View Full Version : Carb help
05-30-2011, 05:20 PM
Greetings:I'm new to the forum. Looks like some knowledgeable folks around here. Looking for some carburetor advice. I have a fairly stock 76 FJ40 in good condition. For the past few months it has been my daily driver since my wife's car is FUBAR and she is driving my 06 TLC. Last year I had some trouble getting the beast to start so I swapped in a rebuilt card from SOR, that didn't help so I took it to my mechanic and he found some electrical trouble. So now it starts easily and runs smoothly with decent power, but it won't idle. I have to constantly play with the choke and keep the RPMs at 1000+ or it will stall. Some times even with the choke out 3/4" and the idle at 1000 it will stall when I push the clutch in as I stop. My mechanic has played with it and sometimes it works for a while then back to the same problem. The fuel pump is original, but seems to be OK. We cleaned the gas tank out and recoated the inside. All the filters have been changed. I do have a DUI electronic ignition/distributor installed and a Mean Green high output alternator, if that makes any difference. I also had a cracked exhaust manifold, so I replaced it with a header a few years ago and my mechanic found a vacuum leak which he fixed. I could throw the old carb back on, I still have it and it might still be OK.
I'm sorry this is so long, but I appreciate any help you guys can give me.
05-31-2011, 02:23 AM
You might try checking that pesky low idle circuit wire. It is connected to the top back of the carb and it has a wire that wraps around to the front of the carb, then to a connector coming from the wire loom. This wire is often wrapped in a white nylon weaved sleeve to protect it from the high manifold temperature. If that wire and connection is not good, it will cause it to stall at low idle just like yours is. Even though it looked OK visually on mine, when I put in new connectors, it fixed my low idle stalling problem.
05-31-2011, 06:17 AM
Sascha has good advice. Check again for any other vacuum leaks e.g. brake booster hose, and pop the top of the carb off and check the bowl to see if there is anything floating in there.
Could you please post up a picture of your setup? There's a couple hose connections that definitely need to be correct on a '76 for there to be no vacuum leak or other problems.
Have you dialed the adjustment in using the lean drop method like in the factory service manual (FSM)? If you don't have an FSM, it's a great tool to have :thumb:
05-31-2011, 07:38 AM
The issue description would indicate a vacuum leak and/or problem(s) with the idle circuit. With the idle turned up to the 1k+ rpm range, the carb is moving some fuel from the primary circuit. Of course it could be something else, but the symptoms warrant taking a close look at these items.
You indicate the mechanic already found and corrected vacuum leaks. I would recommend that you follow up and check for leak(s) yourself. First, you wan to get familiar with what a vacuum leak "sounds like" when you find it. So, with the engine running, spritz a bit of brake cleaner/carb cleaner right at the opening of your air intake, what a few seconds and you will hear the RPMs change. Once you know what you are looking for, continue to spritz and listen; where the carb mates to the intake manifold, the intake manifold mates to the block, all vacuum hose connections from the manifold to smog equipment and the brake booster. Finally, disconnect the vacuum hose from the brake booster and plug the end of it. Take your time as you do these checks, be very methodical - you want to find any leaks and be confident the check was thorough. :D
Sascha, my son and Pete (in Longmont) are all situations that I have first hand experience where the issue of power to the idle solenoid was intermittent and in all three cases the wire visually looked ok. The idle solenoid receives power when the ignition switch is in the run position, as it receives power it pulls back a needle an opens the idle circuit for fuel to make its way into the carb's primary barrel.
It could be the idle solenoid is bad (it is unusual for them to fail) and not working. Test the idle solenoid by providing it power and listening for the click of the needle retracting. Do this test and if you hear the click then consider the idle solenoid good - for now.
If the idle solenoid is bad, test the one on your old carb and if it clicks - swap them. If the idle solenoid is good, then take a real close look at the wire that provides power to the solenoid.
Also, post up photos of your vacuum line connections. When installing the rebuilt carb, perhaps the connections got "messed up"; that is to say if you don't take detailed notes it is very easy to put something in the wrong place or even if you took good notes and put everything back where it was, it could have been in the wrong place to begin with:D. While I am not familiar with the 76 year connections, Subzali has done quite a bit of research and is correct about the lines needing to be right. A couple of years ago (at the 40s Only Run) Rui (from CO Springs) was having trouble with idle and we found the vacuum connection for his distributor was not connected correctly; after connecting it to ported vacuum his idle issues were resolved.
Finally, if none of the above steps find an issue - it is likely some crud made its way into the idle circuit and is intermittently clogging the circuit. I understand this is a rebuilt carb, but the crud could have been introduced via the fuel system.
Let us know what you find out after looking at the above items and we'll go from there. :thumb:
06-01-2011, 08:02 PM
Excellent! I knew I came to the right place. Let me try these suggestions and get back to you. The rig is with my mechanic right now getting a state inspection, but I will share these notes with him tomorrow. Between the two of us we might be able to sort it out. That is one complex carburetor. I miss my old 62 Ford Fairlane.
06-02-2011, 12:54 AM
I miss your 62 Ford Fairlane too. Now THOSE had a back seat worth partying in!
06-02-2011, 03:43 PM
Ah yes, many fond memories.
10-10-2011, 10:52 PM
I had some time to work on the old FJ this weekend and a friend of mine who happens to be an automotive engineer from Detroit was in town lending a hand. We discovered and corrected a few things. One was the timing was not correct and we adjusted that. Second there were some unusual connections in the vacuum lines, but no apparent leak. We redid the connections the right way, but Unfortunately we still have no idle. We also discovered that the idle adjustment screw was way out, I can only assume my mechanic was try to get the truck to idle that way. The interesting thing is even when the engine is sitting for awhile there is strong smell of gasoline coming from the carb and if you check the site glass on the side of the carb it is at the top when the engine is first shut down and then the level slowly drops. My friend, who admittedly is not a Toyota mechanic, felt that this was inappropriate and wonders if there is a leak somewhere. Anybody able to give me some insight on this? I'm going to take another look at the vacuum leak issue and post some photos of the vacuum hose connections.
10-11-2011, 06:33 AM
Sorry to hear you're still having trouble with your carb. Pictures will certainly help with some ideas of what the problem might be. How quickly does the level drop in the carb window? Eventually the fuel will evaporate out, but normally it can sit for a couple days without a noticeable drop in the level. Do you have a factory service manual or a Haynes manual available? Have you tried adjusting the idle using the "lean drop method"?
10-11-2011, 07:16 AM
... We also discovered that the idle adjustment screw was way out, I can only assume my mechanic was try to get the truck to idle that way. The interesting thing is even when the engine is sitting for awhile there is strong smell of gasoline coming from the carb and if you check the site glass on the side of the carb it is at the top when the engine is first shut down and then the level slowly drops....
Some pictures would be good, just to make sure we are understanding and giving you good advice; for example "the idle adjustment screw was way out" - the carb has a couple of idle adjustment screws and often people refer to the idle mixture screw as an idle adjustment screw.
The fuel level should be right in the middle of the site glass. A well tuned carb should have the fuel level remain steady.
10-13-2011, 12:16 PM
The high fuel in the site glass makes it sound like you have something going on in the carb. Probably a missing check ball or spring, or possibly a faulty float adjustment. It may not be idling because it has been adjusted to compensate for the unregulated fuel? If it were me, I would double check the idle solenoid and if that is ok, I would just jump in and pull the carb, open it up and start checking everything out. I've seen a lot of "rebuilt" carbs missing parts.
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