Generator question...

[Phoenix78]

In an effort to get my very small generator to run through the night without a refill I disconnected the fuel line from the tank and adapted a 6-gallon boat fuel tank and line to the generator.

It runs fine. Does anyone see a problem with what I've done? My wife will not be very happy with me if I blow something up - again!

Thanks! ...Alan

[SkywarnKR4YO]

As long as your fittings are sound and without any leaks you should be good to go, and hopefully you didn't use any gas-soluble types of tubing in your fuel plumbing.

There is another issue here though -- another reason for a small tank is that it (theoretically) forces you to go check the machine every so often. I'd keep a good tally of running hours -- back in my Army days I regularly worked with/on both small 3 to 5 kW gennies as well as the larger diesel units (what I think of as a "commercial" generator). The small gas-powered units are definitely designed for intermittent service, thus the need to keep up with the tight (usually 20-25 hour) service interval. We usually ran two machines in an alternating 4 hour (a tank of gas was usually good for about 5 hrs) on/off cycle, which really minimized breakdowns, particularly in the electrical side of the machine. It seemed that the fact the electronics got hot was not so much a problem as the duration of the cooking. We got more total running hours between failures doing it this way. The commercial machines, designed for continuous service, had a much longer interval between maintenance periods. Of course, we are talking lawn mower engine vs. diesel truck engine here...

Few of us can probably do the alternating-machine trick, though. With the small tank, if you're refueling safely (i.e. letting the machine cool before sloshing gas into/over it) you're at least getting a little down time. Admittedly, you've also got no power, but if you don't have a life-critical need for power (and if you did I hope you'd already evacuated), I'd be willing to tolerate a known hour without juice while I pulled some preventative maintenance. Beats the hell out of the feeling you have looking at a generator that has suddenly become an expensive but ugly lawn ornament trailing an orange extension cord.

Good luck with the machine -- and don't forget to stock up on oil, plugs, etc. I do a lot of emergency preparedness work as a ham radio operator and it seems that something goofy, like a cracked spark plug insulator, always happens at the most inopportune time. I've learned never to regret spending some extra bucks on spare parts for equipment I specifically buy for use in troubled times.

Didn't mean to lecture- just wanted to share some lessons learned. Stay safe, and may Mr. Murphy never favor you with his presence.

[Phoenix78]

SkyWarn... Thanks for the reply - your "lecture" was exactly what I was looking for! The genny is a 2500 watt Colman - runs a 5,000 BTU AC and fan very well. I use Mobil1 and it runs fine!

I like it because it sips gas!

I'll be sure to give it plenty of down time.

...Alan

[Phoenix78]

Hummm... maybe this gas tank modification wasn't such a good idea. I hooked up my copper tubing set-up to the boat tank, pumped-up the bulb and let the genny rip. Wouldn't run smooth until the bulb was firm and the filler cap was tight. After about 10 minutes of smooth running the idle got real rough so I squeezed the bulb again and the idle evened out. This went on a couple more times until I said "forget it" and just let the engine die.

Looks like it doesn't like the "bulb" set up. I'm thinking of just setting up a gravity-feed system.

What do you think?

...Alan

[LSU2001]

I think you need a gravity feed. Small generator motors probably don't provide enough suction to keep the fuel flowing through the bulb. Try placing the tank above the genny to see if that helps.
TIm

[HurriCat]

An' be putting that American Muscle ride of yours safely inside the garage, too! (Muscle Cars... they DO exist!)

[Phoenix78]

Oh well... I guess I'm gonna throw in the towel on this one! I rigged a tank to gravity feed the generator from a point about 12" higher than the carb. Started right up, ran for about 3 minutes and died.

Wouldn't restart - even after mulitiple attempts, letting it sit, and multiple choke settings.

I disconnected the external tank, reconnected the genny's tank and it ran fine for 15 minutes before I shut it down.

Anyone have any ideas before I abandon this project?

Thanks! ...Alan

[SkywarnKR4YO]

Out of curiosity... how is air getting back into the fuel tank to replace the volume of gas that has been lost? My guess (just a guess) is that your failure to achieve fuel flow is due to vacuum in the tank. Atmospheric pressure will hold up a 33 foot column of water -- 12 inches of gas (at 5/8 the density of water) is nothing...Back of the envelope calculations tell me that under 1/3psi of vacuum will lock up the system.. The bulb has a valve to allow air in, but stiff enough to not allow gas leakage in normal operation and the higher suction of the boat engine is adequate to cause it to open. The genny carb, being designed for gravity feed, won't do the trick. My guess is the tank you rigged for gravity feed isn't vented and that's why you got about 3 minutes worth until the thing vacuum locked (and why squeezing the bulb got results before -- the bulb suction allowed the valve to open and equalize pressure). I bet the gas cap on the genny is vented in one way or another, probably with 3 or four perforations in it and a shield to prevent gas from splashing through the holes due to normal movement and vibration. If the gravity-feed line rises at any point above the level of gas in the tank, then drops down to carb level, you essentially have a siphon, which will work, but can't have any air bubbles in it.

Best bet is a gravity feed tank, with fuel outlet on the bottom, and a vented filler cap on top -- basically a big detached version of the genny tank itself.

Hope this helps.

[Phoenix78]

Skywarn - Thanks for the detailed response.

I had never really given much thought to how the volume taken up by the gas would be replaced. The boat tank is not vented (when the cap is removed you hear a slight "whoosh" as air escapes - or rushes in - not sure which). So - what you're saying is the genny had a classic case of "vapor-lock". I've always heard of it but never experienced it!

I'm using an old tank - drilled a hole on the bottom and installed copper and brass fittings, to which I've attached rubber fuel line running to the genny carb. The tank sits a foot above the carb. What your saying is all I need to do is slightly loosen the gas cap and I should have no problems - right?

Thank-you for your interest and response. To all others - maybe our correspondence will help you too increase your generators fuel capacity once we get these kinks ironed out!

...Alan