other Fuel Boiling in Carb

[nedfo72]

Hey fairly new to the forum (first post) and new to my '02 as of April. So go easy on me. 

 

It has a weber 32/36 and I've been having the problem with there being a puddle of fuel in the intake manifold when I go to start it. I took it apart and cleaned it all, the needle and everything was in good shape. But I noticed last time I got it going and drove it that after a shut it off, there was fuel boiling in the float chamber and fuel was just pouring into the intake manifold. I adjusted the choke and got an adapter to put the stock air cleaner on and it seems like it's been worse lately so I think I need to adjust the choke to let more air in (it's also a lot worse now that it's summer). It runs like a dream when it's started and warm, just a pain to get it started with all of that fuel in the intake manifold. 

 

Please excuse any newb questions/comments lol 

Thanks

[zinz]

Welcome to summertime and the Weber 32/36.... very common problem.

 

Google Search in the upper right for "percolation" or "vapor lock" and Weber 32/36.

 

Esty had this exact problem discussed about 2 weeks ago.  There is a vent hole that you can plug on the top of the carb, as well as placing a phenolic spacer under the carb.

 

Depending on how hot your location is, you may only reduce the problem.... I could never completely solve it here during the heat of summer, so I went with side drafts

 

Ed Z

[esty]

i don't know if the temporary problem i had was vapor lock, i doubt it...if you don't have a spacer between the carb & intake manifold, you should get one...it helps insulate the carb from the warm/hot manifold

 

https://www.pegasusautoracing.com/productdetails.asp?RecID=3585

[Gil. H.]

I also read a post on the "vapor lock" thread about a member who would keep a cold/wet towel on the carb/intake manifold cool enough to prevent the lock.

Not an ideal response, but another alternative. Go with the spacer first and make sure you've got a good tight seal on the manifold/spacer/carb.

['76mintgrün'02]

are you running a stock mechanical fuel pump? 

Webers don't like much pressure (three or four psi, I think).

It sounds as if residual pressure left in the line is being pushed through the carb.

 

Originally there was a pressure relief / bypass valve in the system which sent fuel back to the tank.

Is any of that still involved in the equation, or is it a straight shot from the pump to the carb?

 

Did you  check/adjust the float height while you were in there cleaning?

Is it plastic or brass?

 

Welcome aboard!

 

Do you have any photos you could add?

[TobyB]

You can also rig a 'carb fan' to run for 20 minutes or so after the engine's shut off.  Toyota did this on the later carbed Land Cruisers- and it worked.

Nissan did it to the longer L series engines, too.

 

t

[jimk]

Before I dumped all that dark age technology (and went to EFI), I put an early heater valve (the small one) in the hose from the water outlet to the manifold and with an aftermarket choke cable, shut the hot water off about 2 blocks from home.  Hot water from the head outlet flows all the time whether the heater is on or not.  The vaporization process cooled the intake/carb to put an end to boil out and stinky garage.  But that's history for me.

[Koblenz]

i don't know if the temporary problem i had was vapor lock, i doubt it...if you don't have a spacer between the carb & intake manifold, you should get one...it helps insulate the carb from the warm/hot manifold

 

https://www.pegasusautoracing.com/productdetails.asp?RecID=3585

Capture.JPG

Mine did the same thing.  Located in africa hot central Florida.  When I pulled into the garage I could hear it.  My garage (and second floor) smelled like a fuel farm.

 

Installed the phenolic and man what a difference.  If you don't have one. I would suggest you do. best money i have spent.

[zinz]

Before I dumped all that dark age technology (and went to EFI), I put an early heater valve (the small one) in the hose from the water outlet to the manifold and with an aftermarket choke cable, shut the hot water off about 2 blocks from home.Hot water from the head outlet flows all the time whether the heater is on or not.The vaporization process cooled the intake/carb to put an end to boil out and stinky garage.But that's history for me.

 

Ingenious, Jim! Well done...  With a couple of heater valves in the parts stash, I need to try this on the '75.  ...or put my extra set of Solexes on

 

back to the original post...

 

Here's the pic of the orifice on top of the 32/36 you can plug help the percolation problem.  You should definitely use a phenolic spacer under the carb, as well.

 

Best of luck...

Ed

[nedfo72]

Hey thanks for all of the replies guys. I really appreciate the help. I'll go ahead and order a spacer today. The only problem I might run into is clearance on the air cleaner. I already had to modify the adapter a bit. I can probably go down another half an inch on it though so I should be able to figure it out. 

[wegweiser]

I was just about to mention, that on some cars, with certain air filter set-ups, the spacers make things perilously tight, between carb/air filter and hood. Spacers are a good idea, just proceed with some caution. make sure your engine mounts are good, too! Rocking engines dent hoods frequently on these cars!

[Simeon]

You might want to consider removing the air filter adapter from the carb and altering the stock filter housing to fit. If you search the site there are lots of posts on the subject.

[Koblenz]

I was just about to mention, that on some cars, with certain air filter set-ups, the spacers make things perilously tight, between carb/air filter and hood.

I did not know this.  I guess I lucked out.  Again!

[AustrianVespaGuy]

FYI, if it's available in your area, running ethanol-free gas can help with this problem.  The 10% ethanol content of most gas greatly lowers the vapor pressure of it, making it much more prone to boil over.  Running pure gas may or may not be enough to fix your issue, but it's at least really easy to try out and see!

[zinz]

ugggh... don't get me started about ethanol in gasoline... such a boondoggle.  I sorely wish I had a pure gas station halfway close to me.  

 

Ed Z