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Is the port circled in red where i would hook up for a fuel return? http://i281.photobucket.com/albums/k...psa0zs3y2m.jpg
One other question. Whats this thing circled in red for? Also the one in yellow is the idle mixture adjustment correct?
http://i281.photobucket.com/albums/k...pszavvu7ag.jpg
Thanks guys.
There is no return on a Weber. But you want to use an electric fuel pump. I think the PSI should be 3 PSI. do not use the manual pump. It has way to much pressure.
The only vacuum line that hooks up is for the advance. If that yellow one you circled has a spring then yes it's the idle mix screw, but it's hard to see from the picture.
Here is a video on how to adjust the choke if it runs to rich for to long when cold.
https://www.youtube.com/watch?v=gviih8tqKxc
I think using a return line, using the port plugged with the brass fitting in your pic, is a good idea for a few reasons -- reduces the smell of gas fumes, saves fuel by keeping it from evaporating into the atmosphere. It can even smooth out the idle in some cases. But most here don't use it for simplicity's sake. It's up to you.
http://bbs.zuwharrie.com/content/top...9de8#msg761158
It does have an electric pump and pressure is set to 3.5psi. I'm gonna hook up a return line to that second port on the carb and drop fuel pressure down to 3psi and hopefully i get better gas mileage that way. It got about 15mpg on the highway with it so far. It has a slight miss at idle which i think is due to being too rich, but driving it does just fine.
One other question. Is the idle mixture screw just to get the idle smooth or does it effect the entire operating range of the engine?
it will affect the entire air fuel ratio to a degree. But you can always get a smaller main jet and that will cure the fuel problem. It does not need the return. 3.5 is just fine. If you hook up to that port you won't have any pressure at all.
You should preform a lean drop. What you do is.
With a warm engine.
First you turn in the idle mix and seat it just lightly. Then back it off 1 turn
Next you adjust the idle speed screw back tell the screw does not touch the stop. Then you give it 1 turn clockwise to open the throttle just a touch. Then try to start it.
This might be better with a second person to crank it over for you. I use a hand held switch on the starter.
Once you get it running you will adjust the speed screw tell it will run. It should be running like crap at this point. Now you turn out the mix screw 1/2 turn at a time tell it runs better. Then the speed screw clockwise. So now it should be running better but real fast.
Now turn the speed screw down tell it idles some what. Then adjust the mix screw to fix that. What you want to do is balance the speed with the mix. So once you think it's running good turn the mix screw tell it dies. Then turn it out 1 turn and restart. It should run nice and clean and idle smooth and shut down with out any engine run on.
They also explain how to do this in the Weber manual.
15 MPG highway with a 2.0 sounds like it's running too rich. Should be closer to 20+ MPG.
I'm completely ignorant when it comes to carbs, so that whole jetting talk is over my head at the moment. Besides the idle mixture screw are there any other adjusting screws on it to tune it, or is it just jets? It looks like there are 3 or 4 other adjustable screws on it but all the diagrams i've pulled up don't say what they are.
On another note, it does something that i have no clue if its normal or not. My fuel pump is wired to a switch i can turn off and on at will. If i turn the fuel pump off, the truck will continue to idle for about a minute or so before it eats up all the gas inside the carb and then dies. Is that normal on a carb? Engine turns off like it should when you turn the key off. Haven't checked to see how long it will run like that now that i have the return line hooked up.
Take a look in the manual section The first gen manual has a good explanation of how a carb works.
With the pump off it will take some time for the float bole to go empty.
As for jetting it's easy. You pull the top off the carb. and in the bottom of the bole is the main jets. There are 2 one main one secondary. Each venture of the carb has one. On the jet is a number marked on the jet. That is the size of the hole. You would want to go one or two sizes smaller. But look at the manual and you will have that ah ha moment.
After setting the idle speed and adjusting the mix, im still only getting about 16mpg. I just got done switching the setup around. Before i was fuel feed to carb, and on that secondary port on the carb i used as the return, i put the regulator on that side. I'm hoping carbs just dont like the regulator being at the end of the fuel supply like that(again know nothing about carbs, thats how its done on FI tho) so i took return line off the carb and blocked it. I put a t on my fuel feed line and have one going to the carb and the other is to the regulator, and regulator goes to return line. Oh and i readjusted the mix again after this. So if my mpgs are still crap after this, jet swapping time? Do i want to use a smaller main and secondary, or just a smaller main? Also are there any gaskets or seals that must be replaced whenever the jets are taken out?
In all honesty im not going to be satisfied until im getting 30mpgs with this, the engine should be able to do that no problem. Can i even get to that with a carb or am i wasting my time and i'll be better off converting to fuel injection? My 1g dsm gets better gas mileage than this truck...smh
pull the plugs and look at the electrode color - if it is black - rich, tan or light brown - good, white - lean. Check the float level according to the manual for the weber.
Plugs are black everytime i check them. Can i get a link or can you explain how to check the float? I've spent the past hour trying to find the info but have no luck.