wannagetrdone

Ok been having issues with my carb and the only thing I havent done is block off the fuel return line. Im not sure where to do this at thanks

myyota

What problems are you having ?. Blocking off the return line won`t fix anything.

wannagetrdone

Well ive installed a weber 34 34 carb. Followed the procedure for setting the idle mixture screws to the letter. It's starts and idles good but if its cold and u go to take off it will bog down under load sometimes even backfire a lil. After it warms up it runs good except occasionally it will hiccup sometimes once sometimes several times in a row. It only does that when u slow down and get back on the throttle. Another issue is sometimes it won't start after its warm unless you press the accel pedal down when tryin to start it. I don't know what else to try. I have the fuel pressure regulated a 3psi my mixture screws are good between 1.5 and 2 turns out and I've had timing anywhere from 0-8degrees without a difference in symptoms.

myyota

Try dropping the fuel presure down to 2.5 psi, 3 psi might still be a little high.

xxxtreme22r

I run my 32/36 at 3.5psi.

I just blocked off my line on the pump side with a bolt hose clamped in place at the end of the hose.

Mine falls on it's face a little if I drive right after the high idle kicks down. If I let it warm up a little bit longer, then I am good.

wannagetrdone

I've had the pressure all the way down to 2psi and as high as 4 and really couldn't notice much. I'm at a loss. I've had the carb on the truck for about two yrs but was just moving the truck around cause I was still working on a few things but as soon as I put it on the road I have hell with it

peow130

fuel filter?
jets too rich?

wannagetrdone

fuel filter is new that was one of the first things i checked. as far as jets go according to the carb setup instructions im between 1.5 and two turns out so jets check out I think. I cant determine if I have a lean or rich issue.

wannagetrdone

Here is the instructions I followed



Before you start engine warmed up to normal operating temp and choke disengaged:

Base line Settings

Idle Speed Screw 1 to 1 1/2 turns (closer to 1 but no more than 1 1/2 this is very important engine might not like it let it lope if you have to)

Mixture Screw 2 turns out



SET UP ADJUSTMENTS

Start set up by confirming carb base line settings. Do not depend on the factory delivered settings. Check them before the carb is installed.

All settings are done with choke disengaged or warmed up so that the choke is fully opened and disengaged. This is done on automatic choke carburetors by first opening the choke butterfly by hand and inserting a wood block or wedge of some kind to hold open while the linkage is cycled (linkage operated through its full movement ) to clear the choke cam. (You will hear a metallic click as the cam is released. You can check the fast Idle screw under the choke assembly to confirm that it is not in contact with the choke fast idle cam.)

Set the Idle stop screw (speed screw see above photo) by backing out the Idle speed screw until it is not in contact with the throttle stop lever. Cycle the linkage again to be sure that the linkage comes to close without any assistance. (Checking for linkage bind) Now bring screw back into contact with the lever and continue to open or screwing in 1 turn no more than 11/2 turns.

Set the mixture screw (see above photo) by first screwing in until the screw stops, bottoms out. DO NOT FORCE OR BIND AS THIS WILL CAUSE DAMAGE TO THE SCREW AND IT’S SEAT IN THE BODY OF CARBURETOR. Back out the screw 2 full turns.



TUNING

1. BE SURE TO FOLLOW THE NEXT INSTRUCTIONS IN THE PROPER SEQUENCE, DEVIATION WILL CAUSE THE CARBURETOR TO NOT FUNCTION TO ITS IDEAL SPECIFICATIONS AND MAY NOT PROVIDE THE PERFORMANCE AND FUEL ECONOMY AS DESIGNED.
2. Start the engine, the engine will run very slowly more like a tractor. As long as the engine stays running idle speed is not important at this point.
3. The first thing to do is not set up the idle speed, but to set the Idle mixture screw to lean best idle setting. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). The engine should pick up speed and begin to smooth out. Back out ½ turn more, or until the screw does nothing or runs worse then turn back to the point where it ran its best.
4. Use your ear, not a scope or tuning instruments at this point. You want to tune the engine by sound. Adjust to best, fastest and smoothest running point.
5. Now that the mixture screw is at its best running location, you can adjust the Idle speed the screw. The screw will be sensitive and should only take ¼ to ½ turns to achieve the idle speed you like.
6. Check and set idle to your driving preference. Put the car in gear and apply slight load, (AC on) and set the Idle as you like it. Don’t set it too high, as this will cause causes excessive clutch and brake wear. The Idle only needs to be 7 to 900 RPM with light load or AC on.
7. Recheck timing and vacuum hook ups. Recheck mixture screw to lean best idle again. If all is still best and smoothest idle then confirm and note the final settings.
8. To confirm settings with the engine running. Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies. If Idle Mixture screws are with in ½ turn of base line setting then all is well and have fun. Also check the speed screw and note how many total turns from initial contact. You may have opened (turned in) the speed screw. Your final setting should be under 2 full turns. Reset the screws (back in) to the best final settings (Per your notes) and go on a test drive and have fun. If the settings are other than described then you may want to recalibrate the Idle circuit (low speed circuit) to your engines needs. This is done by following the rule of thumb BELOW.



Simple Rules for low speed calibration

If the mixture screw is more than 2 1/2 turns out turns then the Idle jet is too lean (too Small). When the mixture screw is less than 11/2 then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 11/2 turns. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change. At times it may appear to be showing signs of richness or flooding it is really a lean condition. See pictures and notes in the tech 2 article supplied in the kit instructions, view and please understand the need to keep throttle plate as near to closed as possible so as not to prematurely expose the transition holes. This is what causes the visible rich condition, and confirms the need to increase the jet size. JET KITS are available if needed.

EXAMPLE With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from bottom, indicates the need for a larger Idle jet. Achieving the best idle at under 2 turns indicates the need for a smaller idle jet.

xxxtreme22r

You might be right, however,

The weber carb instructions specifically tell you to block that return line off. And also recommend the fuel pressure be set at 3-4PSI. Probably because of that very reason.

He is using an electric fuel pump not the OEM mechanical. So so check vavle it in since it's an inline fuel pump.

Weber says flow rate is more important than PSI. This is why they want the return line blocked off because you can have a momentary lapse of flowrate to the carb when the OEM fuel system is bypassing the carb sending the needed fuel to the tank instead of supplying the carb.

Usually a sign of this happening is if your off the throttle somwhat (float bowl full & fuel returning to tank) and then you hit the gas to half or full throttle, the truck then hesitates somewhat till the fuel pump has the chance to catch up.

This also happens to be a sign that the fuel jets are too small as well though.

If you hook up a fuel pressure gauge to a factory mech fuel pump, you can sit there and watch the PSI fluctuate by as much as 2-3 psi up and down. With the return blocked it results is a much more steady PSI.

wannagetrdone

well Im still having the same issue with the return blocked off. I think Im gonna go ahead and order a weber 38/38 and hopefully cure the problem if someone wants a weber 34/34 carb hit me up ill let her go pretty cheap. It might work good for someone who has a stock engine but im assuming mine with the hedder, cam, and intake may be a lil much.

xxxtreme22r

no problems like this with my 32/36 with header, cam etc, stock intake though.