One idle mixture screw does nothing

[aaronmichorn]

So one of my idle mixture screws does not change the idle at all, and the other side kills the engine when it is screwed in too far. How do I go about cleaning out that side. So I guess nothing is coming out of that side. This is a new carb that sat with fuel in it for about 5 years.

It also starts to cut out around 3500 rpm's

Should I spray some carb cleaner into that idle screw hole and let it sit for a while and see if that fixes it? Seafoam? Hose the whole thing with carb cleaner?

 

[70_Steve]

What kinda carb? Yeah, removing the idle mixture screw and spraying carb cleaner might help. Try it a couple times in a row, letting it sit for a minute or two inbetween. Can't hurt!!!

 

[byson1]

If you spray it through that port try to block the outlet into the carb. throttle body. The idle screw adjusts the airflow going into the throttle body and at the same time pulls fuel from the float bowl through some very small channels. If you can get some pressure through these channels they might clear out-assuming that's the problem. Be sure the adjusting needle is in good shape too because if it's damaged on the end it will never adjust right. All it takes is one hard twist too tight to damage it. Quite honestly, if it's been sitting for 5 years and had feue left in it, then it's probably due for a good cleaning. MC2100-correct?

 

[aaronmichorn]

New Edelbrock 600 cfm. It was on, and the box was in the back of the truck when I bought it, so I figured it couldn't have too many miles on it. But then I started working on the truck and here it is almost six years later, and I am just getting it running again.

Someone suggested PB Blaster in the hole? Good idea or bad?

 

[70_Steve]

Someone suggested PB Blaster in the hole? Good idea or bad?

I don't think it would hurt, but I think a good carb cleaner would do a better job.

Interesting... My bronco had an almost new Carter carb on it when I bought it, with the Edelbrock triangular foam air cleaner for hood clearance. When I got to looking at things, I noticed a bunch of burned air cleaner foam all down inside the carb, like it had backfired through the carb and caught the air filter element on fire. So, I rebuilt the almost brand new carb, and found a bunch more burned foam inside the float bowls. Then I started working on the Bronco, and five years later, when I finally got it running again, I had to rebuild the carb again. The good news is that the rebuild kits are pretty cheap, and this has to be one of the easiest carbs ever to rebuild!

 

[aaronmichorn]

I had the same triangle foam filter on mine when I bought it. Hope I cna clean it up with some spray.

 

[aaronmichorn]

Here's some more background - new motor, new fuel tank and lines new filter.

just rebuilt the carb today, and still the same problem. Drivers side idle screw does nothing.

It surges and jumps when it it at half throttle

At full throttle it bogs and you can hear the secondaries open up, but nothing happens - no more power.

Checked the new fuel filter, and it's clean.

Any ideas

 

[wildbill]

If you have one of the triangle fome typ give it to someone you dont like (chev ect) and get a goos one that will work and not let crap into the carb. You mite try a good K&N have worked good for me over the years good luck.%) %) %) Bill ;D

 

[aaronmichorn]

GOt rid of the triangle one about a month ago. It looks like only one side of the carb is getting gas. I just totally rebuilt it this morning. When I looked down the carb and hit the gas, only one jet was spraying gas. The side where the idle screw isn't working did not jet any fuel. How does the fule system work.

Am I missing something here?

 

[70_Steve]

When I looked down the carb and hit the gas, only one jet was spraying gas. The side where the idle screw isn't working did not jet any fuel. How does the fule system work.

Am I missing something here?

The jet you see spraying gas is from the accelerator pump. One pump, one fuel passage, and a twin nozzle. Take off the nozzle (taking care not to drop it down inside the carb) and clean the other nozzle.

Here's a link to everything you ever wanted to know about your carb.
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf