Vapor Lock + RPM + Prop selection Questions 2005 Mobuis LSV

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12-25-2013, 03:34 PM
Charl

Vapor Lock + RPM + Prop selection Questions 2005 Mobuis LSV

Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.

2) I cannot seem to get my RPM over 4000 RPM when I am alone on the boat running on full throttle. What RPM should I expect to get and what could the reasons be that I am only achieving 4000 RPM

3) I am considering changing my prop. We are about 1400m (4200ft) above sea level and we use the boat mostly for wakeboarding. What type and size of prop do you suggest.
12-25-2013, 03:42 PM
parrothd

Did you replace the fuel pump? You did everything but that.. :)

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12-25-2013, 09:31 PM
kaneboats

Welcome Chari! We will do our best to help you and anyone else around the world who loves the MOOMBA brand (Supra too!). Can you post the numbers listed on your prop? Sometimes the boat will perform better with a different propeller. Also, do you run ballast? If so, how much do you run? What bags, weights and locations? What types of activities do you and your group do when you go out on your boat?

The more information you give us the more specific the advice we provide will be. Glad to have you aboard!
12-26-2013, 08:38 AM
moombadaze

for the vapor lock, it helps to keep the blower running for a little while after shutting off to help flush out the hot engine air, this can help but is not a fix. think it has to do more with the fuel pump and lines getting so hot.

prop--look the rear of it, there should be some numbers stamped into it, need to know what you running now. but think that motor should rev up to round 5k
12-27-2013, 07:32 PM
DOCDRS

Quote:

Originally Posted by Charl

Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.

Next time out lift the engine hatch after you have run it for 30 mins, then after a 20 min wait , see if it starts and stays running, if it does then you have confirmed vapour lock. Then the best way to solve may be install a high volume, low pressure pump on your line as close to the fuel tank as possible
12-29-2013, 08:45 AM
VA LSV

Quote:

Originally Posted by Charl

Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.

Quick temp fix is keep some bottles of water in the cooler and pour on the fuel pump and lines when you have vapor lock. Permanent fix is add the 2nd fuel pump.

2) I cannot seem to get my RPM over 4000 RPM when I am alone on the boat running on full throttle. What RPM should I expect to get and what could the reasons be that I am only achieving 4000 RPM

Check your linkage at the throttle body. I had to adjust mine so it was full open at full throttle. I think RPM limit is4800.

3) I am considering changing my prop. We are about 1400m (4200ft) above sea level and we use the boat mostly for wakeboarding. What type and size of prop do you suggest.

I have a 14.25 x 14 prop with 1400 lbs of ballast but am only at 1800 ft.
01-09-2014, 12:06 PM
Charl

Hallo Parrothd - I have not replaced the fuel pump as yet. First want to be sure it is the pump. Do you know if a faulty fuel pump could also cause the boat not to exceed 4000 RPM.
01-09-2014, 12:17 PM
Charl

Quote:

Originally Posted by kaneboats

Welcome Chari! We will do our best to help you and anyone else around the world who loves the MOOMBA brand (Supra too!). Can you post the numbers listed on your prop? Sometimes the boat will perform better with a different propeller. Also, do you run ballast? If so, how much do you run? What bags, weights and locations? What types of activities do you and your group do when you go out on your boat?

The more information you give us the more specific the advice we provide will be. Glad to have you aboard!

Hallo kaneboats - Just took the boat out of the water today
I have a MVC HC OJ 13,7 x 17.5
I run the following Ballast -Right back +/- 200kg & -Left Back +/- 200kg & Centre Ski Hatch +/- 200KG
We mostly use the boat for wakeboarding and surfing.
We are +/- 4000 ft above sea level.
As mentioned the boat does not exceed 4000 rpm (but I am not sure if this is a fuel pump or prop or other problem.
What prop would you recommend for my use?
01-09-2014, 12:20 PM
Charl

Quote:

Originally Posted by moombadaze

for the vapor lock, it helps to keep the blower running for a little while after shutting off to help flush out the hot engine air, this can help but is not a fix. think it has to do more with the fuel pump and lines getting so hot.

prop--look the rear of it, there should be some numbers stamped into it, need to know what you running now. but think that motor should rev up to round 5k

Hallo Moombadaze
I have a MVC HC OJ 13,7 x 17.5
I run the following Ballast -Right back +/- 200kg & -Left Back +/- 200kg & Centre Ski Hatch +/- 200KG
We mostly use the boat for wakeboarding and surfing.
We are +/- 4000 ft above sea level.
As mentioned the boat does not exceed 4000 rpm (but I am not sure if this is a fuel pump or prop or other problem.
What prop would you recommend for my use?
01-09-2014, 12:23 PM
Charl

Quote:

Originally Posted by VA LSV

I have a 14.25 x 14 prop with 1400 lbs of ballast but am only at 1800 ft.

Thank you for the reply
I have a 13,7 x 17,5
Any idea what prop I should use for my conditions (I am 4000 ft above sea level_
Also what does the 13,7 and the 17.5 stand for?

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