM bouncing intermittently. It seems to be random but more prominent when pulling a boarder. I checked to make sure that all of the fluid levels in the transmission and V-drive are good. I also put it in neutral and was able to rev the motor without re-occurrence of the issue so this leads me to believe that it is something with the drive train i.e. transmission, V-drive, or prop slipping on the drive shaft. Has anyone experienced this before and found a solution? I want to know if I am going down the right path or if I am completely missing something? 

[Michigan boarder]

Have you replaced your ignition parts regularly?  It could be that you are misfiring because of a bad plug, or wire, or cap/rotor corroded and when it fires the RPM's increase and when it doesn't they drop.

[jtight7]

Yes, I replaced the cap, rotor, plugs, and plug wires this year. I was going to make sure that everything I changed was all tightened up tomorrow evening but I think all of that is working properly because I can place it in neutral and rev the motor to 3000 RPMs+

[Michigan boarder]

3 minutes ago, jtight7 said:

Yes, I replaced the cap, rotor, plugs, and plug wires this year. I was going to make sure that everything I changed was all tightened up tomorrow evening but I think all of that is working properly because I can place it in neutral and rev the motor to 3000 RPMs+

In neutral that engine can rev even if it is on 6 cylinders, it's when it is under load that you'll feel the impact.  I'd double check your connections tomorrow evening.

On the prop slipping, that is not possible, it is a keyed shaft.  If that has failed it would not be intermittent, you simply would have no propulsion.

I'm not savvy on the v-drive or tranny, can't help there.

[jtight7]

8 minutes ago, Michigan boarder said:

In neutral that engine can rev even if it is on 6 cylinders, it's when it is under load that you'll feel the impact.  I'd double check your connections tomorrow evening.

On the prop slipping, that is not possible, it is a keyed shaft.  If that has failed it would not be intermittent, you simply would have no propulsion.

I'm not savvy on the v-drive or tranny, can't help there.

Thank you for the info, I did not know that! I will check it out tomorrow and update

[APoko]

The trans could be slipping...  These types of transmissions use a planetary gear-set and a set of wet-disc clutch discs similar to an automotive automatic trans which could be worn out. 

[minnmarker]

Have you checked the trans fluid level?  If too low it could slip and you want to fill it up ASAP to prevent (additional) damage.  Also, if it was low it would be a good idea to find out why.

[jwl019]

Is it at certain rpm ranges when pulling?  Check your fuel pressure by using a pressure gauge hooked up to the schrader valve next time you go out, here is what it should read - https://www.bakesonline.com/images/MediaLibrary/Indmar_96-06FuelpsiRef.pdf

 

If it is at certain rpm ranges, it could be the fuel hammer issue and there are several threads on this if you run a search but here is one example:

 

[jtight7]

19 hours ago, minnmarker said:

Have you checked the trans fluid level?  If too low it could slip and you want to fill it up ASAP to prevent (additional) damage.  Also, if it was low it would be a good idea to find out why.

The trans level is good and I dont see any leakage around the transmission cooler or transmission case. There is also no transmission fluid in the bottom of the hull. 

The boat only has a total of 298 hours on it. I think that is relatively low.

19 hours ago, jwl019 said:

Is it at certain rpm ranges when pulling?  Check your fuel pressure by using a pressure gauge hooked up to the schrader valve next time you go out, here is what it should read - https://www.bakesonline.com/images/MediaLibrary/Indmar_96-06FuelpsiRef.pdf

 

If it is at certain rpm ranges, it could be the fuel hammer issue and there are several threads on this if you run a search but here is one example:

 

I tested it at all different RPM values and had the same result. It seem more prominent at 2000RPM or higher but it was not consistent or indicative of a pattern. For example, I would cruise at 2000 RPMs for 3-4 min then the RPMS would bounce around but the next time I would be able to go for 10 min at 2000 RPMs with no issue.

I am heading out to lake tonight to troubleshoot, I will take a pressure gauge with me, thank you for the info.

[minnmarker]

I guess keep it simple before replacing parts.  Is the throttle linkage tight?  Disconnect the Perfect Pass if you have one.  Make sure all the plug wires are on correctly and tight at the cap and the plugs.  Fuel pump hot or whining?

It does sound electrical, and the fact that you just replaced the ignition parts points to them being the problem.  Look first where the last changes were made.

[Sixball]

So can you hear the RPM increasing or dropping?  Could it just be the tach? Have a look at the under water gear lose fin, strut. If you are getting air at the prop you could be getting prop cavitation.  If you have sheered the prop key the prop sometimes does not just spin. Sometimes you will have enough interference with parts of the key to bind and slip.  

[jtight7]

I had some bad weather this weekend and was not able to get out on the water to do any further testing but the fuel pressure at idle looked good and I terminated all of the spark plug wires again. Tomorrow evening is supposed to have better weather so I plan to head out and check the above mentioned items. 

I have the old distributor and rotor and spark plug cables so I may switch them back just to see if that makes a difference. 

On 6/2/2016 at 9:16 AM, minnmarker said:

I guess keep it simple before replacing parts.  Is the throttle linkage tight?  Disconnect the Perfect Pass if you have one.  Make sure all the plug wires are on correctly and tight at the cap and the plugs.  Fuel pump hot or whining?

It does sound electrical, and the fact that you just replaced the ignition parts points to them being the problem.  Look first where the last changes were made.

I did not check the fuel pump itself but I did not notice a whining or if it was hot. I will check the next time I head out there

[formulaben]

Without the benefit of hearing/feeling the RPM fluctuations I would follow Sixball's advice first and check (better yet remove, inspect and re-install) the prop before going down the electronics/fuel route.  Should only take a few minutes...eliminate the easy/obvious first.

[jtight7]

On 6/2/2016 at 10:40 AM, Sixball said:

So can you hear the RPM increasing or dropping?  Could it just be the tach? Have a look at the under water gear lose fin, strut. If you are getting air at the prop you could be getting prop cavitation.  If you have sheered the prop key the prop sometimes does not just spin. Sometimes you will have enough interference with parts of the key to bind and slip.  

Yes, I can hear and feel the RPM's drop. It sounds like the motor wants to die if I stay on the throttle once the RPM's start bouncing.

[formulaben]

...but no misfire?  Clogged fuel filter?  Are you POSITIVE the perfect pass is OFF? when troubleshooting?  (I assume it is ON when pulling a boarder.)

Edited June 6, 2016 by formulaben

[jtight7]

1 hour ago, formulaben said:

...but no misfire?  Clogged fuel filter?  Are you POSITIVE the perfect pass is OFF? when troubleshooting?  (I assume it is ON when pulling a boarder.)

I ran it with the perfect pass on and off. The issue occurred in both instances. I am not sure about the fuel filter, it is less than a year old so I would think it would still be fine but I will check when I go up

[jtight7]

Alright, I managed to make it out on the water last night and was able to check a few more things. I drove around for about an hour, maybe a little longer with no issue. I thought that the issue was resolved BUT I was wrong. The issue seems to occur when I get up to speed slow down and then speed back up. When I noticed it last night I was going 27 mph then I slowed down to about 19 mph then applied more throttle to get back up to 27 mph and that is when it happened again. I repeated this at low rpm's and at higher rpm's and got the same result. 

Things I tested last night:

I test the fuel pressure again and it was within the range

Fuel pump was not hot or whining 

Throttle Linkage was tight

Transmission level was good. 

Prop looked secure on the shaft. I was not able to inspect closely due to the lift that it is on. I may pull the boat out this weekend to take a better look.

Due to a setting sun I was not able to replace the old distributor cap and rotor with the old one. However, my thoughts are leaning more and more towards the fuel system. Thoughts and/or suggestions?

 

[JasonK]

Can you get it to happen when the boat is cold? Try to make it occur when you first go out. Could be a coil that's failing when hot.

Anyone have TPS (throttle position sensor) problems? Had to replace one on a car before.

[MadMan]

21 minutes ago, jtight7 said:

I test the fuel pressure again and it was within the range

Was this while the problem was actually occurring?

[jtight7]

No it was at idle. It was only myself on the boat so I was not able to run back and look while it was happening

[jtight7]

3 hours ago, JasonK said:

Can you get it to happen when the boat is cold? Try to make it occur when you first go out. Could be a coil that's failing when hot.

Anyone have TPS (throttle position sensor) problems? Had to replace one on a car before.

I have only noticed it when it is hot. I will try to replicate when its cold next time i am out.

[hgh3g]

I will be very curious to hear what you find.

I am encountering a similar issue with 07' Response LXI. Fault shows cylinder 1 misfire. I just replaced the cap, rotor, plugs, and wires. I suppose the next step is the coil. Tonight, I took 3 slalom sets and 2 wake board sets, and was then cruising around when the display flashed service needed and drop down to 2,000 rpm. After the service needed message there was a noticeable miss. The first time I had this fault, as after being on the water for about 30 minutes. It seems to only occur when it gets hot. 

[jtight7]

I finally had some good weather this weekend and the time to investigate my issues a little further. I went through and checked all of my connections again and pulled each spark plug to make sure that it was dry. My issue is very symptomatic of a misfire but I was able to rule that out and move from the ignition system to the fuel system. Friday night it took about an hour for the problem to start occurring again and Saturday it started right away. It wasnt until I was in the middle of the lake and the boat died that I finally figured out the problem, the fuel pump. It finally died. When I had checked the fuel pressure previously the pump was running ok and failing intermittently so I was not able to see when the pressure was dropping. Luckily while I was being towed back to my slip I had my multimeter and was able to confirm that I was getting voltage to the pump (the fuses were all good up to the pump) and the pump wasnt running, I also was getting 0psi on the schrader valve. 

For my 2001 Sunscape 23LSV, I ordered http://www.bakesonline.com/detail.aspx?ID=1241 last night. When I get it installed and back in the water I will update this thread again. 

I'd like to take a second and say thank you to the family that took an hour and a half out of their beautiful Saturday to tow me back to my slip and refused to accept any form of payment. The only thing that they asked was that if I see someone stranded to take the time and tow them back because we all have been there and know the feeling of having a bad day. Pay it forward when you can! It gives me hope that there are still kind and generous people out there!

[williemon]

I just had to replace mine due to misfire like symptoms under load. I had a couple clogged injectors as well. Mine did squeal though. I squealed as well when i paid for the pump. 

[jtight7]

18 minutes ago, williemon said:

I just had to replace mine due to misfire like symptoms under load. I had a couple clogged injectors as well. Mine did squeal though. I squealed as well when i paid for the pump. 

Yeah, the pump isnt cheap. Did you replace your injectors? If so, how was that process? I have a feeling that if the pump doesnt resolve  my issues that will be the next thing to replace.