1969 FJ40 Idles High and Misfires

[SlimerP98]

Just suck on that valve. You should hear or feel a valve open and let air through. It's a 1 way valve. It lets air run to the vacuum off the carb plate or intake but not the other way. If you plugged the other side of the hose coming from the engine then get ready for side plate and oil pan leaks. Put the new valve on with new hose and good clamps and see if it fixes your problem. I

Also, I did a comparison of the old valve and the new one, the old valve opened right up with barely any suction. The new one had a decent amount of resistance. The old one had better flavor though

 

[SlimerP98]

After some thought, I figured I could come up with a way to redneck engineer my way to a temporary solution. What I came up with was using a 1/4 in pipe thread nipple going to a 1/4 in - 3/8 in reducer. I had to drill out the 3/8 side to ~3/4 to get the grommet to fit well with the pcv valve in it. Now she runs almost perfectly! A very very slight misfire but I’ll fix that eventually. This is a temporary solution, I have the right pcv valve on the way (I think) but if not, I’ll make it nicer.

 

[sggoat]

So after giving it some thought, I decided to mess with the choke while it was running to see what would happen. When I close the choke almost all the way, it runs almost perfectly (although the RPMs, the misfire goes away). I then tried to adjust the idle mixture screw some more to see if maybe that was super out of adjustment, but it did not seem to change anything similar to how the choke being closed does. I am guessing that this means that I am getting too way much air and not enough gas, so maybe I have the wrong jets in it? I am at sea level and the carb itself came from Norcal, maybe that's contributing? I'm going to wait for it to cool down and look into that. I also tested the idle solenoid and I heard a good click when I hooked it up with the key in, the truck also died when I disconnected it when it was idling.

Vacuum sounds pretty good. (is the vac steady?, or does it wobble a little down when idling?) Misfire is sometimes related to the electronics--not fuel.--if it won't idle right unless the choke is on-indicates the carb emulsion tube(s) are restricted.(if Mark rebuilt, I would not suspect that)--but trash from somewhere else can get in there after the rebuilt unit was installed----
If the misfire is occurring at a regular interval-and the vac dips regularly,(even just an inch or so) go hold your hand on the exhaust pipe(do this when first starting from cold so the exhaust isn't too hot yet)--if your hand gets sucked back into the pipe when it 'misses', you have a valve issue(exhaust)--maybe just a valve adjustment-easy enough to run a compression check to see what the numbers are(and which cylinder it is) All should be in the 125+ range--hope this helps--

 

[SlimerP98]

Vacuum sounds pretty good. (is the vac steady?, or does it wobble a little down when idling?) Misfire is sometimes related to the electronics--not fuel.--if it won't idle right unless the choke is on-indicates the carb emulsion tube(s) are restricted.(if Mark rebuilt, I would not suspect that)--but trash from somewhere else can get in there after the rebuilt unit was installed----
If the misfire is occurring at a regular interval-and the vac dips regularly,(even just an inch or so) go hold your hand on the exhaust pipe(do this when first starting from cold so the exhaust isn't too hot yet)--if your hand gets sucked back into the pipe when it 'misses', you have a valve issue(exhaust)--maybe just a valve adjustment-easy enough to run a compression check to see what the numbers are(and which cylinder it is) All should be in the 125+ range--hope this helps--

It idles just about perfectly now, just with a very small misfire. The vacuum is very steady. When I first got it I did check the compression of each cylinder and they were all ok if I remember right. I will say though that the wiring on this thing is terrible so there could be something not quite right there. The valves do need to be adjusted as well, they tick pretty bad.

 

[sggoat]

That sounds great. You've Made some sig progress. If the vac gauge is steady, the valves are real close. esp if the ticking gets quieter when the engine gets to Op temp----what do the plugs look like?--all same color?

That hose going into the carb base has a clamp that does not appear to be tight---(wouldn't cause the misfire)

 

[SlimerP98]

That sounds great. You've Made some sig progress. If the vac gauge is steady, the valves are real close. esp if the ticking gets quieter when the engine gets to Op temp----what do the plugs look like?--all same color?

That hose going into the carb base has a clamp that does not appear to be tight---(wouldn't cause the misfire)

I tightened it way down after I took that picture, it's good now for sure. The ticking does not go away when it gets to operating temp, I attempted to adjust them a while ago but the car was warm and I was impatient so that's what I get lol. I haven't looked at the plugs yet, I definitely will next time I work on it.

 

[Green Bean]

Not sure if the pipe threads are right. Someone who knows far more than me, may chime in here but I was under the impression (perhaps mistakenly so) that Toyota uses BSPT (British Standard Pipe Thread) for its fittings. The threads are very close to NPT fittings but not exact. They make BSPT to NPT adapters. McMaster-Carr sells them.
Best wishes with your project.

 

[SlimerP98]

Not sure if the pipe threads are right. Someone who knows far more than me, may chime in here but I was under the impression (perhaps mistakenly so) that Toyota uses BSPT (British Standard Pipe Thread) for its fittings. The threads are very close to NPT fittings but not exact. They make BSPT to NPT adapters. McMaster-Carr sells them.
Best wishes with your project.

Interesting! I had no idea about that. It seems to be working, but I will definitely look for another adaptor then, thanks!

 

[SlimerP98]

So now I have the right accelerator cable hooked up to the carb (thanks for pointing that out @MDH33 !) and realized I need a return spring and a bracket. The bracket is no issue, but I cannot seem to locate a spring, does anyone have an idea of what specifications the spring should be? I also got a used PCV valve of the right style from another user for the price of shipping, but I noticed that it seems that the airflow path is opposite of what it should be I think, when I suck on it, it stops the flow.

 

[MDH33]

Good progress.

Here's a pic of the bracket and return spring. The spring isnt anything special. I bet you can find something at a local hardware store that's the approx length and tension.

 

[EWheeler]

So now I have the right accelerator cable hooked up to the carb (thanks for pointing that out @MDH33 !) and realized I need a return spring and a bracket. The bracket is no issue, but I cannot seem to locate a spring, does anyone have an idea of what specifications the spring should be? I also got a used PCV valve of the right style from another user for the price of shipping, but I noticed that it seems that the airflow path is opposite of what it should be I think, when I suck on it, it stops the flow.

I know Mark A has reproduction brackets available, and ToyotaMatt has repop return springs if you don't want to go hunting.

057-40ar

Catalogue Page 9

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www.marksoffroad.net

NEW J.I.S. GOLD CAD YELLOW ZINC PLATED F , F1.5 , 2F 3F CARB 20R 22R Carb ENGINE CARBURETOR Carb THROTTLE Linkage Return Spring Call Out # 78141A Part # 90506-12034 FITS ALL Gasoline TOYOTA Carburetors 1962-1992 GLOBALLY - VintageTEqParts.com

- FITS ALL Gasoline TOYOTA Carburetors 1962-1992 GLOBALLY - NEW GOLD CAD YELLOW ZINC CHROMATE PLATED F1.5 , 2F 3F Carb...

vintageteqparts.com

 

[SlimerP98]

Yeah, I was gonna go through mark for the bracket I was pretty sure. If the spring is just something pretty standard and easy to find then ill just go to the hardware store.