Need some help

[NAMBA860]

Im not new to nitro but started running it again lately. I built 2 .45 monos 1 with k/b 7.5 and the other with an OS .46. Both good clean no damaged engines. Head clearance and timing set by a good engine builder both boats run about 4-5 laps then die for no reason. Im running BAM 50% nitro fuel and have tried several different glow pugs. Both are new hulls and I dont know if both boats are getting water in them or what. I have run them rich I have run them on the lean side and I have run them in between. Props are x450 3 blades and pipe lengths from the exhaust flange on the crankcase to the high side of the pipe is 9.5 inches. I have checked the cooling lines for leaks with vacuum test on them and no leaks

 

[Tom Levescy]

are the tanks new ?

 

[NAMBA860]

Yes running brand new two 8 oz Dubro tanks in each boat

 

[Richard Hartley]

Might try a small header tank like a one or two oz

that way fuel will not tend to slosh over and expose pickup if you have to correct your track

I just started running a 40 size seaducer with a header and it works great

also you didnt specify if you were running pressure

Richard

 

[FloridaScaleBoater]

Did you use 5/32" copper tube for your plumbing?

Is the plug still good after you 4-5 laps or blown?

Are there any water droplets on the plug when you pull them to check them?

You day you vacuum tested the cooling system?

How about pressure test, since the system is pressurized while running.

Fuel tank feed test. Fill tanks up. Unhook pipe pressure line. Make am extension fuel tube hooked to fuel suction line.

Into a clean painters cup, siphon fuel from tank, once it starts to flow, let it gravity feed into painters cup.

If it stops flowing (naturally) before the tanks are empty, you have a fuel feed/plumbing problem.

 

[Mike Cathey]

Bearings are a possibility as well.

 

[John Beardslee]

8 ozs of fuel seems small for a 46, is there any fuel in it when you bring it in?

Thanks John

 

[JRXHydros]

Fuel runs away from pickup,sucks in air bubbles flame out. Peace Out.

JRX

 

[John Beardslee]

8 ozs of fuel seems small for a 46, is there any fuel in it when you bring it in?

Thanks John

Sorry, missed you are running two. A 1 or 2 oz hopper tank will probably cure it then

 

[NAMBA860]

Maybe this will shed some light. I have broke 3 manuel fuel pumps using this fuel. If the fuel can sits for a week or more I go to try and crank it and the pump handle is locked up.

 

[NAMBA860]

I have never lost a glow plug on either of the engines yet. I have never seen water on the plugs either. Its funny how both boats do the same thing and I have been using this twin fuel tank set up for more then 35 years and have never had problems before

 

[Richard Hartley]

I have had that happen with new fuel

the problem there is more than likely old tubing in pump

Try the Header if it still happens that the motor dies it could be as Mike Cathey stated Bearings

 

[NAMBA860]

I did the fuel siphon test like said by FSB on both boats fuel systems and they both passed with flying colors. I think Im down to water getting the hull or bad fuel. Does anybody have any ideas on putting something over the venturi and maybe point it up so the opening isnt so low in the hull and able to pick water up.

 

[NAMBA860]

Im going to try a new set of bearings and see what happens

 

[Patrick Mulvany]

You answered your own question!!! You say your manual fuel pump has locked up three times?? Time to go to Performance/O'Donnel or Morgan fuels!! If the pump won't work the motor won't like it!!

 

[rick lindow]

just out of curiosity,(1) around the strut area is there room for the water to pass out of the hull by the strut/shaft log, or strut. (2) did you (SILICONE AROUND STRUT /SHAFT LOG) ? (3) Strut bringing it in due to splashing or forcing the water inward from the face of the strut ? I also had a problem with my Dubro manuel pump I would have to loosen screws on housing from time to time it would free up re snug screws all good . I don't know Rick

 

[NAMBA860]

Its a pretty tight fit where the strut buts up against the transom

 

[rick lindow]

Shane, I should have ask you what strut setup are you running, sorry. What I had experienced in the past was I sealed around shaft log where it passes through the back of the transom, it trapped water in the boat and after a few laps it would die, of course when you go pick up your boat in the retrieve boat it would have water in it, so I was not sure what was really going on. I was running the Speedmaster stinger type adjustable strut, after looking at other set ups by other people I removed all the RTV from around the shaft where it passed through transom and the boat self drained problem was gone I was thinking keep the inside as dry as possible,i did not want to test my radio box seals every time it would die,out of fuel ect. I created my problem! not saying this is yours just asking. Rick

 

[Rokieboater]

When the boat dies is one tank empty and the second tank full?

 

[Grimracer]

Its not the fuel..

I am with Roberts lead.. I have had bad results with two tanks even with a header tank. The motor will change tune from tank to tank. I have tried a bunch of stuff to control this but just not worth it. Its best to see if you can just get one tank in the boat.

Grim

BTY.. the fuel pump locking up is fixable.. Super annoying but fixable. BTY.. to get by for now remove the sticker on the pump and loosen the 1.5mm set screw below the decal.. Just a PINCH will do it. At least it will get you going again.