Rebuilt carb won't run without choke

[2 E L O]

Tried searching but couldn't find anything with this unique scenario...

'84 FJ60, 2F, 286k miles. Just bought the 60 a couple weeks ago.

Before carb rebuild it would run perfectly fine at times, then all of a sudden it would stall. Start right back up, run for 1-2 seconds, then stall. Start right up, then stall. Rinse and repeat. Throttle input or choke did not matter. New fuel pump, fuel filter, air filter, and spark plugs (appear to be OEM parts installed by PO's mechanic). It would do this when engine was at temp or cold.

Rebuilt carb (by me) with kit from Cruiser Outfitters. I feel pretty good about everything going back together well. I used Pinhead's videos and the FSM. I also replaced all the vac hoses on the driver's side of the engine with the 3mm and 5mm silicone hoses while the carb was out. Still need to do passenger side hoses...

Starts up and runs great with choke (around 2k RPM), will stay running great at lower engine speeds 700-800 RPM) all the way to last click of the choke, but without choke it stalls. I can keep it running with throttle input (without choke) down to about 700ish RPM.

Fuel bowl level looks good through sight glass--I adjusted float per FSM.

Idle mixture screw turned all the way in, then backed out 1.75 turns.

Tried to find any vac leaks using carb/brake cleaner. Only place I got any increase in RPM was around the primary throttle shaft on front side of carb. Is there any more scientific way to check for vac leaks with a vac gauge? I believe I may have a gauge...if not, I could buy one...

Sounds like it may have an exhaust manifold leak...getting the indicative little "tick tick tick"... Add it to the list of "to do's"...

Fuel cut solenoid didn't give me any problems before carb rebuild...could it be a freak coincidence that it failed at the same time as rebuild or could I have damaged it somehow?

Thanks in advance for any help!

Photo just for interest...

 

[Output Shaft]

Maybe some crud still blocking a slow jet at idle. When you give it throttle, the primary jet comes into play, providing fuel. Same as when you pull the choke on a warm engine. If you've still got the BVSVs hooked up correctly in the thermostat housing, the choke acts only as a throttle positioner when the engine is warm, not as a choke.

It's not an ignition issue, since the engine runs at higher rpm, and it's not a main jet issue for the same reason. It's a fuel supply issue at idle. That is governed by the slow jets.... and lack of vacuum leaks.

It's easy to inadvertently get crud into crevices when opening up the carb and fiddling with it.

 

[2 E L O]

Dang. I feel like I got everything very clean and used the carb dip...and then blew everything out with carb cleaner before putting it back together. So, vac leak or clogged slow jet would be primary cause(s) of this issue? I'd like to verify no vac leak before I tear it all apart again, but I'll do whatever necessary to get this thing running right...

EDIT: Just found my vac gauge.... Which hose is the best to test for vac levels at idle? What pressure range is normal?

Thanks!!

 

[Output Shaft]

Use the little vacuum hose pipe that juts out from the brake booster big vacuum hose. At sea level, vacuum should be near 20 inHg. Major vac leaks can be seen with a vac gauge. Small ones can't.

 

[g-man]

My guess is an internal vacuum leak caused by not putting something back ...like a big hole where there should be a slow jet or check ball, otherwise check your fuel cut solenoid make sure it's clicking with 12 volt jumper.

 

[2 E L O]

My guess is an internal vacuum leak caused by not putting something back ...like a big hole where there should be a slow jet or check ball, otherwise check your fuel cut solenoid make sure it's clicking with 12 volt jumper.

Ha! That would suck... I didn't have any left over parts--that was my first warm fuzzy as I buttoned everything up... I specifically checked and double checked to make sure both of the check balls were there. Small ball in the inlet--the one with the little PITA retainer, right? Big ball in the outlet--the one with the small metal plunger/piston. Also pretty sure I got all the slow/main jets in place. But...never say never, right!? I'll have to check the solenoid. I assume the technique can be found with the search function...

 

[gregnash]

Your fuel screw is turned in too far. Read some of the tuning posts from @FJ40Jim and you will see that the cruisers usually run well with 3-4 turns out. Doesn't look like you are desmogged but I would turn the fuel screw out more.

 

[2 E L O]

Your fuel screw is turned in too far. Read some of the tuning posts from @FJ40Jim and you will see that the cruisers usually run well with 3-4 turns out. Doesn't look like you are desmogged but I would turn the fuel screw out more.

Correct--all smog equipment still present, but I will give this a shot! I believe FSM said 2 turns out and Pinhead said 1.5--or vice versa--hence my reasoning for 1.75... But this is super easy to change so I'll give it a shot first! Thanks!

 

[g-man]

You can check your fuel cut off solenoid w/out removing it from the carb. I think if you just leave the key in the acc or on position and unplug and then reconnect the green wire connector at the solenoid it should "click" If it does not you should take a multi tester and check for current coming to the connector. May just be a corroded or loose connection at the green connector.

 

[gregnash]

You can check your fuel cut off solenoid w/out removing it from the carb. I think if you just leave the key in the acc or on position and unplug and then reconnect the green wire connector at the solenoid it should "click" If it does not you should take a multi tester and check for current coming to the connector. May just be a corroded or loose connection at the green connector.

This was the other thing that I was thinking but the thing that made me believe that it is NOT the fuel cut solenoid is the fact that he can get it to idle down to 700ish (with choke pulled out one click). For me when mine went out in January this year after rebuilding the carb and head it would either run or not, so if the choke was pulled out regardless of clicks it was running at 1500-2k rpm.

And with regards to the fuel screw turning out more.. basically from what I remember reading from Jim is that the FSM recommends the 2 turns out for a completely new engine where the carb has not been diddled with. For the truck to really run where it likes your starting point should be 2 turns out then keep going from there. I could be wrong but have a feeling that since Jim liked my post I was probably on the right track.

 

[2 E L O]

Major progress!!!

1.) Checked fuel cut solenoid. Ignition in 'on' position, disconnected/connected green connector and got audible clicks every time. FCS appears to be good.

2.). Hooked up vac gauge and was reading 14"wc. I'm at 4,100' elevation. Vac seemed low. Had some minor RPM and vac fluctuation. Idles with very slight choke or throttle input at 700rpm. Also, apparent exhaust leak quite audible. Video:

3.) Adjusted idle mixture screw from 1.75 turns out to 4 turns out. Started right up, turned off choke, stayed running at idle!!!!! Wooohooooooo!!! Vac improved to 17-18"wc. Thank you @gregnash!! Maybe I was just happy and distracted about it running on its own, but it didn't seem like the exhaust leak was as noticeable after this adjustment. But, I can't think of any logic behind that...probably my mind playing tricks on me.

So, it idles on its own very well but maybe a little low--around 500rpm on stock tach--not sure how accurate these are, and seems like it's rich based on exhaust smell and awful performance when messing with throttle when in neutral. Bogs really bad unless I apply the throttle pretty slowly... See video #2:

So, time for the lean drop tuning, and it's probably wise for cap/rotor/wires/plugs replacement. Any other suggestions? Probably a valve adjustment sooner rather than later... Something else I need to learn how to do!

Thank you all SO much for the help!!

 

[unklwedy]

One thot, Open choke and throttle plate and using flashlight examine the exhaust manifold surface just below carb for cracks.

 

[Output Shaft]

Checking valves is definitely next on the list. Tight valves can make for rough idle.

 

[gregnash]

Yup definitely time for the lean drop. If your fuel screw was exposed then that means it has been tweaked with in the past and the factory settings are gone. Now comes the fun part of playing with multiple variables.

First and foremost I would definitely do the valve lash and get those things within spec. From there do the lean drop method as you will at least know that you have proper valve lash. If things are still having issues then move on to doing timing and whatnot. For the time being you can definitely adjust the fuel screw in a bit while playing with the idle screw, maybe back off to 3 or 3 1/4 turns for the fuel screw and see how she smells and if she still bogs. Now it is all about fine tuning.

 

[2 E L O]

I'll check to see if I can see any manifold cracks through the carb... I guess I should have checked that while I had the carb out...

Valve adjustment moved up to next on the to-do list... I've never done it before, but it sounds like kind of a pain... I've read through some of the threads on it. My basic plan:

1.) Get engine up to temp
2.) Strip off the air cleaner and valve cover
3.) Find TDC
4.) Adjust valves
5.) Rotate engine 1 turn
6.) Adjust remaining valves

It sounds like a pain to try to somehow run the engine while having the air cleaner and vac hoses connected to check the existing valve lash--so I figured I'd skip that step and adjust all of them since it's probably not been done in a decade or better... Good plan? Terrible plan? Input is appreciated...

I'll plan to get a new valve cover gasket...anything else easy/cheap to replace while I'm in there? This thing appears to have oil leaks everywhere, but I haven't had a chance to degrease and identify actual sources. But, given the age and miles I'm happy to replace gaskets/o-rings proactively even if they're not currently having issues...

 

[gregnash]

Get the little grommets that hold the valve cover down on the valve cover bolts... Actually best way to do this is to get the engine up to actual temp which means getting it out and run it around town for a good 30 minutes to an hour.
While the engine is still running start pulling things off, you can get as far as the valve cover off before you need to shut things down. If you can get a buddy to help with getting the truck to TDC on #1 and then go through your adjustment cycle with one holding the feelers and one making the adjustment.
Then go to the second set and adjust those valves (setting them to TDC). Once that is done start the truck back up and run it for a bit to get it warmed back up. Shut her down, pull the plugs and adjust the second set again, this way you can ensure you are hitting them all while they are approximately same temp (front set vs. back set).

There are some guys out there that can adjust the valves while the truck is running and somewhat tune by ear and feeler but I am not that guy so the method above is how I do it. Actually once leg is better I plan on doing this for my truck as it is about time.

 

[Output Shaft]

After listening to the 2nd video with you tapping down on the accelerator and the engine sputtering before it starts to rev, that's sounds like classic accelerator pump malfunction.

I know you said you rebuild the carb, but what may be happening (I think) is when you're quickly pressing down on the throttle, the throttle plate is opening, but gas isn't getting squirted down into the manifold from the accel pump as it should. So the engine is starved of gas for a moment, leans out, and stumbles before the vacuum eventually pulls gas out through the primary jet.

If you can very slowly increase the throttle, bit by bit up to 2500 and it doesn't stumble, but if you stomp on it and it does..... The accelerator pump circuit is in the crosshairs.

 

[CuCruiser]

I will just chime in with a pep talk for you since I was in your shoes with my new-to-me '84 FJ60 this spring.

That fresh clean carb WILL run great when you get it tuned. I know it sounds like it's so far out of adjustment that it can't be made right but follow the lean drop method and it will purr and put such a smile on your face you'll feel like a rockstar. Then it's YOUR CRUISER! YOU MADE IT LIVE!
And that ticking very well could be valve noise and an adjustment might be all that's needed. Most likely if you've never done this kind of thing before you will do it several times before you're satisfied. I think I have adjusted the valves three times now in as many months as I've owned it, by as many different methods. Any way you do it, it is unspeakably fiddly but when that thing runs like a top it's worth it. NOW GET OUT THERE AND MAKE IT GO!

 

[2 E L O]

After listening to the 2nd video with you tapping down on the accelerator and the engine sputtering before it starts to rev, that's sounds like classic accelerator pump malfunction.

I know you said you rebuild the carb, but what may be happening (I think) is when you're quickly pressing down on the throttle, the throttle plate is opening, but gas isn't getting squirted down into the manifold from the accel pump as it should. So the engine is starved of gas for a moment, leans out, and stumbles before the vacuum eventually pulls gas out through the primary jet.

If you can very slowly increase the throttle, bit by bit up to 2500 and it doesn't stumble, but if you stomp on it and it does..... The accelerator pump circuit is in the crosshairs.

Accelerator pump was my first thought, too, as I had to deal with this on my old Mustang--but that was more of an accelerator pump sizing issue rather than it malfunctioning.

I'm not sure what to think...I went through the lean drop method tonight, but I'm a little baffled. It ran best when I backed the IMS wayyyy out. I didn't count how many turns, but I'm guessing 6-8ish. I was worried about backing it out so far that I would run out of threads! When I did this the stumble/bog when punching the throttle at idle got better, but it wasn't eliminated. But, after seeing it change some today I'm more confident accelerator pump is OK, but valve lash/ignition/timing could be contributing to the issue...

Also, why the F did Mr. T locate these idle mixture and speed screws in areas that are such a royal pain to adjust when the carb is on the truck? The IMS is impossible to get to while the air cleaner is on, unless there is some nifty trick I'm not aware of... Yet the FSM says the air cleaner/filter should be installed while doing the lean drop method... What gives?

I ordered valve cover gasket, dizzy cap/rotor, spark plugs, and plug wires today. Once that stuff comes in I'll get them installed and get the valves adjusted, set the timing, and do the lean drop method again.

I'm going to take it for a test drive tonight. Hopefully I won't have to call for a tow again!

 

[FJ40Jim]

The AP is weak.

Backing out the IMS excessively kinda hides the weak AP.