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well my weber is on and it is great except it hesitates when you punch the gas. the timing is right and the vacuum advance is working. it didn't do this with the hitachi. so it has to be something with the carb. it acts like the accelerator pump is not putting out enough gas. anyone ever had a problem with this. i've tried adjusting the idle mixture screw and have it set right, but it still does it.

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1980 chevy luv 4x4 1.8 liter
1979 luv long bed parts truck
1984 2wd isuzu pup parts truck

"A man who says it can't be done shouldn't interrupt a man doing it."

I don't really know anything about webers, but maybe its jetted to rich for the 1.8L??

Did you pull the breather and look down the throat to see if the accelerator shoots a stream of gas? Is the progressive linkage opening the second barrel? Does it run good at high speed?

yea i looked and it shoots a good steady stream of gas when u push the accelerator. when u push the throttle fast you can see it shoot gas, then when u get it pegged out you hear a little air mixed in with the gas that the accelerator pump is shooting out. (all this being done with the engine off) it makes me wonder if the accelerator pump is running out of gas. i bought this weber as a kit for the luv so it should have the right jets. it runs great at high sppeeds, only messes up when you punch it.

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1980 chevy luv 4x4 1.8 liter
1979 luv long bed parts truck
1984 2wd isuzu pup parts truck

"A man who says it can't be done shouldn't interrupt a man doing it."

if its not fully warmed up then it will hesitate. My luv will down right take a nose dive if its not warmed up becouse i try to take it on the highway. Maybe this is your problem, it just seems to be the nature of bigger carbs. Try running it around conservitavely untill its warmed up then see if it still stumbles.

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1980 LUV 4x4, going under re-construction...

MEPR is right. My Weber stumbles before it's warmed up. After that, it'll chirp the tires. Something the old Hitachi couldn't cause even on a hot July or August afternoon and blacktop. Sorry, I thought it was installed in your truck.

the weber is on my truck and it still hesitates after driving it 30 min. on the freeway. i guess i need to call weber i think there is something wrong with the accelerator pump.

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1980 chevy luv 4x4 1.8 liter
1979 luv long bed parts truck
1984 2wd isuzu pup parts truck

"A man who says it can't be done shouldn't interrupt a man doing it."

Iv set up webers for my frinds race car .
iv got one that was going to be on he car but he can run a holly4412.

so its on my luv . it can give it two much fill if you hit the gas to fast.
its got a holly 30cc accelerator pump. custom made secondary cam.

might have to jet that sucker down...

its like its not getting enough fuel, not too much. its only when i punch the gas, runs great otherwise. this carb should be jetted for my luv, it cost me $300 from weber. it seems to me like the accelerator pump is just not putting out enough gas.

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1980 chevy luv 4x4 1.8 liter
1979 luv long bed parts truck
1984 2wd isuzu pup parts truck

"A man who says it can't be done shouldn't interrupt a man doing it."

Where is the accelerator pump located?? Pull the fuel line off the carb and whirl it over, check to make sure a NICE STEADY STREAM of fuel comes out. It should not need jetting if it was jetted for the 1.8L. It does have the symptoms of a richly set carb. though. Right now my SBC in my LUV is running rich, runs great too, except when you punch it, it stutters. Same thing thats happening to you. But if you say the carb was jetted correctly for the engine then I guess its not that. Like I stated before I don't know much about webers but im just throwing my two cents in I have gathered from other engine experiences ...

well is you air cleaner new? On my ford if my air cleaner is vary dirty it has no power becouse it just starts loading up. For the longest time i thought it was running lean, but it was running rich...

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1980 LUV 4x4, going under re-construction...

Mine does the same thing. I have just learned to live with it. I have tried everything I know about it, and the dead spot is still there.

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Hammer to fit, paint to match.
If it aint broke, don't fix it.
There's always room for duct tape and bailing wire.

WATCH YOUR PIEHOLE!!!!!!

ive been told that getting the flywheel lightened improves response time heeps, dont quote me on this but its worth looking into

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I said no to drugs....But they just wouldn't listen!

No matter how good she looks, some other guy is sick and tired of putting up with her crap!

If you ask weber I bet they'll try to sell you on a new fuel pump. That may or may not be the problem, but you can test the pump fairly easy for volume. If you have a gauge you could also test the pressure output. Knowing both would at least give you some ammo to get the right answer from weber.

You could have a vac leak somewhere, check that with some carb cleaner. Spray around the base of the carb and adapter, on each intake runner right at the head, and around the major vac connections like the brake booster. There also could be some junk stuck somewhere in the carb. The accel pump is easy to remove and check. I think I'd pull it and look for faults or crud stuck in there somewhere. A crack or hole in the pump diaphram might be sucking air and not giving it a full charge of fuel.

Oh yeah, if you haven't yet, change out the fuel filter. From my experience plugged filter/low fuel flow causes a high RPM stall though, not a stumble off idle or low RPM.

Just to add my 2 cents, my 77 stumbles when first started but does not after just a minute or two or warm up, and my 79 runs rough cold but takes right off when you stand on the gas. I had a weber on the 79 for a while and it didn't change that behavior in the least.

Just out of curiosity what was the idle mixture adjustment? (how many turns of the screw out from seated) It should be around 3 turns out or so, depending on the motor and the jetting in the carb. If you've got doubts on your adjustment, you could lean it out a bit and see what effect it has. Try a half turn lean then back again and see what kind of difference you notice.