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  #31  
Old 09-17-2011, 04:06 PM
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subzali subzali is offline
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Originally Posted by PhatFJ View Post
1975 FJ-40


Hey Matt, thanks for this great thread!! I am trying to learn the STOCK carb setup as well and this got me to go out and check my setup. I verified all the linkages and vacuum lines, put the paper clip on the front diaphragm linkage and took it for a drive, not only did it NOT move but the motor seems to decelerate when I floor it. So, I pulled the vacuum assembly and verified that it does work, blew into the port feeding the vacuum module and could hear it blowing into the carb body which I can only assume, this is where the vacuum is being drawn from (funny, my emission control repair manual does not even mention this module nor the secondary acceleration). I am at a loss as to why the secondary is not opening, everything seems to be correct. I had Kim push the throttle to the floor while I verified that the linkage IS free to move and open the secondary venturi, could it be that I am not drawing enough vacuum to open it? if so, why? it seems to drive just fine as long as I am not asking for full throttle..
That seems weird Brian. In fact, I was crossing my fingers that my only problem would be the bracket on the firewall. I wasn't sure what to do if I fixed that and it still didn't work. The operation of the secondary isn't really covered in your Emissions manual, but the Engine FSM shows a cutaway schematic and shows how to disassemble the secondary diaphragm housing. The Haynes manual shows the cutaway schematic as well. The source of vacuum is just downstream of the venturis, and there appears to be an orifice in that location, so theoretically if the throttle plates are open, drawing air through the venturis and you are giving yourself enough duration to overcome the effect of the orifice, it should operate. The fact that you are experiencing a stumble or hesitation at WOT could be the culprit though. Have you done all of your basic checks? Vacuum leaks (vacuum readings), timing, valve adjustment, accelerator pump functioning properly? 1975 Cruisers will also have the auxiliary accelerator pump (AAP), so you will need to verify that that is working properly as well.

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Originally Posted by PhatFJ View Post
One other thing, while checking the vacuum lines I pulled the throttle positioner diaphragm line and pulled vacuum on it, it does move but it does not hold vacuum at all with the linkages returning to their normal position almost immediately after drawing vacuum, again, my manual does not go into the operation of this unit only the complete circuit, is this supposed to hold vacuum and keep the linkage in position as long as vacuum is being applied?

as always, thanks for the help!!!

Brian
Looking at the Emissions FSM to verify, I believe the TP diaphragm should hold its position while vacuum is being applied, because at idle it is the vacuum that keeps the TP diaphragm pulled away from the throttles, allowing them to close fully and allowing your idle circuit to function properly and for you to make adjustments to your carb properly. Sounds like you might need to find another TP diaphragm (I don't think they are rebuildable), or test your vacuum-producing equipment to make sure it's not leaking, giving you false results. Actually, the best check would be to let the engine idle and see if the TP diaphragm remains retracted.
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Last edited by subzali; 09-17-2011 at 07:32 PM.
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  #32  
Old 09-17-2011, 06:00 PM
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Rezarf Rezarf is offline
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Wow Matt, thanks for the pics bro, that really helps. I am going to see what I see later tonight if I can get my to stomp the pedal a few times.
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  #33  
Old 09-17-2011, 08:36 PM
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Turns out my TP diaphragm doesn't work either. I think. EDIT: It's not my TP diaphragm, but maybe the VSV. I need to look into it more.
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"Stay the Trail," "Tread Lightly," and "Leave No Trace" ethics
TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD

Last edited by subzali; 09-19-2011 at 07:04 AM.
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  #34  
Old 09-18-2011, 07:21 AM
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Thanks for the reply Matt!! I have done a complete tune on the 2F and like I say it does run really well as long as I am not asking it to produce power at full throttle, even the idle control seems to work well, when I come to a stop the idle is noticeably higher and I can hear it step down, so I am not convinced that the Throttle Positioner is not working properly. The PO had the carb rebuilt and I am not sure it was done properly and I think it was done with a low end rebuild kit as he did give me the box. This being said, I think I am going to remove the carb and totally go through it by the book. Any advise on rebuild kits? I did look at the kit that SOR sells, I do not know if there is the same kit available locally or not.. One other thing on the Throttle Positioner, the 2F manual does say to "connect hose to choke breaker diaphragm (throttle positioner) and suck the hose with mouth. The diaphragm should move. If not, replace it". Well if yours is like mine, it does move but it just does not stay in the position.. Don't know, my choke works well and idle seems to work well

Thanks again bro!!
By the way GREAT PICS!!! I don't know how you get some of those shots, I could not get a camera in some of those positions..

Brian
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  #35  
Old 09-18-2011, 07:59 PM
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Keyster kits are pretty popular for carb rebuilds, but supposedly the Hygrade kit is better. You can buy either of them on ebay.

I have a pretty small camera I guess
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TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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  #36  
Old 09-18-2011, 08:03 PM
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Matt, my carb secondary is activated by a switch on the throttle when floored, and goes through the emissions computer that releases the vacuum. If you have yours freed of the computer, perhaps you aren't getting the vacuum you need when you need it...
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  #37  
Old 09-18-2011, 08:13 PM
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Interesting Kurt. Mine is definitely not controlled by the computer in any way, and wasn't designed to from the factory. Maybe it's a California emissions thing? I'll have to check yours out sometime.
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Matt Miller
"Stay the Trail," "Tread Lightly," and "Leave No Trace" ethics
TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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  #38  
Old 09-19-2011, 07:13 AM
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Quote:
Originally Posted by PhatFJ View Post
...Well if yours is like mine, it does move but it just does not stay in the position.. Don't know, my choke works well and idle seems to work well
Brian,

I just did the mouth-vacuum test on my TP diaphragm this morning. It pulls back and stays back as long as I keep the vacuum applied. But at idle it's not engaged like I think it should be. Maybe my VSV is not working. Hm.
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Matt Miller
"Stay the Trail," "Tread Lightly," and "Leave No Trace" ethics
TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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  #39  
Old 09-19-2011, 08:50 AM
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Quote:
Originally Posted by kurtnkegger View Post
Matt, my carb secondary is activated by a switch on the throttle when floored, and goes through the emissions computer that releases the vacuum. If you have yours freed of the computer, perhaps you aren't getting the vacuum you need when you need it...
Hey Kurt, looking at my emission control for 1975. The throttle position switch (at full throttle) activates the "power valve control system (2f engine only)", this does have the computer, vsv, red thermo s/w and vacuum surge tank as part of the same system.. I went through this system as well using a vac gauge and dmm, pulled the red thermo s/w and tested it with hot water on the stove.
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  #40  
Old 09-19-2011, 09:03 AM
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Quote:
Originally Posted by subzali View Post
Keyster kits are pretty popular for carb rebuilds, but supposedly the Hygrade kit is better. You can buy either of them on ebay.

I have a pretty small camera I guess
Thanks Matt, I pulled the carb yesterday to look it over. I noticed that the spring at the end of the secondary shaft was not fully wrapped to the stop, thus not applying enough tension to the secondary TV shaft. I fixed this, took it for a drive and it seems to be better but still not the power I think it should have. I will do another paper clip test today. Hey, looking at the 2f manual this morning I noticed that there are 2 springs in the picture of the secondary diaphragm, I am curious if the one in mine is to heavy, not allowing the diaphragm to retract I did look for the Hygrade 791b kit and could only fine it at Woody's $40.00 + $11.00 shipping Oh, I also pulled one of the carb mounting studs out of the manifold so I got to do a helicoil repair yesterday as well.. Are we having fun yet???
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