Have a stock fully smogged 2F that starts and drives fine and even idles as long as the choke is about 3/4 way out……however this is the weird part…..once the engine gets fully warmed up (hot) and while it is idling…..the engine will suddenly begin to rev up at very high rpm and if I push the choke back in (off) it idles back at normal and will do so without any choke. Once it cools back down the problem returns. I’ve seen other threads about a blown fuse affecting the fuel cutoff solenoid (ics) but fuses are all fine. It seems that maybe one of the vacuum switching valves (vsv) that plug into the head/water housing are suddenly ‘opening up’ or closing off’ causing the carb to dump more fuel …..has anyone else run into this problem? Any suggestions on what to test? Fuel pump is fine and is an in-line fuel filter. Thanks in advance.
Stock 79FJ40 …..starts and run with choke on but….
- Thread starter crewzerdog
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Skreddy
SILVER Star
Is the fuel solenoid clicking when you turn the key on and off?
The choke really shouldn’t be used for very long at all. Like full choke, start up, push choke in as you can to maintain stable high idle. By 2 minutes tops, my choke is all the way in.
Has it ever ran fine without the choke? Has any work been recently done? (If yes, I’d start there). Timing? Valves adjusted? Ignition component condition?
The choke really shouldn’t be used for very long at all. Like full choke, start up, push choke in as you can to maintain stable high idle. By 2 minutes tops, my choke is all the way in.
Has it ever ran fine without the choke? Has any work been recently done? (If yes, I’d start there). Timing? Valves adjusted? Ignition component condition?
Pull all electrical plugs apart and clean them. Use a qtip to apply a coat of dielectric grease to the contacts. Inspect the wires at the crimp connection - corrosion can crawl under the insulation and limit transmission of power. Disconnect the neg terminal at the battery, then clean all the contacts in the fuse box on the front and the back. Test the fuses, they can look good but actually be bad.
Hook up a vacuum gauge and see what it does. Put a big hemostat on the brake booster hose - does vacuum go up? I use a can of WD-40 with a pee tube to check for vacuum leaks. With the cold engine idling as steady as it can - quickly and lightly spray along the intake gasket surfaces and the carb section joints - if RPM's kick up - that's the spot where the vacuum leak is.
I have none of those things. Cold start with my Rochester carb. Turn key on - listen for the electric fuel to quit clicking. Step on the gas pedal to the floor - pull the choke all the way out - release gas pedal - engage the starter. It will light right up at fast idle, start pushing the choke in slowly. With the header its very cold blooded - my liquid heat riser helps a lot. After a few minutes I blip the gas pedal which releases the fast idle (that was set when the choke was pulled out with the gas pedal on the floor). Depending on how cold it is determines how long it needs some choke to run. I also have a curtain to block the lower 1/2 of the radiator so it will actually get warm with the 165 degree thermostat. I have 2 heaters. The rear one is like the size of a Subaru radiator.
Hook up a vacuum gauge and see what it does. Put a big hemostat on the brake booster hose - does vacuum go up? I use a can of WD-40 with a pee tube to check for vacuum leaks. With the cold engine idling as steady as it can - quickly and lightly spray along the intake gasket surfaces and the carb section joints - if RPM's kick up - that's the spot where the vacuum leak is.
I have none of those things. Cold start with my Rochester carb. Turn key on - listen for the electric fuel to quit clicking. Step on the gas pedal to the floor - pull the choke all the way out - release gas pedal - engage the starter. It will light right up at fast idle, start pushing the choke in slowly. With the header its very cold blooded - my liquid heat riser helps a lot. After a few minutes I blip the gas pedal which releases the fast idle (that was set when the choke was pulled out with the gas pedal on the floor). Depending on how cold it is determines how long it needs some choke to run. I also have a curtain to block the lower 1/2 of the radiator so it will actually get warm with the 165 degree thermostat. I have 2 heaters. The rear one is like the size of a Subaru radiator.
- Thread starter
- #4
I’m going to recheck the fuel solenoid…..it’s been 10 years but this was a complete frame off rebuild….every nut bolt etc removed and replaced…..garage kept and in pristine condition. That said, you made some good suggestions. I’ll run some of these down this next week.
Skreddy
SILVER Star
What is going on here?
I’m assuming you’re charging the battery or a battery tender is why there’s alligator clamps, but the circuit breakers? Looks like the positive lead is laying on one of the housings. I’ve also never seen cb’s attached directly to a battery like that. How are they even working if all on one bar?
That’s the Harbor Freight winch standard relay/breaker that is designed to bolt to the battery (obviously one could do more neatly if desired). It doesn't look as smashed up as mine, but mine gets moved to the car hauler trailer and dragged on the ground a few times.. oddly durable!
- Thread starter
- #9
Yep that is the winch electrical connection and yes I have a battery tender attached as well. I get checking all the normal vacuum leak locations like base of carb, intake manifold etc….had checked them all before and they are fine….(had previously had the manifolds machined as a mated pair) to me the odd part is how the engine will idle ‘ok’ with the choked pulled and then on a warm day when engine/truck has been driven awhile it will very suddenly rev high rpm and I can push in the choke and all is fine….it will purr like a kitchen and idle at normal low rpm. Seems like it is more related to all the spaghetti mess of vacuum lines going to one the vsv that cause the carb to suddenly “open up” and dump fuel but I’m certainly no expert on all the smog junk under the hood and how it affects the fuel delivery process. If I can’t track this down then thinking of doing a desmog and adding a Holley Sniper to the FJ40 and call it ‘done’. I kinda like the ICS/fuel solenoid angle.
I'm not sure why you keep saying you push the choke in after it has been running... Are you driving with the choke pulled out? please verify your process. If you are doing that to make it run good, the carb needs addressed. Also confirm idle solenoid is properly functioning or just replace it - it can be finicky. Also, the computer might need points re-soldered to motherboard inside. During unplugging/plugging back in they become damaged and your idle is controlled by that little black box (if equipped). Usually this does not cause racing, but the opposite like poor vacuum. If you are compensating by opening up the choke, then computer comes back online that could cause racing.
Also, verify the choke cable/attachment condition. Is it frayed, sticking. Is it good and responsive where it engages the arm that opens the choke?
Also, verify the choke cable/attachment condition. Is it frayed, sticking. Is it good and responsive where it engages the arm that opens the choke?
- Thread starter
- #11
Its standard on later model 1/79 US models…..carb images on SOR show the same ‘thingamajig”. I’m assuming this is part of the smog system required on later model US FJ40s. Not sure what it does…..vacuum lines come and go everywhere on the 1979 …there are a bunch of VTVs; BVSVs; check valves; ASVs; etc etc. I have the factory service manual for the 1979 emission control system but reading it makes your head hurt…..a lot.
- Thread starter
- #12
Sorry, let me clarify…..yes, I do have the choke out (engaged) to start, to idle and to drive around. Once the engine heats up is when the sudden increase in rpms occurs and I then push the choke in (disengage it) and it returns to standard idle. Also I have check the idle solenoid with the engine off….using some jumper wires and I do hear a consistent ‘click’ when the leads are touched to the battery. It’s cold and rainnng here today so I may recheck it with the engine running later in the week. Yes, this 1979 has the “computer” on the inside firewall. I have a ‘backup’ and may try to exchange to see if I have any change in conditions. Also I did a top side rebuild on the carb relatively recently (the accelerator pump plunger had dried out) so I did a clean/replace then. The entire carb was rebuilt a few years back. As you probably deduce the truck isn’t driven a lot. Choke cable….its actually a solid cable and it’s not sticking, frayed and the get full movement as it should. Thanks again for all the suggestions. Too bad Toyota had to put all this
on the engine back in the late 70s. I had an early model FJ40 back in college (won’t say how long ago that is 
) but it was super simple to work on….could almost sit on the fender and dangle your legs inside the fender wells there was so much room…..not the case of the 1979.
I refer to it as enough room to climb in the engine bay, shut the hood and work in the shade sort of room.
Yea the E'PU' is no friend to ICU engines that for sure. Taking lead out of gas - good plan. Then they forced MTBE as the additive - oh wait that ends up as a carcinogen in the drinking water, never mind. Lets burn our food - corn instead - that's the ticket. Then there's the diesel - lets burn piss with it while choking the engine with recycled exhaust.
I really like electric car/truck/bus fires so environmentally friendly that they are near impossible to put out and they re-light when you aren't looking.
Yea the E'PU' is no friend to ICU engines that for sure. Taking lead out of gas - good plan. Then they forced MTBE as the additive - oh wait that ends up as a carcinogen in the drinking water, never mind. Lets burn our food - corn instead - that's the ticket. Then there's the diesel - lets burn piss with it while choking the engine with recycled exhaust.
I really like electric car/truck/bus fires so environmentally friendly that they are near impossible to put out and they re-light when you aren't looking.
- Thread starter
- #14
Btw….i stumbled on another post about desmog and it turns out that ‘gold’ piece is called a “hot idle compensator”.
Skreddy
SILVER Star
If you are using your choke for longer than 1-2 minutes for initial warm up, you have issues. If you’re driving with your choke on at operating temp and it seems fine; you have issues.
Using a jumper to check the fuel cut solenoid ensures it works, but you need to verify it’s working with the key switch. If there’s a bad wire or something, you’re removing it by jumping so not a like for like test.
You probably have a vacuum leak, but if you’re running and driving with the choke on, there’s no point in diagnosing from here. Running to operating temp on choke should be fouling your plugs so bad that any other normal tuning won’t work because the plugs are toast.
You need to verify fuel solenoid click with the key. Click with key turned to run every time (not starting, just turn key to run).
Next, change the plugs to new.
If you don’t do both of those, I wish you the best.
So after you do both of those, solenoid is verified to click with key, cold engine, give 1 fast, full pump of gas pedal (then take your foot away from the gas pedal), choke all the way out and turn the key to start.
Once it starts, push choke in as far as needed to maintain 1500 ish rpm. By about a minute to 90 seconds, choke should be all the way in and idle.
If it didn’t start, do what’s necessary to get it to start. Then check timing with vacuum advance unplugged and the vacuum source plugged. Then go through setting idle speed and lean drop, etc.
How old is the gas? I’m just throwing some stuff out there at this point. Really need a baseline and methodical check of everything to properly diagnose.
Using a jumper to check the fuel cut solenoid ensures it works, but you need to verify it’s working with the key switch. If there’s a bad wire or something, you’re removing it by jumping so not a like for like test.
You probably have a vacuum leak, but if you’re running and driving with the choke on, there’s no point in diagnosing from here. Running to operating temp on choke should be fouling your plugs so bad that any other normal tuning won’t work because the plugs are toast.
You need to verify fuel solenoid click with the key. Click with key turned to run every time (not starting, just turn key to run).
Next, change the plugs to new.
If you don’t do both of those, I wish you the best.
So after you do both of those, solenoid is verified to click with key, cold engine, give 1 fast, full pump of gas pedal (then take your foot away from the gas pedal), choke all the way out and turn the key to start.
Once it starts, push choke in as far as needed to maintain 1500 ish rpm. By about a minute to 90 seconds, choke should be all the way in and idle.
If it didn’t start, do what’s necessary to get it to start. Then check timing with vacuum advance unplugged and the vacuum source plugged. Then go through setting idle speed and lean drop, etc.
How old is the gas? I’m just throwing some stuff out there at this point. Really need a baseline and methodical check of everything to properly diagnose.
- Thread starter
- #17
Yes it runs/drives fine with the choke out (engaged) and accelerates fine as well. I will check the solenoid with the key switch as you describe. Engine does start quickly after 1-2 pumps of peddle and choke out. But no way will it idle after 90 seconds without the choke engaged about 3/4. Gas is fairly new non-ethanol.
- Thread starter
- #18
Truck runs fine with the choke out….does not back fire and accelerates strong. Again this “gremlin” is once the truck is driven for about 15-30 minutes and gets warm/hot and I come to a full stop and it idles with the choke out…..the sudden high rev of the engine kicks in and I must push the choke in (disengage) or the engine will stall. If i do disengage the choke it idles beautifully. Makes me think it’s something with the emission system that causes a ‘vacuum leak’ where the choke is compensating for the extra air (leak) in the system but once it gets hot it (computer, vsv, ?) shuts off the leak and the extra fuel from the choke is then causing the racing engine/high rev condition that is immediately alleviated by disengaging the choke. I mean this is nearly 45 year old emission ‘gear’ so not surprised something in all that spaghetti isn’t working correctly. Once the weather improves I’ll get the truck back out and run it thru the paces and document the symptoms…..checking the fuel solenoid, vacuum leaks at carb/manifolds,(doubt that’s the issue) and anything else that’s recommended. I have a spare ‘computer’ so I’ll even try swapping it out as well. If no solution is found…..I maybe back on the board looking for help/reading about desmog and Sniper install. Thanks again for all the input. Really appreciate the help.
The choke is dumping extra fuel into the engine to assist with cold starts. The stock carburetor also has an idle up feature that is adjustable (see FSM) which increases idle while the choke is engaged (on). As suggested by @Skreddy above, the choke should be off as soon as the engine warms, the fast idle with the choke engaged should be a non-issue, as it should race with the choke on.
When I need to choke my motor at startup, which is only when its cold outside or the truck as sat for an extended period of time, I choke it to start it and have it disengaged by the time I pull away. If its below freezing, I find I may need to have the choke feathered open to assist in pulling away from stops until the needle on my temp gauge has started to move off of C
When I need to choke my motor at startup, which is only when its cold outside or the truck as sat for an extended period of time, I choke it to start it and have it disengaged by the time I pull away. If its below freezing, I find I may need to have the choke feathered open to assist in pulling away from stops until the needle on my temp gauge has started to move off of C
- Thread starter
- #20
Btw….i’ve read on other boards that a possible culprit of idle problems as I’ve described is the hot idle compensator…..from what I’ve read it apparently has a bi-metal ‘valve’ that opens and closes (artificially closing and opening a ‘vacuum leak’) depending on the engine bay temperature. In an earlier post on this thread it is the ‘gold’ oblong thingamajig that is on the side of the carburetor. Apparently other auto manufacturers put these things on carbs of cars in the 1970s vintage. Anyone had experience with this item?