'75 FJ40 - Intermittent stalling at idle (1 Viewer)

[aging fleet]

For background, the Cruiser is a de-smogged CA '75 with less than 700 miles on the original Aisin carb that JimC rebuilt over the winter. It's driven almost daily as long as it isn't raining and tonight when it acted up, I had already driven it earlier in the day with no issue. I've done no recent mechanical work.

On to the problem, I went to grab a pizza for dinner, on the way home after a hot start, it was running rough and stalled after backing out of my parking spot. Any time I needed to stop, the idle would begin to drop and would eventually stall if I didn't give it some throttle or partial choke. I stopped in a parking lot on the way home and popped the hood to see if I had fuel at the carb. The fuel level was so high I couldn't read the level through the sight glass (confirmed it wasn't empty). When it stalled, I could get it to restart using the hot start procedure (gas pedal down about 50% while cranking).

I feel like the over-filled fuel bowl may be my issue (stuck float?), but I took a look at the following also...

1. Visually checked the vacuum lines, they're all new and nothing looked out of order. Given the desmog, there aren't a lot to check. Emissions computer is removed.
2. My brake booster probably needs to be replaced, just in case it was causing a vacuum leak, I blocked the vacuum supply to the booster and no change.
3. Checked for power at the fuel cutoff switch, it clicks when the ignition is turned on, but can't confirm it's actually working.
4. Pulled the plugs, it's definitely running rich, but the plugs weren't wet (just really sooty). I wire brushed them clean, reinstalled, and no change.

If my float is sticking, or there is an issue with the needle valve that causing too much fuel to reach the bowl, could that cause the stalling? Anything else I should think about?

Thanks for the help everyone.

 

[fjc-man]

You’ll need a carb kit or at least a top gasket so you can take the top off to access the float and needle/seat. Sounds like the float might have a leak, not stopping the float bowl from being over filled causing flooding.

 

[aging fleet]

You’ll need a carb kit or at least a top gasket so you can take the top off to access the the float and needle/seat. Sounds like the float might have a leak, not stopping the float bowl from being over filled causing flooding.

Thanks for the suggestion, thinking that may be my next course of action. Since Jim was in it recently, I may just swing by his shop to have him take a look.

 

[aging fleet]

Update for today.

Started it up thinking I would move it to the back of the garage so the 100 would be in the daily driver position. Checked the sight glass while running, again fuel level was above the glass, but it was running fine with the choke. Took it around the block (about 2 miles), about half way around I pulled out all the choke and it started stumbling again at a red light. Added about 20% choke and did a few full throttle pulls back to the house. Popped the hood once I was back in the driveway and the fuel level was right where it was supposed to be at the middle of the sight glass, pulled out all the choke and it idled fine.

Somehow flogging it temporarily fixes the issue.

 

[Paul_A]

A speck of something may have gotten past the fuel filter and into the carb, sticking in the needle & seat. A good carb cleaning, new fuel filter and maybe even a secondary cheapo clear in-line fuel filter just before the carb may prevent the reoccurrence, especially if you got spooge floating around in the tank. Sometimes a good rap on the side of the carb, like an old Dumont television, will set it straight.

 

[65swb45]

If you’re running the original fuel line from the pump to the carb, you may have shellac coming off the inside of the line. An upstream fuel filter will not fix that. Nor will cleaning out the carb.

Replacing the line will.

Anyone finding this information useful is welcome to hit the like button.

www.marksoffroad.net

 

[aging fleet]

Mark, Paul, appreciate the input fellas.

 

[45Dougal]

How is the weather during these problems, and how is your spark?
Ignition coils and ballasts which were fine when cold can complain when they're hot.

 

[aging fleet]

How is the weather during these problems, and how is your spark?
Ignition coils and ballasts which were fine when cold can complain when they're hot.

Hey @45Dougal, it's happened a few times in varying temperatures. It's been pretty hot recently and since the issue cleared up on Saturday it's been running fine. Once the weather turns for the worse, I'll replace my fuel lines and my fuel level sensor since it's been acting up. While in the tank, I'll see if there is any debris floating around.

 

[mattressking]

Pop the lid off the carb, inspect float needle for wear, set the float height and droop to factory to start or check against factory specs to start with gasket removed. High float level is very simple to sort, either a failed float, damaged/worn needle, poor height adjustment or debris in circuit between needle and housing is causing the overfill.

Vacuum measurement is not done visually, you need a gauge, anything else isn’t reliable - make sure you’re above 18inHg.

 

[brownbro]

same problem here...was working fine except for the first start up off the day i had to pump the pedal 5-6 times....wanted to fixed that ...the fuel level at the time was a little bit below the mid level in the glass...so i removed the top an adjusted the float....closed to the 7.5mm....but it back on.....won't stay running w/o the choke.....F%$# what was i thinking....i had done a new carb kit 2 yrs ago.....now the acc.pump rubber is damage and i need a new gasket for the top....if it ain't broke don't touch it.. waiting for a new carb kit....will be in touch later if cannot make it run properly. i had this fj for the last 23 yrs an i wouldn't have been able to keep it without all the knowledge on this web site. i will sure check all what was suggested above.

 

[aging fleet]

Pop the lid off the carb, inspect float needle for wear, set the float height and droop to factory to start or check against factory specs to start with gasket removed. High float level is very simple to sort, either a failed float, damaged/worn needle, poor height adjustment or debris in circuit between needle and housing is causing the overfill.

Vacuum measurement is not done visually, you need a gauge, anything else isn’t reliable - make sure you’re above 18inHg.

Hey, didn't see this until today. It hasn't acted up for about 4 weeks (driving it almost daily) and when it's running well the float height is right where it should be. I think you're all on to something regarding debris in the circuit so I'll be taking a closer look at my lines once the weather turns. I've never checked vacuum so I'll add that to the list too.

Thanks