Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: Martin [Admin] on April 20, 2009, 03:15:41 PM

Title: Irvine 72 help?
Post by: Martin [Admin] on April 20, 2009, 03:15:41 PM
Via email to Mayhem...

I need some advice on engine fuel and engine performance, I have been running nitro cars and a raptor helicopter and been using a general fuel, unsure what fuel it is now as the label has come off, however i have now acquired a boat from a friend at work and this weekend managed to get it running on the fuel i had however not really sure if it liked it, it started and run ok but every time i put the throttle on it stalled out. The engine is a Irvine 72 and it requires a 24 volt starter to get it turning over, the boat has a speed of 60 mph and is a class racing boat so wonder if its the fuel i am using which may cause the way the engine is running.

One thing i noticed is that there appears to be air in the fuel line and if the engine stalls you can see the air traveling back up the fuel line  from the motor, just prior to the engine stopping in goes from a nice tick over to high rev and the stops which i think that means running lean or fuel starvation.

The boat is fitted with a main fuel tank and then fuel is drawn from a small header tank but when i filled with fuel the header tank would not retain fuel and went back into the main tank with this in mind i took out the header tank and did not seem to make much difference.

Any suggestions on fuel and engine settings to try and get this sorted
Title: Re: Irvine 72 help?
Post by: andyn on April 20, 2009, 04:01:05 PM
It sounds like there isn't enough fuel getting to the engine, with it going lean. Try richening about quarter of a turn per time. If this doesn't work, there is probably a blockage in the fuel line somewhere. Does this person use a clunk type tank? The filter in the clunk may have something stuck in it. To take the clunk apart, it simply unscrews, use an old toothbrush to clean it. It is best to use a fuel filter in line with your filler when filling the fuel tank, not just relying on the filter in the clunk. Try also taking the header out of the system.

The other possible cause is that the fuel tank / header is too low down in the boat. Is the bung in the fuel tank in line with the crankshaft of the engine?

Pics would be best if possible.
Title: Re: Irvine 72 help?
Post by: paw249 on April 20, 2009, 04:47:40 PM
Hi,if you try starting the engine with the glow plug slackened off you will probably be able to start it on a 12v battery.having to slacken the plug and then tightening again when runnig is quite normal on a 10cc plus marine engine.Sounds like you need to richen the main needle to stop the stalling problem.If you remember on your helis the the secondry tank is there to help with fuel frothing problems and to give a constant head of fuel to the engine.Real bad frothing and bubbling could be a vibration problem from bad shaft/coupling alighnment or engine internal problem or maybe just a fuel line airleak.Dont forget you need a pressurised system with a header tank to work properley.Good luck
Title: Re: Irvine 72 help?
Post by: andyn on April 20, 2009, 04:59:01 PM
Try richening first. You should only ever need to slacken the plug if the engine is not turning over due to flooding etc. Most large engines need more oomph to turn them over.
Title: Re: Irvine 72 help?
Post by: omra85 on April 20, 2009, 07:43:39 PM
Sounds stupid, I know, but there is an air vent into your fuel tank, isn't there? Unless it's a pressurised system (from the exhaust) in which case, are you getting pressure?
Sucking air from the carb is a sign that there is a vacuum somewhere in the system.

Title: Re: Irvine 72 help?
Post by: AndyB on April 21, 2009, 07:56:03 PM
Thanks for all the answers gave me so far but just need a bit more advice, I am still trying to set up this engine and need advice on the settings, on the side of the engine is a grooved nut  and then down the middle of this is a black pin. Can anyone tell me where is a good place to set these for the first time and which one is the idle /high speed setting. Not really had as much problem as i have with this engine so advice on this would be great
Title: Re: Irvine 72 help?
Post by: andyn on April 21, 2009, 09:16:55 PM
It's hard to tell for a specific engine, but try closing the needle completely, then opening it three full revolutions, then go from there.

The aero version of the Irvine 72 (mark 2's are red)
Title: Re: Irvine 72 help?
Post by: AndyB on April 22, 2009, 09:12:23 PM
thats the one i have but water cooled, i will give the setting a try thanks, i did check today but the appears to only be one adjustment and not a low and high speed setting as i thought there might be