1966 FJ40 with big window 1bbl: Engine dies when you push in the choke (1 Viewer)

[joestewart]

Looking for ideas here. This is my buddies 1966 FJ40. Someone had installed an engine from a later model Land Cruiser (possibly a '68 or '69), so it has the later model manifolds (see photo). The current owner adapted a big window 1bbl carburetor to the intake manifold. Starts up and idle fine (perhaps a bit rough though), but as soon as you push the choke in, the motor dies. This happens even after the engine has warmed up.

Today we disassembled the carburetor and blew out all the passages. Nothing seemed to be amiss. We have compression checked this motor and we get 150psi in all cylinders except for #4 in which we got 140psi. There appears to be plenty of vacuum (although honestly I have not actually measured the vacuum - there is just plenty of suction when you cup your hands over the intake).

He is running an aftermarket distributor. I don't know the brand or model of the distributor, but I do know that it has no changeable points in it and that there are no vacuum ports on it.

I am uncertain as to whether or not he has actually checked engine timing with a timing light. Next time we work on it I will hopefully do this.

Looking for ideas on how to approach this problem. I looked at old posts, and some suggested checking the fuel shut off solenoid, but this particular carburetor does not have one.

Can anyone point me in the right direction? Thanks

 

[crawsfire]

Sounds like a vacuum leak. Have you sprayed carb cleaner around the base of the carb and your tc shifter hose to see if the rpm increases? Those adapters are notorious for leaking. Where does the black rubber hose from the adapter go.?

 

[joestewart]

Thanks. I have not tested for vacuum leaks yet, but will do so in short order (it may take me a few days though). That black hose goes to the PCV valve.

 

[joestewart]

Additional photo

 

[peesalot]

Carb idle circuits are plugged, bad gas in fuel bowl, water in fuel, if it runs choked then it's probably a little carb cleaning needed.

 

[ClemsonCruiser]

As Crawsfire mentioned it certainly sounds like a vacuum leak. Along with spraying carb cleaner around you can pull the vacuum line going to the 4wd vacuum valve and the one going to PCV. Block those off at the carb base and intake manifold respectively. If it runs better with those blocked off you’ll know the problem is in one of those assemblies. If it still runs bad then it’s likely a leak between the carb base, adapter, and manifold.

 

[65swb45]

Pulling the choke is either creating additional vacuum where there is insufficient vacuum otherwise, or bumping the throttle opening (a ‘68D40 carb has a link that connects them) so that it is running on the primary, when it can’t on the idle circuit.

Get a vacuum gauge.

 

[middlecalf]

And make sure your PCV valve is closing (rattles).

 

[joestewart]

Got my work cut out for me! Might be able to accomplish some of these investigative approaches as early as tomorrow; if not this weekend. Forever indebted to this forum.

 

[ryanwk628]

Mine was doing this when the fuel pump was going. I kept assuming it was in the carb but it kept getting worse. I think the extra vacuum of having the choke on was helping it, but the pump was not enough on its own. A new one from city racer sorted that issue right out