Little Trucks, Big World

throttle bogs down and fuel sending unit....help!

I have a Weber 32/36 and after over a year of being off the truck for a full restoration job, I have a hesitation in throttle response upon first application of fuel.     The engine will literally "bog" down, but not stall, and then jump to life with a nice full rev of the engine.     It does not miss or anything like that, this is a simple falling off and then an immediate pick-up of engine rpm's.

The main problem is drivability of course since every time you want to step on the gas it flop sweats. If you place a heavy enough throttle application down sometimes you can push past it with only a small drop before taking off but then at times it will just fall flat and snap to life with a jerk of your head and a buck of the truck in response...not smooth at all for road use.

I was not sure if the Weber was getting the proper amount of fuel since my regulator was set for my old fuel pump that frankly..stunk.   I purchased a new OEM one for my rebuild (and a new fuel tank, lines, filters, etc.) and it still hesitated so I ran the fuel line straight from the fuel pump right to the carb (with the potential for too high of a fuel load) but it still hesitated just the same.

Is it possible that the other parts of the carb need to be taken apart and cleaned after being "down" for so long (i.e. needle valves, jets, etc.), would they possibly cause the issue?

Part 2:

The previously mentioned new fuel tank was installed and I used the original fuel sending unit because it worked fine previously, sadly now that i have it all installed and fuel in the tank the gauge is not working.

I checked the wires and cleaned the harness contact points but still nothing.   I used the ohm meter and checked the switch and it showed 93 ohms which would be "empty" on the gauge, which is exactly what the gauge is showing, problem is...it has about a half tank or so of fuel right now so it should register much lower at about maybe 35-38ish.

Upon testing the main wiring coming back to the switch the voltage was all over the place reading 2 volts one second and 11.59 the next, I couldn't make much of that really.

I am REALLY not looking forward to taking this tank back out and removing the sending unit now that it has a bunch of fuel in it to replace the sending unit.

If you have any ideas or better yet "experience" with these two items I would love to hear them.

Thanks guys!

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Engine off, look down the carb and work the throttle. You should see a strong squirt of fuel. This is the accelerator pump. If not working or weak it needs fixing.

Ground the Yellow/Whiter wire with the key on... you should get a full tank reading. No reading would indicate a faulty gauge or wiring between it and tank.

Ground the Black wire. If this gets any reading, the ground wire is at fault

As it reads 93 ohm, this would indicate the float is stuck in the down or empty position.  Drive it with sudden stopping to slosh the gas around. This may dislodge the float. Otherwise you will have to remove it..... again.

Thanks for the great tips!

So, I tried running a new ground to the black wire with no result, but i did get a full tank reading when I grounded the yellow.

Tried jumping on the bumper a bunch but that didn't do it, might take a more aggressive manuever to dislodge it if it is indeed just stuck.

I am getting a good stream of fuel when i tested the throttle with the engine off, but while running and looking down the throat i can see it stutter while activating the throttle.

First i get a little fuel and then it seems to spray irradically for a split second, then pick up again and rev freely, however I never see the left chamber spray or the throttle plate move at all.

The 32/36 is a progressive carb. This means that no matter what, when the primary is 1/2 or 3/4s open (or whatever it is) the secondary is forced to open also. Try opening the primary with the engine off. Make sure the primary opens fully and the secondary should begin opening at 60% or so. I don't believe the secondary does spray as the engine will be well revved up by the time it begins to open.

The accelerator pump diaphragm is on the outside of the 32/36 and can easily be removed and/or replaced if the pump output is low or erratic. Having said that, there is more to just off idle acceleration than the accelerator pump. It can be a lot of things including timing and ignition and wrong jet to clogged jet. Here's a couple of links to trouble shooting a 32/36 and setting the idle properly.



Finally got a moment where i could remove the carburetor and take it apart.

Upon opening i noticed that their were pieces of metal shrapnel in the fuel filter inspection port that looked like it was left over from fabrication and got stuck in their.

The jets look clean and all other parts also were in good shape.

I did notice that the small fuel filter that is inside had a 1/4" to 3/8" hole and the sides were sucked in like they were collapsing.

I ordered a rebuild kit and a new filter and we will see what that does for it.

Check out the slow speed circuit. On the inside of the carb base just above the the idle mixture screw is a slit. It's above the throttle plate so not used during idle. But as the throttle is opened intake vacuum is applied to the bottom of this vertical slot and sucks fuel out. Any blockage here will result in poor low speed throttle response. Farther above this is an air bleed that again is easily blocked. in fact the idle cut solenoid is just below this for shutting off idle fuel. There is also another (much larger) air bleed for the primary venturi that must be clear and the emulsion tube below it. 

Use a can of carb cleaner that comes with a straw so you can force cleaner through these small holes.

I know the 32/36 weber very well. From what I read about your issue I would first check to make sure the accelerator pump is functioning properly. The ports to the pump are extremely small and do plug up especially after sitting. The 32/36 is very dependent on the pump during off idle acceleration and low rpm throttle response . Look down the carb and hit the throttle, if you don't see a strong squirt of fuel then you found at least one issue. The 32/36 accelerator pump is not dependent on fuel pump pressure. It has it's own reserve it stores fuel from
Thank you both very much, those ideas will give me something more to look at and hopefully fix this problem

I have a short video of what it is doing, i hope it is able to be viewed.

Thanks again!
Well, maybe not, site won't load it.

If you PM me your email addy i'll send it to you.

Thanks again.

How much PSI are you getting from your fuel pump,should be no more than 3 PSI,I just installed a new Redline,32/36,and I installed a fuel gauge and it is reading 3 PSI.Maybe your fast idle screw needs adjusted up,Remove your air filter,turn throttle all the way by hand and hold then turn your buterfly,then go start,don't touch the gas pedal,after it starts,it should go to 2000-2500 rpm's,if too low,turn off and get flat head screw driver and turn fast idle screw in some,then go start and see where it goes to,adjust till it's in the 2000-2500 rpm range.I am using a oem fuel pump,BECK Arnley,it says it's not good to use a fuel pressure regulator to decrease the fuel pressure,will cause fuel to back up to the fuel pump causing it to strain and make noise,if it's higher than than 35 PSI,Then get another fuel pump.Also check the  2 fuel lines by the passenger side by the oil filter for leakage,mine leaked their.Also,go to Autozone and have your battery and alternator out,when I put Weber on,Alternator was bad,when I started it,it would die,went and had both checked out at Autozone and Alternator was bad,installed,started up,then idled fine.

I reset all my settings on the carb. and set them up for the new OEM fuel pump.

The new pump is pushing 3 gpm, no regulator, which is within spec.

Battery is new and alternator is charging properly.

Did you spray the base with brake cleaner while its running to check for leaks,or you can get a rebuild kit,or I would get 298.00 and get a new one.

Nah, didn't check vacuum yet, but it's out of the truck now and a rebuild kit will be here tomorrow, that is only $28 with the fuel filter.

If I'm dropping $300 i'll go a bit more and just install a higher output engine and stronger transmission.

Although that is easier said than done, but let's not get into that right now.


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