Carb help PLEASE!

[Robert LaDuke]

Hi All,
I've got a '78 FJ40 with a fresh Jim C carb. Newly rebuilt engine new fuel pump , filter and all fuel lines. I don't seem to be getting any action from my second barrel. When I romp on the gas in third nothing happens. Can't get her to go over 55mph. I checked the linkage and it is doing what it is supposed to. Diaphram is brand new. Any ideas?

I should add that she ran great when I first installed the carb.
Thanks for any help.

 

[Ming89FJ62]

Give Jim C a call - he's always been willing to help.

 

[65swb45]

Somebody else posted up a couple of weeks back a really cool way to check the secondary diaphram by slipping a paper clip directly underneath the diaphram that just has enough tension to stay on the shaft and driving around. If you open the hood afterwards and the paper clip has moved, then you will have your answer as to the secondary diaphram working.

If it ran fine when you first installed it, then contamination is also a possibility. If you are running stock steel lines, they are prone to collecting shellac over the years, breaks off slowly, when it feels like, and is past the factory fuel filter. Most rebuilders will not warranty dirt, but I wouldn't attempt to speak for Jim.

Run the test, then call him.

 

[Dave E]

I think my second barrel was not working on my carb as well. I think it was the cable legnth. I could never seem to get enough movement on the carb to open the secondary. Have some one step on the gas and watch to see if it opens.

My 02

Dave

 

[Landpimp]

I don't think you can look and see it opens when parked.

I think my second barrel was not working on my carb as well. I think it was the cable legnth. I could never seem to get enough movement on the carb to open the secondary. Have some one step on the gas and watch to see if it opens.

My 02

Dave

 

[Robert LaDuke]

Thanks for the ideas guys. I have tried the paper clip trick. It doesn't move, so I know the secondary isn't opening. I emailed Jim C about the problem and he said to check for something blocking the fuel. I had ruled this out because I replaced everything from the fuel filter to the carb including the steel lines and the pump.
I guess I should pull the carb apart just to be sure.

 

[65swb45]

Well, if the secondary isn't opening, you've got two choices: either the diaphram responsible for pulling the secondary throttle shaft isn't working, or it is not getting a vacuum signal because of problems inside the carb.

You can pull the two screws off that hold the diaphram to the carb body and pull the circlip that holds the bottom of the linkage to the throttle shaft. Once removed, you can push a rubber hose up against the vacuum port on the diaphram and, using any reliable vacuum source, test the diaphram. If it's working then you know that the diaphram isn't getting a good enough signal.

Also note, the two screws that hold the diaphram should come off nice and easy if the diaphram was removed during rebuilding. Stuck, frozen or stripped screws are a sign that the diaphram has not been removed.

Mark

 

[Robert LaDuke]

Thanks for the help Mark. I did what you suggested and tested the diaphram . It works with my vac pump attached. So I must not be getting vaccum from the carb. Is there an internal valve that controls this? I'm looking at the carb schematic in the factory manual , but not sure I understand it.