Generator Question

[Country]

I have an 8000 watt, or is that volts, generator that I have had for over 10 years. It has a 16 HP Briggs & Stratton engine.

I was getting it ready for winter by changing the oil and filter and found that the fuel pump had a leak. I had the gas turned off at the gas tank and didn't know about the leak until I turned the gas on. Glad I found that before I needed the generator in the middle of winter.

There are two holes in the pump body but they never leaked before. I took the old pump with me when I went to the dealer to get a new one. The service guy said that there must be a diaphragm in there that eventually shrinks and allows gas to get to those holes.

This generator has a fuel shutoff between the fuel tank and the fuel pump. As long as I've had this thing I have shut the generator down by turning off the fuel supply so the fuel pump and carburetor run dry of fuel and shuts down and then I put it in the garage for storage until I need it again.

I figure since the generator sits in storage for long periods if I run all the gas out of the carburetor then it is not as likely to gum up versus leaving the fuel pump and carburetor full of fuel to eventually evaporate.

So is my thinking about that right? Or does it really matter at all?

David

[Molly Brown]

Your thinking is correct but the real question you should be asking is why doesn=92t the diaphragm or similar rubber part in your car or truck shrink. Just because something is made of rubber doesn=92t mean that it can stand up to gasoline without deteriorating. The chemical composition of all rubber is not the same. So the diaphragm should not have shrunk in the first place and who is responsible if it did?

[A. Baum]

Probably a fuel filter. Those motors don't typically have a fuel pump since the carburetor is gravity fed. You local small engine shop should sell a replacement for a few bucks.

[ransley]

I have a 7500w, 15 hp Generac, it has a fuel tank on top and no pump, I never saw one with a pump that had the tank on top, there is no need for one.

[willshak]

Country wrote the following:

I just shut off the generator and then close the fuel valve. Could it be the diaphragm/gaskets dried out? Since power failures are quite common in my rural area (power lines running through roadside tree branches), I run the generator on occasion just to get things moving before I really need it.

[Frank]

That's what I do. I think I have same generator as op but more recent model.

[LSMFT]

If you have a diaphragm? and a pump? Sounds more like a stuck needle valve overflowing the carb bowl. Running it out of gas does not mean the carb is empty. Some gunk still forms in there. It would be better to change the fuel in the tank once a year and run it for 15 minutes to get fresh gas through it. Use the old gas in your lawnmower or garden tractor.

[Country]

Yeah, he was probably just guessing. I don't think he knew for sure.

[Ralph Mowery]

I think it is more of what is called long term storage. If this is going to be 6 months or longer then you may want to drain the gas and run the motor long enough to starve it of gas. That is similar to what most manuals say. Also pull the spark plug and add oil to the cylinder and replace the plug. If less then I would just start it about every 2 weeks and let it run for about 10 minuets.

I bought a new 5 kw generator about 10 years ago and opened the box to see what it needed to get it going. closed up the box for a year. Put in the oil and gas and it started up. Ran it for a couple of hours when the power went out. Drained the gas and about a year later it started fine when I needed it. This time I did not drain the gas and had other things going on so it just sit. Would not start about a year later . Carburetor gummed up. Cleaned it out and all was fine. That happened twice. Now I put in the Sta-bil in the gas and start it up atleast every 3 weeks. It will usually start with 2 or 3 pulls just as it always did when new. I think it is even more important not to let the gas sit too long with out the Sta-bil as it has that junk called ethanol in it. Or however you spell it.

[Country]

This one has three lines. One from the fuel tank, one to the carb and one to the crank case. Since there are no electrical hookups, I assume it is vacuum driven.

This engine is amazing. I had not started it in months and after I got the oil changed and put on the new fuel pump, I found that the battery was dead and needed to be replaced.

I had never tried starting this engine by just using the pull start so I thought I would give it a try. One pull on that thing and it started right up. And it pulled so easy. Wow!!

[Country]

I agree that there seems to be no need for one. The fuel pump was leaking with just the gravity feed to it. I didn't start it until I had the new fuel pump on.

[Country]

The problem is not in the carburetor. It was the fuel pump which is a separate unit.

Thanks, David

[hrhofmann]

Many of the responses seem to believe that the fuel tank is above the carburetor and that there is no actual fuel pump, just some sort of a regulator for the fuel leel in the carburetor. There scould be a pumping action based on the alternate pulsing of the crankcase ventilator if a pump were needed. Can the OP please state where the gas tank is located with respect to the carburetor.

[ransley]

What make and model is it

[Country]

The fuel tank is above the engine on this unit. The part that I replaced is called a fuel pump. How much actual "pumping" it does, I do not know.

It was a pretty easy fix replacing the pump. It cost just under $30 for the part.

[Country]

It is a PowerBoss 8000 made by Generac by Briggs & Stratton Power Procucts.

[A. Baum]

No need to be vacuum driven. It has a emission control system that feeds crankcase vapors back into the intake.

Compression release. The Kohler Commander motor in my John Deere tractor has one. The 6.5 horse on my leaf vac/shredder/chipper has one. The motor on my John Deere 59cc chain saw has one. The saw is almost impossible to pull if you don't push the compression release before trying to start it.

Hope you got all your issues answered. I've owned a 5kw Brigs powered generator for 15 years. Used it once in 2002 when a tornado took out a substation nearby. Took 3 days to restore the power. This generator Generac isn't the most fuel efficient. Consumes about 1.5 quarts per hour.

[ransley]

I have a 7500w generac, that 3rd line is probably to recycle gas vapors into the crankcase, my tank is on top, with a tank on top you dont need a pump, thats why they are on top. That leak must be the carb, check your oil level, Ive seen Generac float valves stick and completely flood the motor with gas, but even a bit ruins the oil so be carefull if its flooded, it can thin the oil so you motor is ruined from lack of lubrication with thined oil. My friends generac was so flooded it wouldnt pull, when we took out the plug and pulled the rope gasolene shot out 10 ft. And it flooded like that overnight from a stuck float valve not closing, Thats why shutting off the gas after every use is important. Check if you have a fuel filter, my 7500 xl didnt come with one, which it dumb, it has everything else and the crap from the bottom of the tank goes right to the carb and screws up the small jets and openings.

[Country]

Hi Ransley,

Thanks for trying to help but I already had that problem fixed when I posted the OP. There is fuel pump on this thing and it was leaking which is why I replaced it. My reason for the OP was to inquire about whether to continue shutting off the fuel supply and running the carburetor dry of fuel when I go to shut the generator off after use.

[Country]

Like I said before, that is what it is called. Exactly how much pumping it does, I don't know.

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