GPU carb rebuild

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Southern Airboat Member
Posts: 6
Joined: Tue Jan 29, 2019 11:14 am

GPU carb rebuild

Post by Polbear »

Recently bought a boat with a 220 gpu that was running incredibly lean. After running would diesel on shutdown. Crazy good fuel economy though.

Replaced o-rings that seal the surface between intake elbows and cylinder heads. During replacement found the rubber had consistency matching that of a rice Krispy treat and didn't seal the elbows. Also replaced spark plugs at same time. Boat ran much better but different symptom manifested.

Boat idled much better but still little rough and very hard to start. When throttle was stabbed it would pop, stumble and then pickup.

Pulled fuel inlet barb off of carb and a bunch of junk came out. The sintered bronze filter was clogged. Went to 3 different auto parts stores and none of them had it.

So temporary bandaid/ improvement was to install a primer bulb before the electric fuel pump and glass fuel filter with screen after. Boat now starts significantly easier and runs/ idles much better. I know part of my starting issue was fuel draining and going back into the tank but between the debris found at the carb and a sneaking suspicion that my acceleration pump diaphragm is tired I'd like to rebuild the carb.

None of the local auto parts stores carry any kits. Amazon has a ton for 2 barrel Holley 500 carbs but I'm unsure of what to get. I'd also like to replace the now missing bronze filter in the carb.

Any help or a point in the right direction would be incredibly appreciated!

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Southern Airboat Member
Posts: 26
Joined: Sun Mar 16, 2014 12:10 am

Re: GPU carb rebuild

Post by mfreem »

I have a GPU with a holly carb. It is not hard to rebuild after a couple youtube videos, but you are going to have to completely rebuild it. Actually that is something you should become proficient with airboating in the middle of nowhere. Yes you could buy a new one and it will probably work MUCH better than what you have on it, you would still need to buy a jet kit, vacuum gauge and couple power valves to tune it just right. You don’t want a motor running lean. Rich is better all day, especially on a GPU. If you need the exact carb model you have just look you’ll find it stamped. The rebuild kits are very generic though and it’s a 2300 kit I believe. After that make sure all intake tube rubber collars are new, as well as add some RTV to where the tubes meet the cylinder heads. You don’t want any leaks. I forgot to say add a couple carb base plate gaskets to your cart, don’t reuse anything. Gonna need some good ole parts cleaner dip and a couple cans of carb cleaning spray. Good luck!

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