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Weber Carb Adjustment


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I posted this  in the past but I couldn't find the responses so I'll ask again.

I have 3 Subaru 4wd wagons; one '86' and 2 '87's'. One '87' still has the Hitachi carb and starts and runs fine with no problems. I replaced the Hitachi carbs on the  other '87' and the '86' with used DGEV Weber's and they are both hard starting. Once they start they run fine but I have to pump like crazy and crank the started for about 6 to 8 seconds 3 times before they'll start, even in warm weather. I've also tried pumping a couple times and then just holding the gas peddle to the floor but still end up pumping the bejesus out of them to get them to start. Initially they idle at about 1200 to 1500 RPM but once they warm up and I kick them down from the fast idle they idle at 800 RPM and there's no hesitation on quick acceleration. They have electric chokes and the butterflies are closed when starting. Could I have them set too lean? I don't want to have to use starter fluid and I don't want to burn up my starters. The '87' does have a stumble at about 3500 RPM's but that goes away when it reaches operating temp. I drove to the Woodland Walmart ( about 5 mi. ) and was in the store for about 30 min. and had to crank it over several times before it would start. It was 70 degrees out. Frustrating!

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Ok so i just went out adjusted my carb and got car running again. I removed the filter from weber and push on the gas. The butterflies would fully open. I wnet and started messing with the electrick choke adjusted and was able to get the butterflies to a closing point. I did this while engine was stone cold. The car started right up. 

I then let the car run for about 10 minutes so it can warm up. When engine was warm and butterflies were fully ooen i shut off engine so i can then adjust the 1 air screw my weber has. I firt bottomed out the screw and came back 2 1/2 turns. Them i restarted engine. From there you back up screw and listen closely to the idle and turn screw until you get your maximum idle. When air screw was adjusted i the adjusted the idle control screw and brought my idle rpms down a bit. Now i will let the engine get stone cold again and see of my adjustment worked. I will bring an update soon. 

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Been working on the front brakes on my "86' Soob today and in between I did some carb adjusting. I think I'm doing pretty much the same as you're doing. at operating temp. I readjusted the choke so the butterflies were all the way open but loose enough so they could be wiggled and set the idle at 800 RPM's. I turn the air screw counter clockwise until the engine starts to stumble. Then I turn it clockwise until it starts to stumble, then center it between those two points. Just have to adjust the fast idle in the morning when it's cold. Hope all this makes a difference.Thanks for the response.

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  • 2 weeks later...

Did the same adjustment on the Weber on my '87' but still have problems with it. Seems to drive fine on flat or mild inclines but as the incline gets steeper, it starts to cut out, slow down and sometimes backfire through the carb. It's maybe a half mile out of town on an uphill grade to the freeway. I get about half way up it before it starts to cut out. It doesn't stall. When I push in the clutch and feather the gas peddle the engine smooths out. But I'm limping up the hill out of town at 35 mph in a 50 mph speed zone. I've checked the timing, vacuum advance, coil, and spark plug wires with a timing light ( steady blinking ). But then It runs fine when it's in the barn. There is a slight hesitation when I stomp on the accelerator.  It only gets squirly under a load.

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22 hours ago, 3crows said:

Did the same adjustment on the Weber on my '87' but still have problems with it. Seems to drive fine on flat or mild inclines but as the incline gets steeper, it starts to cut out, slow down and sometimes backfire through the carb. It's maybe a half mile out of town on an uphill grade to the freeway. I get about half way up it before it starts to cut out. It doesn't stall. When I push in the clutch and feather the gas peddle the engine smooths out. But I'm limping up the hill out of town at 35 mph in a 50 mph speed zone. I've checked the timing, vacuum advance, coil, and spark plug wires with a timing light ( steady blinking ). But then It runs fine when it's in the barn. There is a slight hesitation when I stomp on the accelerator.  It only gets squirly under a load.

Classic symptoms of fuel starvation.

The pump is weak or the filters/strainer  are plugged.

They are unable to meet the increased fuel demand of uphill driving.

Fuel pressure drops as you go uphill.

For the hard starting,don`t forget to adjust the choke pull off

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On a vehicle I had,  I messed and messed with the carburetor cause it would run better with the choke part way out or partial throttle.  eventually, I found the coil was the problem.  I'm guessing the choke would lower the compression and let the coil work. I would change the plugs and try a different coil.  (just a thought)

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Was going to pull the fuel pump off one of my other Subaru's that run good to see if that was the problem. When I dropped the pump on this one I noticed that the hose going to the pump was kinked, being too long. So if fuel starving  was the problem, as naru2 said, I figured that could be the cause. I cut off several inches and put the spring clamp where it had been kinked and put it back together, took a drive up the hill and it seemed to run OK.

Has anyone installed a universal fuel pump on one of these guys? I saw one on ebay for $13. The regular Subaru pump was $43 and up. If it's just a matter of changing the electrical plug, that's a good deal. But if they're junk, it's not.

 

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