THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

Checking the carbs before rebuilding them found fuel dripping in a venturi in the rear carb. Continued to drip for a while after turning the engine off.

Drip looks just like audiocontr's video. I took video but didn't turn out.

Once we changed the chokes to being fully closed rather than 1/2 open, rough idle, almost died. Rich exhaust smell.

All shutoff solenoids click when power is applied.

Checked float levels and the front was +3 mm, but the rear was +16 mm!

Synch was off with front at 10 and rear at 14. Throttle linkage wasn't balanced.

Adjusted idle stops, idle fuel mixture (they were OK), carbs synch'd equal, and got a smooth idle at decent rpm. Less rich exhaust smell.

Rebuilding the carbs tomorrow, anyone have an idea why the rear one is dripping fuel even after shutoff. Interested to know what to look for.

Checked float levels and the front was +3 mm, but the rear was +16 mm!...Rebuilding the carbs tomorrow, anyone have an idea why the rear one is dripping fuel even after shutoff. Interested to know what to look for.

I am assuming that you have not corrected the float levels yet, but 16mm too high will always result that the fuel level in the bowl is higher than the orifices in the venturi; hence the fuel drains out after shutoff. Obviously that carb is much too rich under those conditions. The float valve is damaged and won't seat, the float has sunk, or similar problem.

Jimm391730 wrote:

Checked float levels and the front was +3 mm, but the rear was +16 mm!...Rebuilding the carbs tomorrow, anyone have an idea why the rear one is dripping fuel even after shutoff. Interested to know what to look for.

I am assuming that you have not corrected the float levels yet, but 16mm too high will always result that the fuel level in the bowl is higher than the orifices in the venturi; hence the fuel drains out after shutoff. Obviously that carb is much too rich under those conditions. The float valve is damaged and won't seat, the float has sunk, or similar problem.

Thanks Jimm391730. I ordered some new floats from SAV today just in case. We haven't tried to correct the float level since we were just testing the existing situation before we take the carbs out and rebuild them. We'll be doing that on the bad rear one tonight and we'll know more then. We have the SAV rebuild kit and although their description of what is in it is very poor, it does have a new float needle valve.

We have the high level carb apart now. The needle valve appears to function well just like the new one in the kit. The float looks fine, no damage.

We haven't dipped the carb yet or put it back together with the new kit parts.

I have new floats on the way, but how to you know if the old float is OK? My brother says he used to weigh his on other vehicles but we'd need to know what the OEM float weight is. Any suggestions?

bbolander wrote:I have new floats on the way, but how to you know if the old float is OK? My brother says he used to weigh his on other vehicles but we'd need to know what the OEM float weight is. Any suggestions?

Don't you have two? Weigh them both. :idea:

undysworld wrote:

bbolander wrote:I have new floats on the way, but how to you know if the old float is OK? My brother says he used to weigh his on other vehicles but we'd need to know what the OEM float weight is. Any suggestions?

Don't you have two? Weigh them both. :idea:

Great idea!

We also found the accelerator pump not attached to the lever with any clips in the suspect carb. When we pulled off the top cover, the accelerator pump was still down in it's tube. That possibly could have happened when we removed the cover, or maybe it wasn't connected to the lever at all.

We don't think that would have anything to do with the high float level or the dripping gas though. Are we thinking correctly?

Did you shim the rear needle valve to lower fuel in the bowl yet?

audiocontr wrote:Did you shim the rear needle valve to lower fuel in the bowl yet?

Not yet, because the needle valve only had one washer on it, same as the front carb that had a good level reading of +3mm. I do have extra .5 and 1mm shim washers just in case. The culprit rear carb float does feel heavier than the good level front carb float. I'll be weighing them and also the new ones coming in next week for a comparison. So we'll see how the float levels turn out after the rebuild is done with new floats. Waiting for parts for a few days now and will get back into it later next week.

The needle could wear differently resulting in a need for a shim or two extra. Mine do not match.

Got the new floats delivered from SAV today. Both new floats and both old floats weighed 1.0 oz on my postal scale that measures to the 0.1 oz accuracy. So our flooding problem must have been something else, maybe a sticking needle valve.

Since the good front carb level was +3 mm with one washer, probably putting an extra 1 mm washer on each needle valve would be a good starting point.

Won't be trying to run it with the new carbs until this weekend.

Please remember that you do not need equal washers per carb. Its perfectly acceptable to have different values... try this: Swap needle valves. Do the values change?

Thanks on the different washers. We're using new needle valves from the SAV kit, not the old ones.

We completed the carburetor rebuild tonight, started up the Pinz and it went perfectly. No more fuel dripping in the carbs before or after shutoff. Fuel levels were perfect on both carbs with two 1 mm washers on the float needle valve. We did that based on a Porsche article that said 0.728" from the top plate joint to the meniscus - so we assumed that was to the tip of the needle valve. The kit came with a 0.5 mm washer, so we discarded it and put in two 1 mm washers. Both float readings were right on the money. We didn't even have to remove the top cover once to adjust washers. We also synchronized the carbs and got them to a reading of 10 on each one. Runs very smoothly and no more exhaust smoke or smell.

Thanks for everyone's help. A very successful rebuild.