Engine won't idle, runs like crap
Posted: Mon Aug 15, 2022 12:45 pm
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.