Getting 10mpg with Weber. Please help!

[nickolai]

So recently I've started driving the weberized wagon more frequently, and it drives great, and has plenty of power, but it just kills me how fast it sucks down the gas. I haven't done a super accurate test, but through two tanks of gas, I estimate it's getting around 10mpg! It also makes a loud bang, almost like a gunshot, every time I turn it off. So obviously it's dumping in way to much fuel, but I don't know what to do to fix it. I'm a bit of a carb noob. I tried tuning it using this page as a guide:

http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm

However, I have the idle screw all the way out, and I still want it to idle lower, and I cant get the mixture screw to make any real noticeable change to how the engine runs.

If someone could explain to me what is wrong and how to fix it it would really make my day! Thanks.

[Loyale 2.7 Turbo]

Few info is Given and some Questions could help to Figure out what's Wrong, Like:

-is that a Brand New Weber intended (Jetted) for your Subie's Engine?

-Or is an Used one for other Engine?

-is a 32/36 or a 38/38?

But an easy answer could be this: The idle Screw has an O-Ring that could be Worn... also Jettings might be Wrong...

I Kindly suggest you to take it out to see how are the Jets and Check for worn gaskets.

Good Luck!

Kind Regards.

[nickolai]

Thanks for the reply. The carb is a brand new 32/36 from Redline, intended for ea71/81. I have it on an ea71.

[bheinen74]

redline does not have a good reputation, someone there needs to get better.

 

did you seal the adapter well, and block off the coolant passageway?

 

Is your choke functioning correctly.

[nickolai]

redline does not have a good reputation, someone there needs to get better.

Agreed. Most of the Redline kit was junk.

 

did you seal the adapter well, and block off the coolant passageway?

The gasket that Redline gave me was wrong, so I put some grease on the old gasket and reused it. The coolant passage is blocked.

 

Is your choke functioning correctly.

I don't know how to check that.

[El Presidente]

For a carb noob, you picked probably one of the hardest carbs to learn on, but after you figure it out, damn near any other carb will be a cake walk. Don't get me wrong, Webers are one of the best designed carbs and can be tuned more precisely than most, which is a double edge sword.

 

Redline has a bunch of dicks working there and they will not help you and they do not care. We'll help you out and get you back in the 20-30 MPG range.

 

Use RTV, or copper coat to seal gaskets, not grease. It works, but I would only do it if I had too...like if I was on the side of a trail doing a carb rebuild. I wouldn't expect it to seal for very long.

 

Your target idle range when warm should be around 550-650 RPM.. Where are you at?

 

When its idling, you shouldn't heard sharp popping(almost like frying bacon) coming from the air horn. It should just sound like air being sucked in.

 

You said the idle speed screw is all the way out, how many turns is your fuel mix screw out? Ideal range on the fuel mix screw is 1 1/4-2 1/4 turns out and the idle speed screw should be somewhere between 0 to 3/4 turn out.

 

Whats your cold idle speed? Does it "kick down" after its warm?

 

Look for a round little can that gets 12V when running...I'm assuming you have electric choke, thats your choke coil and should be secured with three small screws. Loosening those screws and rotating the can is how you adjust your choke, but for now just make sure its not holding the throttle open. If it is, just back it off. Wait on setting your cold idle speed until you get the warm idle figured out, but if your choke is too tight, it will think its always cold and always dump extra fuel and run a fast idle. Your cold idle is set by another screw near the choke coil, thats your cold idle screw, sometimes they can be cranked it so far, it will hold the throttle open regardless of what the choke is doing so check that too.

[T'subaru]

http://www.webercarbsdirect.com/product_p/43914.060.htm

might help with your shut off issues

tech info and trouble shooting info as well

http://www.webercarbsdirect.com/v/vspfiles/images/Weber%20Trouble%20Shooting%20Guide.pdf

Edited May 18, 2011 by T'subaru

[nickolai]

...thats your cold idle screw, sometimes they can be cranked it so far, it will hold the throttle open regardless of what the choke is doing so check that too.

Thanks for pointing that out. I never would have found it on my own. It was definitely in too far causing the high idle. I backed it out some, got the idle to where I liked it, and then readjusted the mixture screw to 2 turns out. I took it for a short test run and it seems to be doing great! No more backfiring on shutoff!

I still have yet to do a mpg test, that will probably take a couple days.

[nickolai]

tech info and trouble shooting info as well

http://www.webercarbsdirect.com/v/vspfiles/images/Weber%20Trouble%20Shooting%20Guide.pdf

Thanks! A lot of good info on that page.

[bheinen74]

2 turns out good here.

To get a little better MPG, should it be turned 1/4 more which way, in or out?

 

mine runs good either at 2, or at 1 3/4 or at 2 1/4 I would like to know which will give better fuel mileages.

[El Presidente]

2 turns out good here.

To get a little better MPG, should it be turned 1/4 more which way, in or out?

 

mine runs good either at 2, or at 1 3/4 or at 2 1/4 I would like to know which will give better fuel mileages.

 

Unfortunately theres no right answer:

 

Turning it in, leans the mix, out will richen it, but....the best setting depends on the motor its on, outside temps, elevation and fuel being used(Ethonal free gasoline will get you better MPG's, because it runs better on a leaner setting compared to ethanol gas)

 

1 1/4 or less turns out is lean for the carb, meaning the fuel mix screw is compensating for over jetting(jets too big). Over 2 1/4 turns out means the fuel mix screw is compensating for to small jets or a vacuum leak. The fuel mix screw is the fine adjustment for the idle curcit which is whats used up to around 2,400-3,000 rpm(which depends on air correctors and emulsions tubes).

 

How you drive can also be a factor on where the screw should be. I personally adjust to the leanest setting that gets a smooth idle, then back it off slightly to help performance. I couldn't tell you exactly how much I back the screw off, because I don't know.

 

I've been working on carbs so long I shut my eyes to hear better, put my hand on the motor for feel and go off what the motor tells me. It sounds like magic, but once you stop thinking and listen to the motor, you can find that spot where its just plain happy. Snap the throttle quickly open(I mean quick!) when enrichening after finding the best lean idle too. You want a responsive fast rev up that doesn't lag, or bog down when the throttle is snapped. I also smell the exhaust by putting my hand into the exhaust stream coming from the tail pipe to divert SOME exhaust to my nose(don't put your face in front of the tail pipe OK), your not gonna get high, so don't over do it, just a smell. If it burns your nose and smells light and "dry" your lean, if it smells heavy and of course like gasoline, your rich. I describe a good mix as well balanced, with a slight round smell, a very slight hint of gas that almost smells sweet. I might be getting old, but trying to describe years of experience can hard. Just don't run it too lean though....You can get awesome MPG's on some carters if you run them real lean at a high idle(I've seen 25-28MPG's on old 60's V8's), but you'll also get detonation, and eventually melted pistons and missing rods..I've seen it.

[Freds404]

what jets are you running? I am having trouble as well. It appears to be lean with the 60 and 50 idle jets.