I finally went to the Smog Referee again to have my 12/78 Cal spec FJ40 tested. After a long hassle, the guy finally put it on the dyno and said I failed because my CO% was too high and that was caused by the carb running rich.

Smog Test Results:

15mph
%CO2 = 13.1
%O2 = 1.2
HC = 54 (max = 196)
CO% = 1.75 (max = 1.59) FAILED
NO = 444 (max = 1507)

25mph
%CO2 = 12.9
%O2 = 1.3
HC = 63 (max = 161)
CO% = 1.86 (max = 1.359) FAILED
NO = 452 (max = 1367)

So, how easy is this to fix? Is it just a matter of tweaking the mixture screw and idle screw? Rebuild the carb? Check for dripping jets?

Any help is greatly appreciated (I know 2 stokes, not 4 storkes) :D

High CO is a rich condition.
Lean out the mixture, by either adjusting mixture and idle screws, or installing smaller jets.
Retarding the timing a bit also helps.
You are really close, I would probably tweak the mixture a bit.
HTH

You are close, so it could be something as simple as a clogged air filter or the choke not opening all the way. Also try spraying the entire inside of the carb with cleaner, revving it to 2,000 and hand choking it until it stalls to try to clean out the air correction and slow jets. If it still won't pass, it is rebuild time.

I will see what I can do this weekend. The air filter is new, but I will check the choke. I also have a rebuild kit, but there are so many parts in there. :D I am hoping I can just tweak the mixture screw to get it to pass.

I will see what I can do this weekend. I am hoping I can just tweak the mixture screw to get it to pass.

It is not likely that adusting the idle mix will have any effect, because it is failing at speeds above idle, where there is little contribution from the idle circuit. If you rebuild it, videotape the disassembly and take note about what goes where. An amazing number of parts can go in more than 1 way and only 1 is right. Clean with cab dip, wash thoroughly and blow out all the tiny holes to make sure that they are open.
Good luck.

Thanks....I am going to wait for the 3 day weekend to do this.

Update - carb rebuild 9/5/2004

The only carb rebuild kit I could find was from Borg Warner # 10566. This kit looks like a complete kit for carbs from 75-81 according to the parts guys. It comes with 4 base gaskets, bowl gaskets, jet gaskets, nozzle gaskets, float window o-ring, fuel solenoid o-ring, an accelerator pump and boot, 2 different sizes of BB's (3 small 3.16mm and 1 large 3.94mm), needle and seat assy, and a few other gaskets and sealing washers.

The carb rebuilt went fairly easy except for the BBs. I took out the accelerator pump check valve retaining spring and BB. That was a mistake!!! Getting the retaining spring back in was a nightmare for me. It took way too long, but I eventually got it back in. Does anyone have any tricks for this?

My carb only had 2 BBs which were both the same size ~ 3.16mm for the accelerator pump plunger/check valve and pump outlet check valve. However, the rebuild instructions and 2F repair manual state the larger BB goes in the pump outlet check valve. So I put the 3.94mm BB into the pump outlet check valve and the 3.16mm BB into the pump plunger check valve.

Is this correct???


I also found out that my float was set to 10mm instead of the recommend 7.5mm so I readjusted the float height to 7.5mm. Tech note => 19/46" drill bit is 7.54mm which is what I used to set the float height

Other misc bits of info.....
power valve jet - 070
primary slow jet - 070
secondary slow jet - 070
primary main jet - 124 (brass)
secondary main jet - 171 (brass)
primary and secondary nozzle "1" with two rings (identical)

The phenolic block had the bonded gasket on both sides + another gasket on each side. I took a razor blade and tired to remove the extra gasket and I found the bonded gasket to have some nicks in it. So I clamped the phenolic block in the Bridgeport and took a fly cutter and removed the bonded gasket from each side. I think I took off about 0.035 to remove each bonded gasket......it is so nice to have a mill at home. :D

Today I hope to find some time finish putting the carb back together, install it and test it out. I hope all goes well.

It sounds about right. I forgot to mention not to take the butterflies off the shafts as it is a PITA since the screws are staked. Don't forget to blow out the tiny holes (air correction jets) in the top cover (aka air horn).

Update - 9/6/2004

I got carb back together and installed. I still need to double check the linkage to make sure I have all the set screws set correctly and that there is no binding. It fired right up and ran fairly well. I set the idle mix and adjusted idle like the book says and it seems to run smooth (I did not take it out for a test drive.........had a few). The float was low and the gas level was at the bottom of the window. I guess I need to remove the top of the carb and reset the float height.

It seems curious that you set the float at 7.5mm and it still showed low. I usually set my closer to 10 and they show in the middle. Maybe you should check to see if the float arm is parallel to the float.

I have a 77 fj40 and failed the test about 4 times before I passed. Mine ran to rich as well so in order to pass I took out both jets and dripped some sawder in to, two extra jets. Then drilled out with a small needle. Cruiser ran like shit but guy at the shop said it smogged better than a new car. Now i keep the jets in a bag and will switch in when it comes smog time again. Hope this helps. :flipoff2: :D :p