Weber carb issues, climbing steep angles

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.


Nov 29, 2003
I have a FJ40/2Fmotor, smog removed, all extra vacum ports plugged. I installed a weber 38mm carb The first week it was great. I then had to lean out the carb. This worked great for a bit. At this point I am still running slightly rich and the carb will not lean out any more.
The second issue is when I climb very steep inclines, or over high angled rocks I appears to flood out ( when trying to restart I get black smoke out of the exhaust)

Now I realize there are many variables to a motor properly being set up. Here are a few of the tweeks I have done before the carb was installed, adjusted the valves per spec, new plugs, new rotor and cap ( no points), new fuel pump, new fuel filter, gas tank removed and checked for dirt ( none found). I have re-check after 8 weeks of the carb installed, valve clearance, new plugs ( old ones fouled a bit) tried to lean carb ( no avail)

Once the engine is warmed up it "seems" to run very well accept for the two issues above. Meaning when the engine is hot it burns the gas better...

Can you point me in the right direction Why can I not lean out the mixture anymore? Why would the carb flood going up very steep inclines? ( if in fact it is flooding) or do I need lower gearing?

I live at 4500 ft - Thanks for any info!
I have the same set-up, with the same problems. The problem with flooding, although I'm not sure is a weber even has one, is the float bowl. When you bounce heavily, or attack intense inclines, the fuel spills over the float bowl, straight down into the intake. This enriches the mixture to the point that it won't even burn. Starts up fine, but belches out the black smoke you describe. And about leaning out the carb, you can only lean so much with your idle adjust screw. That screw is only to set the idle mixture. When the engine is reved, the idle screw is useless. You will have to change out your jets to a different size. I can't give you a recomendation because I have no clue what size belongs in my carb, let alone someone elses.
I have the same problem.

1. I rejetted, but your vehicle will be different. It was no help on inclines.

2. I lowered the float bowl, it didn't help either.

3. I installed an electric fuel pump and a regulator, as expected, no help.

4. I have had enough, it will have to do until I swap a 350 in.

5. Deal with it or go back to stock or go for propane or fuel injection or swap motors.

I have heard of flipping the Weber around so the float is behind the carb but I have not wanted to mess with it that much yet.
Bummer...I thought these issues were only with the Holley. My Bro has a holley on his with the same probs. I might try the turn around carb idea. Or somehow figure how to keep the gas from sloshing.

Are all the serious 2F users running stock carbs?

I will eventually move up to a vortec V8, just want to have some fun for the next 2 years with the 2F

Thanks for the replies
i searhed this topic and spent the better past of 4 hours reading all about it. Least I am not alone.... :'(
One thing I did find so far. My auto choke had only 8.5 volts going to it ( i used a line from my old carb) I hooked up a keyed 12v line to it. Now my choke is fully open when going down the road and idling. Now I need to test this on the trail...
whatever you do dont add a hi pressure pump. The guy who owned the '71 before me put one on, fuel made it into the oil and caused some seized bearings.... getting ready to rebuild her now.
I replace the old leaky fuel pump with the same OEM pump. I have not checked the pressure. The cruiser works really well I can get down the freeway at 70 MPH with pedal left, I can climb steep freeway grades with ease. I need to find a way to rock hop with out the stalling. If I cannnot get this weber to work I will go Aisan as suggested. There must be someone who knows the secret :'(

my engine is pretty much stock and i have the same problem. its bogs dowm going up steep hills and stalls when wheeling. iv rebuilt the carb, adjusted the float replaced the fuel pump and filter, and nothing helps.
I was advised to check the float level. Can anyone discribe how to do this?

The stock OEM fuel pump, how much pressure does it put out?
im just trying to bring back this topic to see if there are any fresh ides out there or if anybody has fixed this problem. if so, i dont check the internet to offen so if you know the solution to this please e-mail it to me
I run a different model weber (32 DIR) on my F engined truck and also have had similar issues with it.
First off I run the stock fuel pump with no extra pressure regulator. This has not been a problem on my setup as some others have had. It sounds like it isn't a problem on yours either from what you've described.
I lowered the float level on my carb to decrease the overrich effect on steep climbs. I don't remember the factory recommendation for float level on the 38, its much different than the 7mm in mine though (MUCH lower IIRC). Lowering the float level will also slightly lean out the overall mixture during normal running.
Depending on the linkage you have turning the carb around might work well. On steep descents you will get the same problem, but at least gravity is on your side. It might give you the opposite problem of fuel starvation on hills if the fuel level in the emulsion tubes drops too low though, thats something you'll need to test.
The electric choke not fully opening is definately a problem. But as mentioned, if its still too rich you will need to rejet both barrels.
As a side note I also run a 28/36DCDR weber (same series as the 38 except progressive oppening) on my Renault. On very hard cornering it also stumbles from feul slosh in the float boal. Very annoying .
Despite some problems I still like Webers. Very simple to set up in non-stock applications.
Good luck.
I must be the only fj owner on the planet happier with my weber than my old-POS aisen. I got the weber kit from man-a-fre that allowed me to keep the stock air-cleaner and linkages.

Another important point that is mentioned in the weber faq is that the weber carb only requires 3.5 lbs of pressure. Also the choke needs to be connected to a 12v ignition switch.

As for me you'll have a hard time convincing me to go back to the aisen :)
It starts better, runs better, and passes emissions.
You are not the only one...

I have had mine since '94, and love it.

Mine has been working great once I got my 12v to the choke ( old wire was only 8V) and did some fine point adjustments. I think I need to get lower gearing ( Orion) so I can crawl up the steep angles instead of bouncing up. At that point i will fine tune the float...

(BTW the stock fuel pump seems fine to me.)

This is a repy from TPI where I bought my carb:

1. Consider an electric fuel pump at 2-3lbs. Part # 28100-E & 28100-EP
2. Your coil may be weak. Consider #19500ADV
3. Trash in fuel line from old tank, consider JGT-12.
4. Choke out of adjustment.
5. Slow speed idle adjusted incorrectly.
6. Set float bowl at 3:30 (call tech)

here is a weber link for tune up procedures:
i have a 74 with 32/36 weber carb on it I know its different but i placed a T betweeen the pump and the carb with a line returning to the fuel return on the tank and all the excess fuel goes back to the tank and seems to work great. i was busting my head at first with a pressure regulator and elect pump but went back to the stock pump a used the T should workfor your's as well :cheers:
i have a 74 with 32/36 weber carb on it I know its different but i placed a T betweeen the pump and the carb with a line returning to the fuel return on the tank and all the excess fuel goes back to the tank and seems to work great. i was busting my head at first with a pressure regulator and elect pump but went back to the stock pump a used the T should workfor your's as well :cheers:

Cruiserfish, My 72 does not have a return to the tank and I seem to have excess fuel sitting in the manifold (I took the 32/36 off and it was puddled there). Any suggestions?
Keep the stock mechanical pump - add a good regulator if you can find one . Avoid that crappy chrome-dial Purlator/Holley/whatever brand , they are junk . Make sure you have a good heat insulator under that carb , later model Cruisers it's nice if you can get a carb cooler fan and make it work - it helps . Best insulators were the later model ones with the sheet metal heat deflector built into it .

Users who are viewing this thread

Top Bottom