Weber on a 22R dumping fuel

rattlecanpaint

rattlecanpaint

Well-Known Member
Joined
Apr 18, 2005
Location
Winston Salem
First a little history. It's been running rich since I got it but it ran OK. Drove it to work the last 3 days, drove it around last night and on the way home got fuel. This was about 11:30 last night. Today on the way to work the 4runner started running like absolute crap. Fortunately it's only a mile and a half to work and there's only one stop light. Had to keep one foot on the gas to keep it (sort of) running. It's running really rich, smells horrible and is blowing black smoke like a diesel. Carb only has about 1000 miles on it. Had a buddy pinch off the fuel line to the carb with his fingers and it purrs like a kitten. Let off and it continues to run OK till you give it some gas then it's back to barely running, missing, bucking etc. We figured the pressure regulator in the fuel pump was bad so I installed a new one. Still does it.

When I removed the air cleaner and looked down the throat of the carb there is (what seems to me like) way too much fuel coming out of the carb at just off idle. I'm guessing you should just see a mist of fuel, not liquid pouring onto the throttle plate. Am I wrong here? I pulled the top off the carb and checked the needle thinking there might have been something stuck in it but it's clean. Pulled the air jets off to see if they were plugged but they look clean too. Any ideas, or is it just possible bad gas? (In dealing with BMW's and bad gas they won't idle or in some cases even start but it's a constant thing not like this one where it will idle after pinching off the fuel line. Anyone heard of anything like this or have any ideas?
 
I'm running the stock mechanical fuel pump. That's why I replaced it, because I thought the regulator (inside the pump) had crapped out.
 
I don't think there's a regulator, per se. It should have a bypass line that's a smaller diameter than the outlet. When the bowl is full and the float closes the inlet, then it sends the pumped fuel down the return. The Weber seat might not seal off as much pressure as the stocker. Don't try one of the dial-type regulators, they're junk. The first think I'd check, though, is the float level. If it's high, you'll have these problems. Shake the float to make sure it's not leaking. Then I'd be tempted to replace the needle and seat just in case it's bad.
 
"power valve"

if you take the air cleaner off and there is fuel coming out of the booster venturi at idle then the " power valve" is bad. when you take the top off the carb it is the long thing with a spring on it that fits in between the float chambers. it is held to the top piece of the carb with 3 screws. i think when you go to order the part it is called a " fuel enrichment diaphragm ". the actually "power valve is in the bottom of the bowl. the diaphragm simply opens and shuts it. the ethanol is the gas is rough on all the diaphragms in the carb .
 
Dirt Mcgert said:
if you take the air cleaner off and there is fuel coming out of the booster venturi at idle then the " power valve" is bad. when you take the top off the carb it is the long thing with a spring on it that fits in between the float chambers. it is held to the top piece of the carb with 3 screws. i think when you go to order the part it is called a " fuel enrichment diaphragm ". the actually "power valve is in the bottom of the bowl. the diaphragm simply opens and shuts it. the ethanol is the gas is rough on all the diaphragms in the carb .
Click to expand...
Would I be able to see a tear or something in the diaphragm? (Glad you gave your input. I was wondering what that was.) The carb has less than 2k miles on it, would the diaphragm deteriorate that quickly?
 
yes and can take it out and inspect it. problem is the diaphragm is some type of rubber coated fabric (unless material has been changed) that makes it difficult to see a tear or break, also the diaphragm is small ( slightly larger than a nickle ).and the other problem is reinstalling it. when you buy a new one it comes with a clip that holds the diaphragm in the proper position , you then snug down the 3 screws, pull the clip out and finishing tightening the screws. this can be done with out the clip if you have a third hand or a buddy willing to help. one method i have used with success in determining if the diaphragm has failed is to remove the top of the carb. if you notice on the gasket there are a few holes in it. well, one of these holes is for the vacuum passage that operates the diaphragm.Now with the top of the carb in hand. and with a rubber glove on (just your finger wont seal the hole right). Push the diaphragm in by the spring, then cover the vacuum passage with your finger.(use trial and error to find the correct hole). if you have sealed the vacuum passage and the diaphragm is good. the spring should remain in place until you release the finger on the passage. then it will rapidly open .if the diaphragm wont hold against the spring ,chances are it has failed. As far as it only having 2000 miles on it, I have had them go bad after only a few months. from my experience millage dose not cause them to fail. bad fuel and time dose. Also is this carb, new , used , rebuilt, has it sat for a long time with fuel in it ? anything is possible . I dont know what exact carb you have . but here is a link to the part http://www.webercarbsdirect.com/product_p/57804.097.htm
 
I'll give it a try tomorrow! Thanks! Carb is a new 32/36. It sat for a little over a year with fuel in it while I finished my build. (It had to be semi mobile cause it was at work and so needed to appear to be a DD.)
 
Just throwing this out.
Webers are designed to run with low pressure but high volume.
The ideally only need 3lbs. er so of pressure ... much more than that can over power the needle valve and push fuel through.


Matt
 
Hope you figure this out...my new Weber is running VERY rich....thinking about a fuel pressure regulator...:confused:
 
Just throwing this out.
Webers are designed to run with low pressure but high volume.
The ideally only need 3lbs. er so of pressure ... much more than that can over power the needle valve and push fuel through.





this is very true . the stock mechanical fuel pump supplies the correct pressure but not enough volume. one dead give-a-away is the fuel lines. the stock carb uses 6mm(1/4in) fuel lines and the fuel inlet on a weber is 9.5mm(3/8in). and if you have ever compared the needle and seat of a stock carb to a weber the differences are drastic. I guess for a real world example would be. That when i had a weber on my truck. At sustained WOT, under load (20-30 seconds) it would starve for fuel and skip, miss fire , ect . On a friends truck with the same motor, same carb and a $25 universal 3/8in fuel pump(3 to 5 lbs), and under the exact same circumstances (same mud hole). His has no problems. and I was changing fuel filters once a year, while he has never changed his in 7 years.That leads me to believe it had to have been a fuel supply (volume) issue.
 
Dirt Mcgert said:
Just throwing this out.
Webers are designed to run with low pressure but high volume.
The ideally only need 3lbs. er so of pressure ... much more than that can over power the needle valve and push fuel through.





this is very true . the stock mechanical fuel pump supplies the correct pressure but not enough volume. one dead give-a-away is the fuel lines. the stock carb uses 6mm(1/4in) fuel lines and the fuel inlet on a weber is 9.5mm(3/8in). and if you have ever compared the needle and seat of a stock carb to a weber the differences are drastic. I guess for a real world example would be. That when i had a weber on my truck. At sustained WOT, under load (20-30 seconds) it would starve for fuel and skip, miss fire , ect . On a friends truck with the same motor, same carb and a $25 universal 3/8in fuel pump(3 to 5 lbs), and under the exact same circumstances (same mud hole). His has no problems. and I was changing fuel filters once a year, while he has never changed his in 7 years.That leads me to believe it had to have been a fuel supply (volume) issue.
Click to expand...
hate to jack this thread...but where did he get the fuel pump? mechanical?
 
Dirt Mcgert said:
Just throwing this out.
Webers are designed to run with low pressure but high volume.
The ideally only need 3lbs. er so of pressure ... much more than that can over power the needle valve and push fuel through.





this is very true . the stock mechanical fuel pump supplies the correct pressure but not enough volume. one dead give-a-away is the fuel lines. the stock carb uses 6mm(1/4in) fuel lines and the fuel inlet on a weber is 9.5mm(3/8in). and if you have ever compared the needle and seat of a stock carb to a weber the differences are drastic. I guess for a real world example would be. That when i had a weber on my truck. At sustained WOT, under load (20-30 seconds) it would starve for fuel and skip, miss fire , ect . On a friends truck with the same motor, same carb and a $25 universal 3/8in fuel pump(3 to 5 lbs), and under the exact same circumstances (same mud hole). His has no problems. and I was changing fuel filters once a year, while he has never changed his in 7 years.That leads me to believe it had to have been a fuel supply (volume) issue.
Click to expand...
My problem is definitely NOT a lack of fuel. Plugs are black as coal. Probably to the point I'll have to replace them to tune the carb.
 
So I pulled the top back off the carb and sealed the hole with a gloved finger. It won't hold the spring back but when I let off with my finger I can hear the air suck back in. Seems like the spring is too much for the diaphragm. Can I just eliminate this whole part and leave the power valve in it to test?
 
Well, it looks like it's the power valve assembly. I just took it out and have been driving it. Has one heck of a flat spot on accel though. Got one on order and my book finally come in so I now know how it works with emulsion tubes and what-not. Gonna pull the main jet out of it and go a bit smaller too to try and lean it out some. Thanks for the replies!
 
Finally got me power valve assembly AND the time to put it in. The new ones diaphragm is 3 times thicker than the original. Works good so far. Drove to Applebee's for dinner and it runs much better with a functioning power valve. Still running rich though. While I had it apart I pulled both of the jets out to see what sized they were but there's no numbers on them like the air adjustment jets. Any idea's how to find out what size they are?
 
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