Scale won't stay running

[Don Riek]

OK, I am ready for some help.

I have been running a Muck U-4 Scale (Mark & Pak) for two seasons with nothing but "normal" issues here and there. 67 CMB HR, Brown quiet pipe, p-255 SS prop.

In October the boat started quitting mid race. In running down the problem, the boat would run 4 or so laps and then quit for no apparent reason.

I believe I have checked/changed/fixed every possibility known to man. We even put another motor in it at one point. It has boiled down to this: Run boat without the cowling, no problem. Run boat with cowling in place, boat quits after the afforementioned 4 laps.

Now let me say that we have checked for pinched fuel and/or water lines, have enlarged the open area around the driver, took out the driver, added holes in the base of the windshield, took off the windshield, removed foam flotation from underside of cowling, all to no avail. On yeah, we also lowered the nitro % from 60 to 45. Ran the boat again today. 3 3/4 laps with cowling, stopped. restarted without fueling, left cowling off, ran 9 laps and brought it in.

Can anybody shed some light on this????

 

[larcor69]

is there some way your cowl is pinching a line?, maybe something, you dont see??

 

[Ray Sametz]

Don, are you sure your cowling is not in some way affecting the fail safe on your radio???? B)

 

[Don Riek]

is there some way your cowl is pinching a line?, maybe something, you dont see??

We are absolutly sure this is not happening. Lines are very visible from openings in cowling. But yes, we did check this very carefully.

 

[Don Riek]

Don, are you sure your cowling is not in some way affecting the fail safe on your radio???? B)

Ray,

Fail safe is in off mode so I don't think this would be the case. Am I missing something with this?

 

[Ray Sametz]

Don, are you sure your cowling is not in some way affecting the fail safe on your radio???? B)

Ray,

Fail safe is in off mode so I don't think this would be the case. Am I missing something with this?

What radio you using?

 

[Marty Shallenberger]

What does the plug look like when it dies after a few laps ?

Marty Shallenberger

NAMBA National Scale Hydro Chairman

 

[Don Riek]

Don, are you sure your cowling is not in some way affecting the fail safe on your radio???? B)

Ray,

Fail safe is in off mode so I don't think this would be the case. Am I missing something with this?

What radio you using?

Futaba 3PK with 113 FM receiver

 

[Don Riek]

What does the plug look like when it dies after a few laps ?
Marty Shallenberger

NAMBA National Scale Hydro Chairman

Marty,

Plug looks "normal", ie; no discoloration or indication of lean condition. Boat does not seem to be running lean when it quits.

 

[shann harrison]

What does the plug look like when it dies after a few laps ?
Marty Shallenberger

NAMBA National Scale Hydro Chairman

Marty,

Plug looks "normal", ie; no discoloration or indication of lean condition. Boat does not seem to be running lean when it quits.

Water spraying in the carb with cowl on??.Or not enough air choking the engine was my problem I had.The very same problem Darn Scales eh..Shann

 

[brian-lepinski]

I would replace all lines fuel and water. check your water nipples on your motor. check o ring on motor head. check lines in side of fuel tank. Rudder pickup does the boat pee when running. and is uour preasure line clogged on the pipe. just some things I would check then check your bearings and drive line for binding. but it really sounds like there may be a water leak some wear maybe at the srtut that is making a mist in the hull choking the motor. This happened to me when the silicone came undone on my circus. it would run for a lap and quick. once i fixed the silicone it ran great. go figure

 

[Don Riek]

I would replace all lines fuel and water. check your water nipples on your motor. check o ring on motor head. check lines in side of fuel tank. Rudder pickup does the boat pee when running. and is uour preasure line clogged on the pipe. just some things I would check then check your bearings and drive line for binding. but it really sounds like there may be a water leak some wear maybe at the srtut that is making a mist in the hull choking the motor. This happened to me when the silicone came undone on my circus. it would run for a lap and quick. once i fixed the silicone it ran great. go figure

Already replaced all lines, filter, rebuilt tanks, pressure checked all, all lines free and clear, nothing clogged. Bearings were replaced along the line, no apparent binding (seems like this would be a problem with or without cowling) I will check the misting thing, although I can't understand how water would get all the way to the front with the boat running 50+ mph. This is worth a second look. Thank you!

 

[SayMikey]

I would replace all lines fuel and water. check your water nipples on your motor. check o ring on motor head. check lines in side of fuel tank. Rudder pickup does the boat pee when running. and is uour preasure line clogged on the pipe. just some things I would check then check your bearings and drive line for binding. but it really sounds like there may be a water leak some wear maybe at the srtut that is making a mist in the hull choking the motor. This happened to me when the silicone came undone on my circus. it would run for a lap and quick. once i fixed the silicone it ran great. go figure

Already replaced all lines, filter, rebuilt tanks, pressure checked all, all lines free and clear, nothing clogged. Bearings were replaced along the line, no apparent binding (seems like this would be a problem with or without cowling) I will check the misting thing, although I can't understand how water would get all the way to the front with the boat running 50+ mph. This is worth a second look. Thank you!

Id think you could see water coming from the strut ,ive had this happen and it is tough to pinpoint. Also had a blocked fitting on the pipe crap built up and closed it off. I had a 82u55 PT hull that would not run with the cowl on,found only a Macs pipe would work. It would run like heck for a couple laps then lay down and die. Prop it down a bit if you have not piched the sleeve in a while. Hey if it dies after a couple laps bring it to Atlanta maybe i can beat you for a change.............Mike PS i hope you get her fixed

 

[Don Riek]

I would replace all lines fuel and water. check your water nipples on your motor. check o ring on motor head. check lines in side of fuel tank. Rudder pickup does the boat pee when running. and is uour preasure line clogged on the pipe. just some things I would check then check your bearings and drive line for binding. but it really sounds like there may be a water leak some wear maybe at the srtut that is making a mist in the hull choking the motor. This happened to me when the silicone came undone on my circus. it would run for a lap and quick. once i fixed the silicone it ran great. go figure

Already replaced all lines, filter, rebuilt tanks, pressure checked all, all lines free and clear, nothing clogged. Bearings were replaced along the line, no apparent binding (seems like this would be a problem with or without cowling) I will check the misting thing, although I can't understand how water would get all the way to the front with the boat running 50+ mph. This is worth a second look. Thank you!

Id think you could see water coming from the strut ,ive had this happen and it is tough to pinpoint. Also had a blocked fitting on the pipe crap built up and closed it off. I had a 82u55 PT hull that would not run with the cowl on,found only a Macs pipe would work. It would run like heck for a couple laps then lay down and die. Prop it down a bit if you have not piched the sleeve in a while. Hey if it dies after a couple laps bring it to Atlanta maybe i can beat you for a change.............Mike PS i hope you get her fixed

Very funny Mike! Right now everybody is beating me! I did double check the pressure fitting and have pretty much ruled out motor problems since the "backup" motor I put in it (Perry Walters') had the same result.

 

[mark gordon]

Very funny Mike! Right now everybody is beating me! I did double check the pressure fitting and have pretty much ruled out motor problems since the "backup" motor I put in it (Perry Walters') had the same result.

Hi Don I had the same problem with 67 riggger it is water entery into the hull after about 3-4 laps

there is enough water bounce from vibration in the hull it gets sucked down the carby and then its

flame out you can prove it by putting some sponge in the engine bay to soak up the water and I bet

it will keep running for you p.s let me know if it fixes the problem.

regards mark

 

[P THOMAS]

I would replace all lines fuel and water. check your water nipples on your motor. check o ring on motor head. check lines in side of fuel tank. Rudder pickup does the boat pee when running. and is uour preasure line clogged on the pipe. just some things I would check then check your bearings and drive line for binding. but it really sounds like there may be a water leak some wear maybe at the srtut that is making a mist in the hull choking the motor. This happened to me when the silicone came undone on my circus. it would run for a lap and quick. once i fixed the silicone it ran great. go figure

Already replaced all lines, filter, rebuilt tanks, pressure checked all, all lines free and clear, nothing clogged. Bearings were replaced along the line, no apparent binding (seems like this would be a problem with or without cowling) I will check the misting thing, although I can't understand how water would get all the way to the front with the boat running 50+ mph. This is worth a second look. Thank you!

Id think you could see water coming from the strut ,ive had this happen and it is tough to pinpoint. Also had a blocked fitting on the pipe crap built up and closed it off. I had a 82u55 PT hull that would not run with the cowl on,found only a Macs pipe would work. It would run like heck for a couple laps then lay down and die. Prop it down a bit if you have not piched the sleeve in a while. Hey if it dies after a couple laps bring it to Atlanta maybe i can beat you for a change.............Mike PS i hope you get her fixed

Very funny Mike! Right now everybody is beating me! I did double check the pressure fitting and have pretty much ruled out motor problems since the "backup" motor I put in it (Perry Walters') had the same result.

Brian said check for water leak at strut, good idea. Run the boat with out cowl and look for water spray comming out of the strut cut out.. We had a sport 40 do that and the water sprayed inside the cowl right up to the motor with the cowl on. Maybe you could add a floor drain at the back too. Try the old sponge on the floor under the carb trick too.

PHIL T

 

[t_hedlund]

It sounds to me that itis getting too hot.

Have you checked to see if it is getting too hot?

Have you checked the water pick up on the rudder?

 

[DON MAHER]

Where does the water exit? Through the hull or the cowl??? If its through the cowl make sure the discharge is not being "blown" into any opening on the boat. Really sounds like a strut leak

Don

 

[Don Riek]

Guys,

I like the strut leak as the possible problem, however I just looked at the strut entry through the hull and it is virtually sealed with just a very small hole at the trailing edge of the strut. I will seal this off completely and try again.

I had, along the line, thought about water intrusion but could not pinpoint the entry point. The sponge idea is a very clever one and I will try that also because if it works, I can track down the cause from there. Also might have to make the sponge standard equipment!

I have pretty much ruled out overheating with the drop in Nitro %, also there is no indication of lean condition. Water exit is through the hull next to the motor and has not been changed.

Thanks for all of the ideas so far and yes, I will be letting everyone know how this turns out.

 

[Douglas P Shepherd]

Guys,I like the strut leak as the possible problem, however I just looked at the strut entry through the hull and it is virtually sealed with just a very small hole at the trailing edge of the strut. I will seal this off completely and try again.

I had, along the line, thought about water intrusion but could not pinpoint the entry point. The sponge idea is a very clever one and I will try that also because if it works, I can track down the cause from there. Also might have to make the sponge standard equipment!

I have pretty much ruled out overheating with the drop in Nitro %, also there is no indication of lean condition. Water exit is through the hull next to the motor and has not been changed.

Thanks for all of the ideas so far and yes, I will be letting everyone know how this turns out.

What about the exhaust exiting the hull? How does it exit the hull?