2f Aisin carb secondary question. (pics) (1 Viewer)

[Bennett]

Got 76 fj40 with a stock 2f and a carb that was originally rebuilt by a guy at a toy dealership in Colorado.
The cruiser runs great but I don't know how the secondary works.
I took the carb off to replace the accelerator pump and reset the float.
I was meticulous with the takeoff and took pics.
What I don't get is the secondary plenum is sooted up( maybe running rich) but I don't see how it works mechanically.
Is it run by the vacuum and diaphram or though the linkage?

Heres a picture... I went to sor site but I need a non-exploded view as how it sits in stock form. Any one got a pic?
Anyone got a link that shows how the setup works.
opinions appreciated

top two pics are of the diaphram and the second is of the linkage.

 

[alan m]

It should be actuated by both methods;
Vacuum under all normal conditions, and linkage when you are accelerating with the pedal to the floor.
If you operate the throttle you should see the secondary open up at some point, the manual has instructions on how and where the secondary shoud open.
Hope this helps
Alan

 

[Bennett]

well that helps a little knowing it takes both...

My secondary does not open as I look down the carb on full throttle ( engine off)

1. is there a test for the diaphram to see if its operating?

2. Which manual-- I have a Haynes somehere if I can find it

 

[Pin_Head]

If you want to check if the vacuum actuator is working, put a paper clip on the link rod so it is touching the aluminum canister and then take it out and put the pedal to the metal going up hill in 4th gear. Then stop and see how far the clip has moved down the rod. It moves about 3/4 inch to fully open the secondary.

 

[Bennett]

Just going through the Haynes manual and I don't see the mechanical aspect of it?

are you sure there are mechanical connections for the secondary?
As I read it NO...?

"The 2 barrel carburetor on the 2f engine has a different method of operation for the secondary vale but is otherwise generally similar to the early F type. The secondary valve on the 2F is operated by a diaphragm mechanism which senses the venturi throat pressure drop which occurs at high primary barrel airflow's, and causes the secondary valve to open by an amount proportional to this pressure drop.
USA carburetors also incorporate an auxiliary acceleration pump which provides an additional rich mixture during heavy acceleration."

I appreciate the bb help btw..

 

[alan m]

The chapter starts on page 48 for my manual, should be about the same for yours, the linkage diagram and description of the primary and secondary linkage stops is on page 58.
It looks to me from your photos that you are missing a part of the linkage. There should be a link bar from th main throttle crank plate to the arm of the secondary. The crank plate acts like a cam preventing the secondary plenum from opening until the primary is opened to the correct amount.
Check the parts diagram for the carb in your manual.
Good Luck
Alan

 

[subzali]

The 2 barrel carb for the F engine was mechanically actuated - you could feel a "kick" if you hit the throttle. The 2 barrel carb for the 2F engine is vacuum actuated with the diaphragm. Try Pin_Head's suggestion. If that doesn't work I'm not exactly sure how to remedy the situation, as I'm in the boat of apparently not having a secondary (according to the paper clip method).

The AAP only showed up on '75 model year Cruiser carbs AFAIK.

 

[alan m]

My mistake, sorry for the bad info. I looked at the diagram again and can now see that I was looking at the carb for the F engine and not the 2F.
I owe you one.
Best Regards
Alan

 

[Bennett]

yeah I just checked it out...

here is what I have and it loosk complete....

Does not open ( engine off) when pedal depress

will check diaphragm method paper clip tomarrow -

thanks for the help guys

 

[ducktapeguy]

The secondary is vacuum actuated, but it's mechanically limited by the primary throttle shaft. The primary needs to be wide open before it will allow the secondary to open, but you need to have vacuum first before it will open.

In the second picture you can see that funky shaped cam thingy that blocks the secondary from opening until the primary is all the way open. Visually, you can see if it works by pulling up on the vacuum rod connected to the diaphragm and holding it up to simulate the vacuum on the diapragm. This will wind the little coil spring lever on the shaft. Then when you open the primary throttle the spring will allow the secondary to open. Kinda hard to describe, but play around with it and you'll see it work. If that spring was put on wrong it will cause weird things to happen.

I spent a long time troubleshooting mine and tracing vacuum leaks to try and figure out why it didn't work, eventually when I swapped carbs it started working a little bit.

 

[Bennett]

thanks so much... will check these things today

BTW-
In the first pic ..what is the electrical connection ( sensor ? )

just to the left of the vac actuator- you can see the spade connection right below the left jet bolt access and

pointing toward camera. My manual does not show that and it runs fine without it hooked up. Maybe a carb fan sensor?
76' did not come with a carb fan as I recall.

opniions appreciated

 

[Bennett]

thanks so much... will check these things today

BTW-
In the first pic ..what is the electrical connection ( sensor ? )

just to the left of the vac actuator- you can see the spade connection just below the left jet access bolt

pointing toward camera. My manual does not show that and it runs fine without it hooked up. Maybe a carb fan sensor?
76 did not come with a carb fan as I recall.

opinions appreciated

 

[duffontap]

BTW-
In the first pic ..what is the electrical connection ( sensor ? )

I've heard that that is a temperature sensor. I have a '77 parts rig that does have the carb fan, but I'm really not sure about the '76, other than to say, my late '76 (September date of manufacture) is a '77 in most respects.

Good luck with your carb!

 

[subzali]

8/76 is the beginning of the '77 model year.

You can check SOR for diagrams and pictures of carbs - 1976 Federal for example:
Specter Off-Road Land Cruiser Parts - Page 042 Land Cruiser Carburetion

'76 does have a thermo sensor at the carb for the emissions control computer - I don't think it has anything to do with the carb cooling fan (which came on '76 California emissions models, but wasn't standard until '78 or '79).

 

[Pin_Head]

The carb base sender is a temperature sensor that lets the emissions computer wait until the carb heats up to run the EGR system.

 

[Erik Swenson]

Man these are some old posts? Where have I been! I'm just getting started with this Aisan carb stuff. I too noticed that the second barrel did nothing when I tried to tune my carb today. Dry like bone...….just the barrel closer to the manifold side was active. I still couldn't really get the tuning done.....