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I've got a 71 pinz that idles around 3000 rpm's. have cleaned carbs and checked solenoids and choke.
Can see fuel dribbling past venturies adjusting mixture screws does very little idle screws are useless.
linkage disconnected and throttle plate and shafts seem straight and tight. Can look down carbs and see butterfly's closed
all the way around them.
Had to clean/rebuild carbs because of acell pumps not working and even at high idle it stalled when tried to acell.
Now pumps functional still had high idle.
Any ideas would be helpful.
Thanks Mikel

I just finished replacing a fuel pump that had a bad internal valve and was allowing too high pressure to the carbs. The carbs were getting flooded and the idle and running were both out of wack. Replacing the pump solved the problem. Just a thought to consider.

Interesting, wouldn't happen to know what fuel pressure should be? it would be easy enough to test, most carb vehicles that I have messed with should be around 4 to 6 lbs. It does act like its trying to flood, just can't get my head around the super idle but these are set up different than any I have messed with before with the 4 solenoids so anything's possible.
Thanks for the new direction.
Mikel

I seem to remember hearing that 3.5 was the correct number but not sure about that. Hopefully someone else will chime in.

edit: Just looked in the service manual and it mentions the pump should supply .3 bar at 4000 rpm - .3 bar is approx. 4.3 psi. Does that sound correct?

That sounds about right, thanks for checking I will check it Monday morning, its funny you said flooding carbs before I left the shop tonight the back carb was flooding I think I need to also reset the floats. I check the levels but instructions were a little weird so I'm going to double check them, they were set by last person who rebuilt them.
Thanks again.
Mikel

Excessive fuel or not, I find it hard to believe that it runs no slower than 3,000 rpm without a significant vacuum leak. Without air, the engine just can't turn that fast or consume excessive fuel. I'd check the carb bases at the throttle shafts, manifold bolts at each end, check to see that the balance hose (under the air tin) has not deteriorated.

Thanks Jim I'll check that as well, I was thinking vac leak also but have not been able to locate any ...yet.

1.5-2.5psi fuel pressure

Well guys I have about lost all hope, I checked fuel pressure, it fluctuates between 1.5 and 3 psi, checked then removed all vac lines and equalizer tube even capped them off, removed intake manifolds cleaned and pressure checked for cracks, nothing. Pulled carbs apart again checked linkage rods and butterflies closely, rods seemed tight and butterflies were tight and centered everything checked fine or made no difference to the idle.
WOW, I haven't had this much of a problem with a carb in twenty years.
I have run the pinz with the solenoids disconnected completely and disconnecting them one at a time and idle does get lower then dies, I can make it run without them but its very unhappy. It seems like I have a substantial vacuum leak below the butterflies but I absolutely cannot figure out how the choke actually works and it seems to be the most likely suspect but when it put my fingers in the holes while its running it doesn't make any difference. I think its below the butterflies because I cannot see enough fuel from the venturi's to make it idle this high hitting the closed butterflies.
Does anyone know if the really rough passages in the choke areas are normal?
Can anyone explain how the choke system works on these carbs? I feel really stupid having to ask that question but I have run out of idea's. Thanks Mikel

Hey guys I was just reading another thread and he mentioned he thought his floats were set to high or stuck because he had a high idle, can floats set to high cause a high idle on these carbs?
I can r&r the carbs again and try to figure out how to set them if its possible.
Thanks Mikel

Are you sure both chokes are off? The 2 choke levers should be as forward as possible, towards the front of the vehicle (they are on the passenger side of the carbs). The Zenith carb does not choke with a butterfly like older American cars. It adds extra fuel through a choke jet.



The lever on the side of the carb facing you should be at about 2 o'clock for the choke to be off. As you see it here at the 11:30 position the choke is about half on. The Pinzgauer WILL idle at 3000 RPM if both chokes are on, even partially.

They are all the way forward, two o clock, but since the carbs have been overhauled by ....questionable tech's? I don't know if the three different size holes are lined up correctly. It seems like the lever and plate have been separated at some point. I can see through the carb body and when the lever is at 2 o clock the largest opening is over the space in the body, when pulled back small circle opening moves into carb body opening. I don't know if this is correct or not. If I open the choke while running it idles up slightly then goes back down to 3 k making no noticeable difference. Question: Do you know if the solenoids allow air or fuel to pass through them? I thought fuel (fuel cut off solenoid) but I don't know for sure.
Thanks again,
Mikel

Also on the other side of carb (in pic) is a square plate covering four (jets) two larger than the other two do you know if the larger ones are on top or the other way around?
Mikel

You may be onto something with the fuel bowl level. Could it be that your shut off valves (or one of them) may be not seating properly and even with properly adjusted floats you are getting too much fuel.

After sitting overnight does the truck start at the high idle speed and stay there or does it start normally and then speed up? With correct pressure and float height speeding up would point to fuel needle valves.

Another thought. I had a similar problem with a float that had a hole and would sink. If you have the floats out again it may be worth checking. I don't know if these are solid or hollow. I haven't got there yet with my truck.

Have the jets only been blown clean? Mechanical cleaning could have damaged them and effected their operation.

That's all I've got. Good luck.

Yet another thought,

Try reconnecting all of the linkage and without starting it pump the pedal 2 or 3 times. If something is just sticking it may free it up and allow the springs to shut everything down to normal.