mule running and idling great but no power?

[savagebrother]

to make a long story short, last fall while down in WV to deer hunt on my way back to my camper she started to miss and finally one cylinder quit. well once home and with here on the lift i began checking the the plugs and plug wires etc. etc. well the right cylinder spark plug was loose, and i mean i took it out by fingers only. i thought well that was difinitly the reason for the miss. well checked the plug gap and cleaned it. bought me a slim or thin wall plug socket and put it back in. well she starts right up warms up and man idles so smooth and at a very low rpm. well now for the problem
when i drive her she takes off good but i have no power is how it feels. like a distributor that has been set far to retarded. so what could be going on???? it was running with plenty of get up and go before. when not under load it revs right up, its when its under load its like the governor isnt working to me?? anyone experience this?? its not smoking or making any strange noises.
any help will be much appreciated.
thanks
SB

 

[NDT]

Maybe the carb jets are gummed up. Try some Seafoam in the tank.

 

[savagebrother]

Sea foam!!!! Well I thought about that too but why would it go to full throttle when it's not under load???
i would think that it wouldn't run at full throttle at all???
See my quandary ??
SB

 

[The Auto Shop teacher]

Trying to diagnose problems on the internet is like doing it on the telephone, you can only throw out ideas of things to check.

There are 3 things needed for combustion, spark (at the right time and a fat spark to ignite the A/F mix), fuel (fresh fuel in the proper amount), and compression (above 100 psi in each cyl). Since you say that the mule ran fine just before you started running bad, I would start by checking the fuel supply for clean fresh fuel getting to the carburetor and the small return line back to the tank. Remember that there is a fuel filter in the gas tank, one at the engine in a fuel bowl before the pump, and another screen on the fuel inlet to the carburetor. Once checked out I would crank the engine to verify that the fuel pump is working pumping fuel to the carburetor about 3 or 4 psi and the return line isn't restricted back to the tank.

If the fuel system checks out, remember that the air inlet cannot be restricted (check air filter for clogging, or oil saturation) as that will choke off air flow to the carburetor. Having checked that, you could pull off the muffler and run the engine to verify the exhaust system isn't plugged.

Start with those ideas and please keep us posted as to what you find. And remember, KISS (keep it simple stupid), to remind you to check the easy things first as they are usually the problem.

 

[snowtrac nome]

shop teacher had some good ideas ensure your choke is open by removing the air intake and looking at it. you realize it could be your timing as a change in point gap or dwell angle does have an effect in timing as well as coil saturation

 

[The Auto Shop teacher]

Thanks Snowtrack nome, forgot to add the choke flap check. Point gap is important, not only does the contact surface of the points affect the amount of spark the coil throws out on the secondary side, but the gap has a big effect on the timing as well. When you change the point gap, you also change the timing of when the spark occurs.

 

[savagebrother]

Yes your all correct, but??? I would think if it was the points that it wouldn't matter whether it was under load or not. Motor revs right on up unloaded. Now I pulled the inline gas filter and guess what?? Yeah no filter. Well, so then I pulled the governor and it checked ok, put it back on. Now I'm pulling The carb to see how much chit is in it. I forgot to check the timing when I took the governor off but since that's easy I'll do that after I get the carb off. Oh I ordered a new carb while I was at it. I will pull the the mag cover and check the the points too. I still can't figure out how the left spark plug worked it's way loose. I literally took it the rest of the way out with my fingers!!! I drove one for 2 years in Hawaii and I don't ever remember spark plugs coming loose. I was the only one that drove it I did all the maintenance on it so I would have known if a spark plug came loose. Anyway I guess I might as well pull the fuel tank and check that filter and the tank.
Man it was running so good before this too!!!!!

 

[Another Ahab]

I still can't figure out how the left spark plug worked it's way loose. I literally took it the rest of the way out with my fingers!!! I drove one for 2 years in Hawaii and I don't ever remember spark plugs coming loose. I was the only one that drove it I did all the maintenance on it so I would have known if a spark plug came loose. Anyway I guess I might as well pull the fuel tank and check that filter and the tank.
Man it was running so good before this too!!!!!

The good news is that all this maintenance won't do it any harm.

 

[savagebrother]

Yes ahah I needed to do all this anyway. It would have just been nice to have done it and knowing it was still running good.
SB

 

[The Auto Shop teacher]

When the engine is under load it takes a hotter spark, (read more voltage out of the coil) to fire the plugs. Remember too that the coil is firing BOTH spark plugs at the same time, the one on the compression stroke is called the 'event spark', the other cyl is the 'waste spark', but they both have to fire to run.

I am of the feeling 'from afar' that your problem is more likely to be a fuel one, but we will see.....

 

[savagebrother]

Yes that was my thoughts too. It doesn't take much gas or electric to run a gas motor that's without a load on it.
Im thinking gas to especially after finding missing gas filter element. The guy I bought it from had had it for 10 years he told me. And he said it was sitting a lot the last few years he had it because he had moved on to other projects.
It didnt idle right and I had to adjust the carb right off and the engine was covered with dust. So.....I'm thinking fuel to, but I'm going to check everything.
SB

 

[The Auto Shop teacher]

Don't forget to check the screen in the fuel inlet to the carburetor. If you are missing the other two filters, there is a good chance that the little screen is clogged with debris as it wouldn't take much. Here is a link to some good information about the fuel systems filters. http://g503.com/forums/viewtopic.php?f=148&t=205307. If you scroll around, you will find other information about the magneto as well.

 

[The Auto Shop teacher]

Don't forget to replace all of the fuel with fresh gas as this crap we buy today has a short shelf life. You can almost us it to put out fires after sitting a year......

 

[savagebrother]

Yes I have a grass airfield just 4.5 miles up the road from me and he doesn't have a problem selling me some AV gas
SB

 

[The Auto Shop teacher]

Your lucky about the Av Gas as out in Southern Calif. I asked one of our general aviation fields about buying 100LL for the Cessna 172 we have at our school. The manager told me "he could only sell me gas if he pumped it into a wing". I called him on it and said I would bring in a wing from the plane in my truck and where do I park it, and he started retracting his statement......

 

[Another Ahab]

Your lucky about the Av Gas as out in Southern Calif. I asked one of our general aviation fields about buying 100LL for the Cessna 172 we have at our school. The manager told me "he could only sell me gas if he pumped it into a wing". I called him on it and said I would bring in a wing from the plane in my truck and where do I park it, and he started retracting his statement......

Is that a reg of any kind, or is the guy just mouthing off?

 

[snowtrac nome]

being in ca could be a state reg also could be conceived as tax evasion as av gas has no road tax just like heating oil in a diesel or marine gas in a vehicle. in reality who cares if you buy av gas you pay airport tax and marine tax on marine gas I suppose its all about who gets the dough

 

[The Auto Shop teacher]

I suspect he was blowing smoke up my tailpipe, but considering how many people get sued nowadays, it is probably a lot easier (and safer) to say no than use common sense and sell me some.

 

[savagebrother]

We still have work to do on overtaxation
SB

 

[mulman7]

Did you get the engine running correctly? If not then check the following:

1-Compression 110#-125# If one cylinder usually the one furthest from the blower is 0# then pull the valve cover and check the position of the exhaust valve it will be much lower than the intake valve. Rats and mice build nests on that cyl and air flow is stopped causing the head to overheat and the exhaust seat comes out holding the valve open. Replace with a new head. The only ones generally available are genset heads and they do not use the copper head spacer. The genset valve will be even with the valve rotator. The mule valve will be 0.050" above the valve rotator.

2-Check the heim joints on the control rod between the gov and carb. If frozen then the carb will not open properly.

3-With the ign switch off remove the fuel return line from the carb tee and crank the engine to determine fuel flow. fuel will discharge about 1-2 feet.

4-Check the inlet screen on the carb. I remove the carb by disconnecting the heat riser pipes then slide the intake boots to clear the intake manifold and pull the carb, intake manifold and heat riser pipes as one unit. This makes pulling the carb easier then pulling it off the intake manifold when attached to the engine.

5-Check magneto timing that it is 18 degrees advanced engine running 1000-3000rpms. Points set at 0.016". With mag out install the ignition wires and hold them 1/2-1 inch apart to check spark. It should be a bright hot spark. Then short 1 lead to the case and hold the other close to the case and impulse the mag then switch leads. This will verify both wires fire.

Before pulling mag with governor removed check location of timing marks [V] on the mag gear to the cam gear

6-Pull the fuel tank and check filter. This is the hardest step that is why I listed it last.