need help adjusting carb (1 Viewer)

[liko]

I have a March 1970 FJ40 with the original F engine. Cruiser was not running well at all, hard a hard time idling without the choke at least half to three quarter. Thought it was dirty fuel (I hate ethanol) and/ or carb issues so I removed and cleaned the tank. Put a new fuel line in. A small micron fuel filter (like a fuel injected vehicle today might have). Cleaned and overhauled the carb. Disconnected the vacuum line to the distributor and plugged that. Eliminated the VSV and ran one vacuum line from base of carb to choke breaker. Found an intake manifold leak, so I replaced that with a used good condition manifold. New manifold gasket from SOR. Cruiser runs much better now, but still won't idle like I know it should.

Cold start- pull choke knob all the way, turn key, fires up and idles smoothly at 1100 pulling constant 20 inches of vacuum. (About 100 feet above sea level)

Warm up for a couple minutes (I am in hawaii its like 87 degrees)

Push in choke half way, idling at 700 a little rough, vacuum varies between 15 and 16 inches.

Push choke all the way in, engine dies.

Try to start........no dice.

Pull choke all the way out and start.....fires up, idling at 1100 again.

Driving me crazy! I am confused about which screw to use to adjust, also what is the choke breaker for? Seems to run better without the choke breaker vacuum connected, but seems important. A little guidance will go a long way, thanks in advance.

 

[Pin_Head]

The idle fuel mixture screw is brass and faces the valve cover. It is in the cast iron base. The idle speed screw is typically in the cast iron base facing the firewall. I don't see it in the pictures you posted. The ones I can see don't look like the idle speed screw.

Open the idle mixture screw 5 complete turns. If it won't run below 650 RPM using the idle speed screw, then you may not be getting idle fuel or there still is a vacuum leak. Check the operation of the idle fuel cut off solenoid and check for leaks again. If no leaks, then most likely a bad solenoid or the idle fuel port is plugged, you can try removing the solenoid and mixture screw and blow the passages out with carb spray and compressed air.

 

[65swb45]

Yup, sounds like a classic idle circuit/solenoid issue.

 

[liko]

thanks, trying that now. looking for that idle speed screw though.......carb is from a 71 that also donated the intake manifold, does that change the location of the idle screw?

 

[liko]

view from driver side inner fender well....

 

[65swb45]

Keep looking. Your red line points to the throttle positioned, and the orange to the choke.

 

[liko]

gotcha!!!

found the idle speed screw, thank you.

Tightened all the way in, then 1.5 times out.

Pulled choke out all the way.

Started right up.

Idling high....above 1200

Adjusted with my newfound idle speed screw down to 1100 rpm

Let engine run for a couple minutes.

Noticed vacuum down to 18-19 inches

Pushed choke in to 3/4 closed.

Idling rough at 800

Vacuum down to 15 inches and bouncing.

Pushed choke knob all the way in.

Adjusted with idle speed screw down to 700 rpm.

Idling rough......died out at 650 rpm.

Won't start.

Pull choke all the way out.

Fires right up. Why is that?

 

[edwjmcgrath]

Edit. If it will idle at 700, it's likely not the solenoid.
Try adjusting the idle mixture.
Finally, are you sure you still don't have a vacuum leak somewhere? Hose disconnected?

 

[Pin_Head]

I still think it is a lack of idle fuel. At 15 inches of manifold vacuum, you are just pulling fuel out of the main nozzles because the throttle is open too wide to idle. Take a peek inside to verify that it is running off the main nozzles at 700 RPM and if it is, fix the idle fuel solenoid or clean out the idle fuel passages or both.

 

[landcrusher909]

The idle fuel solenoid might be gummed up, pull the possitive cable of the battery, turn the key on now stand over where you can re connect the possitive battery cable listen for the idle fuel solenoid to click if you dont hear anything it could be bad or stuck. If it turns out to be bad shoot me a PM and I can get one mailed off to you.

 

[Fast Eddy]

Can the solenoid click and still be bad? Any way to test it?

 

[edwjmcgrath]

Yes. If it's working, you can blow into the end and air will come out.
If you've got a single wire solenoid and it has been removed from the carb, you'll have to clip a ground wire to the body of the solenoid to get it to work.

 

[liko]

I have been actively searching for another vacuum leak using the brakleen method, sprayed all over the manifold and the gasket, harder to get underneath. Currently using the brake booster vacuum line for my vacuum gauge, I will continue to look though. About to go check the operation of the solenoid right now, thanks.

btw- heres a pic of vacuum deletion/ re-route

 

[liko]

using positive battery cable/ key method.....no click, bummer. Removal in progress.

 

[liko]

So I removed the choke cable then the solenoid, hooked up some jumpers to the battery and it moves in and out.

Sprayed some carb cleaner in the solenoid opening and then blew air in which went through to the barrel of the carb.

I cleaned the contact areas for the ground wire and where the solenoid contacts the carb.

Forgot to hook up the choke cable.

Turned the key and it fired up instantly! No choke required. Adjusted idle to 700, vacuum steady at 20 inches. Connected the choke cable and time for a beer, only 1030 am.....who cares. You guys are fricken heroes. This was driving me nuts. Still a long way to go, but thanks again.

some more pics

 

[Pin_Head]

You are getting closer, but you don't want to see fuel coming out of the main nozzle at idle. Adjust your idle mixture and speed now. Set the idle speed to 650, then open the mix screw just until the idle speed won't increase any more and turn the mix back in until the speed drops by 50 RPM.

 

[liko]

i thought i was done.....thanks for the tip. I took her out for a drive around the hood yesterday and there is some hesitation/ sputtering?

 

[Pin_Head]

hesitation and sputtering off idle is a classic sign of lack of idle fuel as it failure to idle below 650 without pulling fuel out of the main nozzle.

 

[liko]

Let me start by saying thanks for your help pinhead, mark, crusher, ed and anyone else

Set the idle at 650

Adjusted the mixture screw (facing valve cover) until idle topped out at 750 RPM

Backed down the mixture screw to 700 RPM

Vacuum is down to 19 inches, should I be concerned?

Took a peek inside carb, no more fuel from main (jet?) at idle speed

Gave the gas a little nudge and sputtered and nearly died, if I don't let off the acclelerator it will die. When I gas it and it hesitates/ sputters, I let off the gas and it idles just fine.

The mechanic at work said it could be points/ coil related........not tryin to open that can of worms just yet

note to self, don't be lookin inside barrel of carb when you gas it........lost some eyelashes on a mini backfire

 

[Pin_Head]

It still sounds like there isn't enough idle fuel to feed the transition slot so that it runs smoothly between idle and higher RPMs.

It is probably not ignition related.