Why I say most people can't/shouldn't rebuild a carburetor.

[Way2slow]

My brother's 20hp 2stroke Merc was a prime example.  He has owned a construction company with lots of heavy equipment, plus messing with old cars all his life and has done a most of his own maintenance, so he is not a stranger to turning wrenches. 

His motor sat up for a couple of years and as a result, the only way he could get it to run was by spraying gas in the carb.  He asked me about it and I told him 95% of the time that was because the main jet was plugged.  To get to it on that carb, it had to come off the motor, so he bought a kit and rebuilt it.  Puts it back on and still has the same problem.  He calls me and asked what to do now, he rebuilt the carburetor and that didn't fix the problem.  With this motor, the fuel pump is built into the carburetor, so other than making sure it was getting gas to the pump, there was not much else to check, so I told him to bring the whole boat and motor to my house so I could check it out.  After checking the rest of the fuel delivery system, I pulled the carburetor off and went through it my way.  Since all the gaskets were new, I didn't worry about needing another kit.  While it "looked clean inside" I still went through everything the way I normally go through carbs.   Put it back on and it ran like a top.   

[volzfan59]

I've rebuilt several carbs over the years, some worked out, some didn't. An old GM quadrajet that was modified into a racing carb did me in. Never again, there are folks, such as yourself that get it right all the time. I fall into the "shouldn't" category.

[Darth-Baiter]

what was the problem?

 

my best carb rebuild was in front of a janky autoparts/grocery store in some backwoods town in TEX.  someone in our caravan to deer camp came up limp.  I used a few screwdrivers, and my leatherman, and a can of carb spray.  someone used foil as a "helicoil" for the bolt that holds down the air filter.  the foil came apart and got stuck in the main jets.   it ran like a champ!!  we never saw a deer probably because everything smelled like gas.  

 

hahah..

1 minute ago, volzfan59 said:

I've rebuilt several carbs over the years, some worked out, some didn't. An old GM quadrajet that was modified into a racing carb did me in. Never again, there are folks, such as yourself that get it right all the time. I fall into the "shouldn't" category.

that is a difficult carb to rebuild.  yeeshs...any quadrajet...yuck. 

[volzfan59]

8 minutes ago, Darth-Baiter said:

that is a difficult carb to rebuild.  yeeshs...any quadrajet...yuck. 

That was when I ran in the modified street division. Rules said you had to run a "stock" carb that would have came factory on the particular car. Mine looked stock from the outside ?.

[Darth-Baiter]

been awhile, but I seem to remember setting the bowl float was a nightmare.  

[Way2slow]

When I was 16, the Quadrojets and Holley Double Pumpers were what I cut my teeth on.  I was very lucky at the time and didn't realize it until later years, but there was an old man that had a shop across the street from our service station that liked me and pretty much mentored me through my early years with carburetors.  Old man Nunley, as we called, him, was the master guru of high-performance carbs in the Augusta Ga area back in the early 60s and was the one racers came to from miles around for getting the most power out of them.  So, at 16, I knew how to read sark plugs and change jets and metering rods to tune Quadrojets and make bunches of other modifications to them.

[Bankc]

I've rebuilt a few carburetors in my time.  They're usually not too bad, so long as you can work on it all in one sitting.  If you have to stop and come back to it later, it gets dicey.  

It's not hard work, but it does require focus. 

[Darth-Baiter]

i dont remember Holleys being that bad.  you had that port hole that allows you to set the bowl levels perfectly, and the jets are easily sized.    honestly, my friend Carl did it in his sleep and did mine most times.  i had gasket cleaning duty.  

[gim]

I took a small engines class in HS. In order to pass, you had to bring in a small engine, completely disassemble it, clean and lubricate all the internal parts, put it back together, and start it. If it started, you passed. If it did not start, you failed the class.

 

Mine started on the second pull.

[Susky River Rat]

I let the professionals handle it. I just metal things together for a living.

[Woody B]

Back when I was racing I converted a bunch of Holley Carbs to burn methanol.   I quit racing in '99 but still get a call every now and then inquiring about a carb for methanol.  

 

Every year there's fewer and fewer engines with carburetors.   Repairing them will soon be a lost art.    

[slonezp]

I don't cut my own hair either.

 

Background is in HVAC. I've done plenty of mechanical electrical diagnosis and work. My SuperDuty has almost 100K and is due for a tune up. I was quite surprised the V8 takes 16 plugs to do the tune up...Where the F have I been?

[Kirtley Howe]

3 hours ago, Woody B said:

Back when I was racing I converted a bunch of Holley Carbs to burn methanol.   I quit racing in '99 but still get a call every now and then inquiring about a carb for methanol.  

 

Every year there's fewer and fewer engines with carburetors.   Repairing them will soon be a lost art.    

I have only rebuilt 3 automotive carbs. I have probably rebuilt a hundred or so motorcycle carbs. And probably 20 or 25 outboard carbs. It is a skill with a pretty steep learning curve, but being broke is a great motivator, and I was broke a lot when I was younger. My current bike is a 1986 Suzuki Cavalcade Trike....it has 4 carbs. I have rebuilt them twice. Not a fun job, but rewarding. And to have a professional do the job is almost $300 plus parts, and I am way too cheap to pay that.

[TnRiver46]

Will one of y’all please swing by and poke out the jet on my chainsaw? Thanks in advance. Got a big tree down 

[Tennessee Boy]

The other day my brother in law couldn’t get his mower started.  I stared at it,  rubbed my chin and asked him try it.  It started right up.  What can I say,  some of us just have it.  ?

[flyfisher]

I rebuilt a lawnmower carb once and said screw that.  Not worth the effort to me and I doubt I will ever own another car with one so I am good for now.  My 69 greand wagoneer had one though and i did clean it but never rebuilt it.  I wish I knew what I know about cars now back then because that thing was a gem......

[Tennessee Boy]

1 hour ago, TnRiver46 said:

Will one of y’all please swing by and poke out the jet on my chainsaw? Thanks in advance. Got a big tree down 

I bought a $10 carburetor cleaning kit off Amazon and have fixed three small engines clogged up by ethanol gas.

[TnRiver46]

14 minutes ago, Tennessee Boy said:

I bought a $10 carburetor cleaning kit off Amazon and have fixed three small engines clogged up by ethanol gas.

You’re hired!!! 

[Bankc]

2 hours ago, Tennessee Boy said:

I bought a $10 carburetor cleaning kit off Amazon and have fixed three small engines clogged up by ethanol gas.

The carb on my lawnmower had gotten so bad, that I was rebuilding it every year.  I was getting tired of doing that, so I bought a replacement carb off Amazon for like $10-20, I don't remember.  It went in okay, but it's got a slightly different design, and the engine wanted to run at probably 4x's the speed it originally was set to!  I had to do some serious tweaking to get it down to 1.5x.  I've got every adjustment as far as it will go and the metal throttle rod is bent like crazy now.  It burns fuel quicker and is louder than I'd like, but it doesn't bog down in heavy wet grass anymore, so I'll live with the 1.5x speed.  Especially since this motor is found in other devices where it runs at the higher RPM.  I just need to make sure my blade stays balanced, and I'll be fine (I hope).  There are some more things I could do to bring it down further, but I'm over working on that thing.  The next time it needs the carburetor rebuilt, I'm just buying a new mower.  It's a good 15+ years old anyway.  

[Darth-Baiter]

i took the carb off a Honda EU2000 generator, cleaned it, and muttered a prayer.  the simple, tiny carbs freak me out.  i never get them to run.  this time, i did.  never again.  

[gim]

4 hours ago, Tennessee Boy said:

I bought a $10 carburetor cleaning kit off Amazon and have fixed three small engines clogged up by ethanol gas.

That's why I always put ethanol-free premium fuel in my "seasonal" engines, including my outboard motor.

[WRB]

Did mention I grew up working on a boat landing now called a marina, well rebuilding carburetors on the rental boat fleet was part of the job.

Tom

[Way2slow]

I guess I should have said, "if you don't know exactly how they work.  They are more than the piece with a big hole in the middle that pulls gas up out of the bowl.  Granted, a lot of the times it's just the crud that's left in the bottom of the bowl from the gas evaporating clogging up the main jet and if you are lucky, you clean it, put it back together and it works. However, they are much more complicated than that, so if you don't know how and what each one of those tiny little holes do and what to look for when rebuilding one, it usually won't work right, if at all.  A bad rebuild or a dirty carb that needs a rebuild can actually cause a lean condition that melts a piston. 

Then you have those like the one on this Mercury where the fuel pump and carburetor all one unit.  A lot of people don't really understand how a two stroke motor even works, much less how the fuel pump works and all the things involved with actually rebuilding it and making sure everything is doing what it's supposed to.

 

For example, how many know that the piston does not pull gas into the cylinder.  As the piston is coming down from the compression stroke, it's compressing/pressuring the crankcase.  As it gets down far enough to clear the intake ports in the side of the cylinder, the pressurized fuel charge is blown into the cylinder at fairly high velocity and just the right angles.  

It's also the pressurized crankcase that supplies a pressure pulse to the fuel pump to compress the diaphragm to pump the fuel and check valves in there keep gas going in one direction.

[airshot]

I grew up working at a marina back in the 60's, had to clean and rebuild carbs on all the rental boats.  Had far more problems with crud buildup back then, before we had ethenol fuels...gumout was developed and sold by the case long before ethenol fuel came out !! 

Honestly can say I have never had a crud builup with ethenol and been using it sense it came out..