18hp vtwin needs a new carb, maybe...?
 

I bought a 18hp big block from CPP about six or seven years ago. It's been running great for the last few years but started having some issues two weeks ago. Sometimes, it would start up and immediately die. I could try several times in a row, and it would start up, but die within 1 or 2 seconds. Sometimes, it would start up and run like a champ. I could drive it around the campground, let it idle for 10 minutes, and drive it some more with no problems at all. And then five minutes later, it wouldn't start again.

I'm no mechanic, but I did change the fuel filters and clean out the carburetor as best I could. And by that, I mean I took off the top and cleaned what I could see. I also took off the float and the little stopper to make sure it's getting fuel. When I turned it over, gas sprayed several inches so I know it's getting fuel. After trying to clean it out myself, it still did the same thing.

I took it to a lawn equipment/small engine place and described what was happening. They called me the next day and said the carb just had too much gunk in it and it needed a new carb. Is this possible? If it runs great part of the time, how could it need a new carb? He said he actually removed it from the engine to get a good look at it, which I didn't do. Is it possible it's so dirty he can't clean it, or is he selling me a new carb I don't actually need? As usual, I feel like i'm getting ripped off. FYI: I reluctantly agreed so i'm getting a new carb and I should get it back tomorrow. I told him I wanted the old one to clean up and keep as a spare, but I really want to look at it and see how bad it is. Well, not that I would know what's very bad or a little bad when it comes to gunk... LOL

I made this video and put it on youtube to show what it's doing: https://www.youtube.com/watch?v=7aGAoc2eAJs

Any opinions are welcome.

Re: 18hp vtwin needs a new carb, maybe...?
 

Someone suggested to me at one time about a bad ground issue. It's worth the time to take a look rather than buy a new carb and not fix the issue.


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Re: 18hp vtwin needs a new carb, maybe...?
 

How long does it sit in the cold months? Do you use gas stabilizer in the winter? Even in cold weather gas evaporates and glues up the carb. Have you drained your winter gas and replaced it? When you get your old carb back, soak it in carb cleaner. You'll have a terrible time cleaning it if you just let it dry out. Everything will be varnished up bad - jets included.

Re: 18hp vtwin needs a new carb, maybe...?
 

What's the air filter look like?

Re: 18hp vtwin needs a new carb, maybe...?
 

May want to do an oil change and a set of plugs just looking at all the dust on that lil motor. And the carb could be rebuilt but the shop makes more money from selling parts and no liability.

Re: 18hp vtwin needs a new carb, maybe...?
 

You can have junk floating around in the bowl and it will suck into a jet and poof it cuts out. Next time it runs fine and you never know, poof it does it again. But I have to say the only reason I ever bought a carb (the same carb, a replacement) is either something broke like the throttle lever came off, or the throttle shaft wore into the body so much it leaked air badly. You can clean a carb, I've never found anything from gas you can't remove or soak out. Though today with a clone engine you can buy a new carb for like $15, its almost cheaper than working on one if yours is really dirty or you can't find the issue with it.

So I doubt its worn out or that dirty, I would say they want to sell you a carb for some reason other than your problems. They likely make more money that way and are sure it is clean because its new. In case they miss something they do not have to take it off and clean it again. I mean really, if they can charge for it they would drop a whole new engine in it. It would be sure to fix whatever is wrong with it right, even just junk in the carb. And they might swap it out faster than troubleshooting the fuel and ignition systems.

Re: 18hp vtwin needs a new carb, maybe...?
 

Long story short on all of these, give that SOB a good cleaning and check for anything loose/broken. It's probably something simple.


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Re: 18hp vtwin needs a new carb, maybe...?
 

Brand new. I replaced when this issue started happening, but no change.

Re: 18hp vtwin needs a new carb, maybe...?
 

Thanks everyone for the replies. I'm pretty sure I bought a new carb when the old one just needed a good cleaning, but at least it runs great now. I guess now I need to start using some kind of carb cleaner additive to prevent this from happening again.

Re: 18hp vtwin needs a new carb, maybe...?
 

Gas stabilizer for the time it isn't ridden would be best.

Re: 18hp vtwin needs a new carb, maybe...?
 

Or install a shut off and run it out of gas in the off season.

Re: 18hp vtwin needs a new carb, maybe...?
 

I agree with the idea of a gas shut off valve. If possible draining the carburetor would be better. The VC 460 comes with a drain -- most clones have a drain bolt in the fuel bowl.

Re: 18hp vtwin needs a new carb, maybe...?
 

i'll look for that this fall when i winterize my camper and shut everything down.

thanks again for the help.

Re: 18hp vtwin needs a new carb, maybe...?
 

Or wash it every so often, that may help also


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