Engine won't idle, runs like crap

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pinzinator
Posts: 917
Joined: Thu Jul 29, 2004 3:12 pm
Location: Indio, California

Engine won't idle, runs like crap

Post by pinzinator »

I hadn't driven my Pinzgauer in a while and had to haul some tires to get mounted. It didn't want to start, and when it did the idle was terrible, like hitting on 2 cylinders. Like many other PinzSSI owners my first thought was to blame the ignition and call the business for an instant free diagnosis. But then reality set in rather quickly when I realized that I would just be talking to myself.

The ignition was quickly ruled out as the problem. Simply disconnecting plug wire 1 and then reconnecting, then disconnecting plug wire 2 and reconnecting verified that the engine was hitting on all 4.

Fuel pressure was perfect at 3 PSI.

I verified the float level, and noticed that the rear carb was about 5mm high. After removing the bowl cover I cleaned out the 4 air jets in each carb with a wire and carb cleaner and the engine suddenly ran a lot better. But not good enough.

Next I adjusted the needle valve on the rear carb by adding a .5mm washer to lower the fuel level, and it dropped so far that the engine would not idle. So I took the top back off and removed the float, and it was saturated with gas so badly that it sloshed when shaken. I'm surprised that the engine ran at all! The front float was OK, but since I was ordering one float I might as well replace both, as the front could start leaking at any time. I don't know how old the front float is, but know that it is at least 20 years old. Remember, a float is called a float for a reason. In this case it turned into a sink.

Perhaps someone may have an idea as to why an engine with a bad float would suddenly run better with the air jets cleaned? My recommendation to anyone reading this is to pull the air cleaner and clean out the 4 visible air jets in each carb throat with a tiny wire and carb cleaner. It takes longer to remove the air cleaner than to do the actual job, it's that easy.

I bought the new floats from Expedition Imports. You may want to check yours if the engine idles rough and won't tune. If you buy a new float be sure to buy a few adjustment shims and float tool at the same time, in case you have to adjust the float height.

The ideal float height is 18.5mm below the bowl gasket. If you measure a 21mm float height, add a .5mm shim to the base of the needle valve. The float height will LOWER by a factor of 4, which means .5mm shim will LOWER the float 2mm, a 1mm will LOWER the float by 4mm. By adding a .5mm shim the float should lower to 19mm, which is within specs. To RAISE the float level REMOVE shims with consideration to the same 4-1 factor.
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Here you can see that the fuel level is high on the rear carb. A saturated float that sinks will allow too much fuel into the bowl.
The fuel should be level with the metal that is even with the wire that actuates the choke. +- 1mm.
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These are the 4 air jets in each carb that you can clean with a tiny wire and carb cleaner. DON'T force a large wire in to do the job.
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The needle valve is adjusted by adding or removing shims from where is seats against the cover. Adding shims lowers the fuel level. 1mm thickness lowers fuel 4mm.
It takes a special size shim, these are not readily available at a hardware store, but you can try.
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A saturated float will be heavy and slosh when shaken. This cannot be drained.
Per the repair manual the float should not be adjusted by bending the tab, like on some carbs.
Last edited by pinzinator on Wed Aug 24, 2022 9:28 am, edited 5 times in total.
whitesik
United States of America
Posts: 223
Joined: Thu Apr 02, 2015 2:11 pm
Location: Indiana, U.S.A.

Re: Engine won't idle, runs like crap

Post by whitesik »

Thanks for the good info. I may just order some spare floats to have on hand. I have a question about your method of checking to see if cylinders are missing however. You preformed what I consider the usual method but I thought with the PinzSSI one was not supposed to attempt starting or running with a spark plug disconnected. Something about damage to the electronics. Please educate me further.
75 Swiss 710K
Not so new owner but still a novice
W9YG
pinzinator
Posts: 917
Joined: Thu Jul 29, 2004 3:12 pm
Location: Indio, California

Re: Engine won't idle, runs like crap

Post by pinzinator »

You can verify whether or not the coil is firing by disconnect wires 1 and 2 individually. Don't do this with 3 and 4. Running the engine for a few seconds will not damage anything, but running a few miles will. That is why a spare spring is included with a new ignition. The wires will not come off if properly installed. If you lose a plug wire you immediately lose 2 cylinders and half the power of the engine.
When testing like this the voltage is so high that you will immediately hear the arc of the spark jumping. DO NOT lean against the vehicle when doing this, use only one hand. Keep the other hand off of the vehicle.
Just reach up and shut the engine off after hearing the arc, don't try to reconnect while the engine is running. Let go of the plug wire and use the same hand, not the other hand, to turn the key. You DO NOT want to create a potential path for shock.
Or have someone else shut the engine off.
Or loosen the plug wire first and start the engine, you will hear the arc. Whatever method works for you, just bear in mind this is high DC voltage.
pinzinator
Posts: 917
Joined: Thu Jul 29, 2004 3:12 pm
Location: Indio, California

Re: Engine won't idle, runs like crap

Post by pinzinator »

I got the carbs back together and the engine is running great once again. I ended up replacing the top gaskets, too. If you ever order top gaskets, order 4 of the tiny pins that hold the gasket in place, just in case you ruin or lose the old ones. Don't use gasket sealer on either side of the top cover gasket!
I found that it is much easier to measure the fuel level right in the bowl itself, which should be 18.5mm. With 2-1mm shims behind the needle valves I was able to dial both carbs in at the correct level. Then it was a matter of re-assembly and balancing the carbs. Fuel pressure checked in at about 3.25 PSI.

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rear balance.jpg
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front balance.jpg
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