Coleman Powermate 8750 Generator

[pmpmstrb]

Just picked up a used Powermate Generator, model PM0647000. I haven't been able to find much info on it. I had a couple questions on the operation of it. The previous owner, for reasons unknown, clipped the wires for the auto idle solenoid/actuator "A". I can get the unit to start and Idle with choke in and rod "B" held to the left. If I release the rod the engine wants to die unless I pull the choke out and then it runs at full speed. I assume this is normal operation for a unit without the auto-idle function and a simple tortoise/hare lever? That being said

1- Is this normal operation for a non-auto idle unit?
2- Is it safe to operate the unit in this manner?
3- Can I safely convert this unit to propane with it operating in this manner?

The intended use of this unit is for emergency power over the winter for any power outages. Thanks in advance

 

[Cujet]

Strange about the idle. I have to wonder if the carb is dirty. Possibly the idle jet is clogged.

Is there a reason that you are not returning it back to it's original configuration with the auto-idle system working as intended?

The propane conversion kits typically use the original carb's throttle body and governor. They simply replace gasoline with metered propane. I'd bet you can set it up as a normal generator with both a functional carb and functional propane conversion. With or without the auto idle.

 

[JimPghPA]

It sounds like you either have a clogged idle air hole on the carburetor or a bad float bowl gasket (leaking air). The idle air hole is either on the air inlet side of the carb, by the gasket that connects the carb to the air cleaner (there will be a notch in the gasket for the idle air to get into the idle air hole), or it is on the floor of the air inlet to the carb just behind the choke plate, it is a very small hole. For the gasket for the float bowl, "Parts tree" is a good internet site for parts such as gaskets.

BTW, Coleman Powermate generators were made with several different engine manufacturers, such as Briggs and Stratton, Tecumseh, and Honda. Honda engines are the best. They will run for thousands of hours, and they are fuel efficient.

 

[JimPghPA]

BTW, propane is a dangerous gas to work with. If you have it leak into a building such as a garage or a house, it can easily cause a major explosion. Just yesterday there was a tv news clip about a house that did not have natural gas, but did have propane. That house blew up with such a powerful explosion that it was heard three miles away. Propane is heavier than air and if there is a leak it can accumulate in low areas and ignite from such things as a gas water heater, or a gas furnace.

 

[JimPghPA]

Also, there are gas alarms that will detect leaking propane and sound an alarm. Propane is an odorless gas, so if you are piping any of it inside of a building you might want to get a gas alarm that works with propane.

 

[HerrStig]

TO be sure it's "safe" you ought to run it with a load such as a space heater to see if it will hold RPM. It does sound like clipping wires was easier for the prior "generator expert" than cleaning the carb. I priced a new carb for my GC 160 mower when it was acting up and a new one was about 20 bucks, but some Berrymans cleaner fixed the problem which was no doubt some gum in the low speed jet circuit.
Propane conversions can mean buying a new dual fuel carb or just a "spud" threaded into a hole tapped into the existing carb body in which a metering unit is installed. Either way, I'd run it outside.

 

[Quest]

As these Honda engines are designed for gasoline, watch out for valve seat recession when converting to propane.

Exhaust valve may wear out far sooner than running gasoline, mind you.

Q.

 

[pmpmstrb]

Originally Posted By: Cujet
Strange about the idle. I have to wonder if the carb is dirty. Possibly the idle jet is clogged.

Is there a reason that you are not returning it back to it's original configuration with the auto-idle system working as intended?


I would love to return it back to original but have had zero success in finding any kind of parts/schematics/etc on this part for this model. I have found multiple schematics, but they are all the same in that none of them show anything having to do with the auto-idle system. I don't even know where the solenoid wires would go if I could even find one.


As for the other replies, I apologize. I was a little rushed in typing my first post. Kids can be a little distracting. Here are the details I missed.

Rod "B" is spring loaded to the right. That's why it wants to rev higher when I let go. Which brings me to the choke. When it revs higher it feeds more fuel which needs more air. Pulling the choke opens up full air flow. Am I correct on my thinking here? I don't think it is a clogged/dirty carb. I just think that it's a half converted auto to manual. So I either need to try and restore it to original or make sure that converting it to full manual will allow it to operate properly. I am unsure if the auto-idle takes the choke plate into account and opens it on demand of load or not. That is something I will have to look into tomorrow as well as removing the spring from the rod.

 

[Cujet]

The spring loaded rod is the governor. It controls engine speed to 3600 RPM as closely as it can. Pulling on it closes the throttle and lets the engine idle.

At no point should the choke be necessary with a properly functioning carburetor and a warmed up engine. The choke should only be used for cold startup.

Yes, you can operate the generator without auto idle. It will simply start and operate at 3600 RPM. I had guessed that the wires were simply cut, from your first statement.

I can understand why auto-idle may be undesirable if clean power is necessary.

 

[cat843]

Auto idle is fine for a job-site so when you turn on a saw, the generator jumps to 3600 RPM.

But for powering your home there are always some devices needing small amounts of power (clocks, controls for refrig or heat) and the only way they will get 110V (or 220V) and 60 cycle is for the engine to run at 3600 RPM. It will not be fully loaded, but must run at full RPM.

 

[gainestruk]

Originally Posted By: JimPghPA
Also, there are gas alarms that will detect leaking propane and sound an alarm. Propane is an odorless gas, so if you are piping any of it inside of a building you might want to get a gas alarm that works with propane.


I take it you haven't been around propane, yes it's odorless when it comes out of ground but they add mercaptan to give it a very strong smell.

Propane is no more dangerous than natural gas, we have used it for heating and cooking for all of my 55 years, yes it will settle to low area but I guarantee you will know it.

 

[b4hntn]

I have the EXACT same Coleman Powermate 8750 Generator. I looked at you place marked "A" on mine and wires are cut at the bottom of the boot on whatever that thing is. I also bought it used. Previous owner used it in a boat with zillions of light to bow hunt gar. Sold it because it took four to load it in the boat. I can't imagine why he would need it to idle so this may have been a factory "option."