Boat cought on fire again

Aircraft powered airboat discussion.
Post Reply
deerhuntindev
Southern Airboat Member
Posts: 8
Joined: Mon Feb 18, 2013 9:41 pm
Location: Polk City Fl

Boat cought on fire again

Post by deerhuntindev »

Have a franklin 165. The boat woundnt start up then finally it fired up and then backfired when i look down my carb was a big ball of fire. So i had my carb rebuilt an just put it on today. The motor just kept turning over with out fireing up, so i got mad and walked away for a hour then tried agin. After 5 mins she fired up an backfired immediately. An again my rebuilt carb was on fire. This is the 2nd time its done this. Anybody know what is out of wack?
boatair
Site Supporter - VII
Site Supporter - VII
Posts: 198
Joined: Tue Jan 11, 2011 5:34 pm
Location: Vero Beach, FL.

Re: Boat cought on fire again

Post by boatair »

Have you checked your mags?
boatair
Site Supporter - VII
Site Supporter - VII
Posts: 198
Joined: Tue Jan 11, 2011 5:34 pm
Location: Vero Beach, FL.

Re: Boat cought on fire again

Post by boatair »

Plugs?
deerhuntindev
Southern Airboat Member
Posts: 8
Joined: Mon Feb 18, 2013 9:41 pm
Location: Polk City Fl

Re: Boat cought on fire again

Post by deerhuntindev »

Plugs are all new and im gettin fire from all of them. I dont want to pull my mags off because im not good on aircarft. This is my first aircraft boat so im still learning them
Cutler
Southern Airboat Member
Posts: 211
Joined: Tue Feb 21, 2012 8:10 pm
Location: Miami

Re: Boat cought on fire again

Post by Cutler »

My guess is you have a timing issue not a carb issue
User avatar
Deano
Site Supporter - V
Site Supporter - V
Posts: 4597
Joined: Thu Jan 06, 2005 11:16 am
Location: Inverness, FL

Re: Boat cought on fire again

Post by Deano »

I'd say that's a pretty good guess. :thumbleft:

IF the plugs fire with the intake valve in any postion other than fully
closed, the carb will have very little choice about what happens next.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan
User avatar
kajunoutlaw
Site Supporter - II
Site Supporter - II
Posts: 1201
Joined: Fri Nov 30, 2012 5:03 am
Location: New Iberia, LA

Re: Boat cought on fire again

Post by kajunoutlaw »

Try to search for a "mag" manual on line. It should tell you how to set your timing. That is where I would start anyway.
Great minds discuss ideas, Average minds discuss events, small minds discuss people.
Adm. Hyman G. Rickover
User avatar
Wild Bill
Site Supporter - I
Site Supporter - I
Posts: 1731
Joined: Sat Feb 09, 2008 7:28 pm
Location: Great White North

Re: Boat cought on fire again

Post by Wild Bill »

While your playing with your mags. If the carb starts on fire again turn the mags off and keep cranking, fire should go out.

Could also be rroken valve spring or dropped intake valve seat
boobidges
Southern Airboat Member
Posts: 495
Joined: Sat Sep 29, 2007 5:06 pm

Re: Boat cought on fire again

Post by boobidges »

Classic aire in Georgia. Mans nameis Bruce Kown. I boughtmy manual from him. Great guy , very knowledgeable. Set timing at 25degrees before tdc
boobidges
Southern Airboat Member
Posts: 495
Joined: Sat Sep 29, 2007 5:06 pm

Re: Boat cought on fire again

Post by boobidges »

Classic aire in Georgia. Mans nameis Bruce Kown. I boughtmy manual from him. Great guy , very knowledgeable. Set timing at 25degrees before tdc
User avatar
HAMMERHEAD
Southern Airboat Member
Posts: 2269
Joined: Mon Jan 11, 2010 7:58 pm
Location: GAINESVILLE

Re: Boat cought on fire again

Post by HAMMERHEAD »

yes check compression on eachcylinder sounds like a spring or seat and plug is firing with intake valve open. easy to check and eliminate for trouble shooting.
User avatar
FLCGC4H2O
Southern Airboat Member
Posts: 179
Joined: Thu Jun 24, 2010 8:16 pm
Location: Live in G'ville, From Cocoa

Re: Boat cought on fire again

Post by FLCGC4H2O »

Valve(s) are not seating correctly allowing pressurized ignited fuel to get pushed back through the inlet port to the carb.
check valves seats, and all mating surfaces.
Just a thought.
14' Alumitech 383 SBC 2.68 Rotator 3 blade 80" Sens. R
Polished sst rigging 3/8 poly goes where you want it to.
User avatar
John Fenner
Southern Airboat Member
Posts: 2910
Joined: Tue Feb 14, 2012 12:26 pm
Location: Miami(Cuba) Fl.

Re: Boat cought on fire again

Post by John Fenner »

Need to check your valve lash.
I never finish anyth,,,.
Post Reply

Return to “Aircraft Power Only”