Auxiliary Gas Tank for Generator - How To Add?

I have a 7000W portable generator that we use at our house for backup power when the electricity goes out. It contains a 5 gallon tank that sits directly above the generator and gravity feeds to a Honda GSX390 13HP engine.

I would like to hook up an external, auxiliary gas tank to the generator so when the power goes out I don't need to make sure the gas tank is re-filled every 5 or 6 hours. However, as the present tank is gravity fed, I'm not sure the best way to hook up an external tank. I was looking at a vented 18 gallon aluminum model but have read that gravity fed systems can be dangerous should there be a leak.

Does anyone have any suggestions? The cap on the original gas tank is one of the float variety that measures the amount of fuel in the tank based on the float and there is a gauge under a plastic bubble on the top of the cap. I've seen some setups that use a marine gas tank and a siphon system but that requires one to drill a hole in the top of the existing gas cap and install a fitting. And I think that type of a setup involves a smaller generator that may actually contain some type of fuel pump? Again, and suggestions or ideas would be appreciated. I don't want to try something and either end up with a huge fuel spill or possibly worse. Thanks.

 

bump. anyone??????????????????

 

Give it time..give it time...some folks have jobs..unlike me..but i have no advice.......

 

I have a Honda 1000 and here is what i did.

I removed the line going to the current tank and hooked up a 7 gallon tank. I used auto gas line (neoprene) and also placed an in-line valve to control the flow to the generator. I drilled a hole in the 7 gallon tank about 2" high from the bottom to avoid any contaminates that might get in the large tank. I attached a connection at the tank with a double sealing attachment from any hardware store (make sure it is gas safe). I attached the line where the OEM line attached to the carb and held it in place with a hose clamp. I then placed the large 7 gallon tank above the generator and adjusted the flow to the generator using the in-line valve (this way the gravity feed is controlled). I hope this can help you out. My 1000 would run for almost 1.5-2 days on that big tank. You can use whatever size you need but i think the control valve (flow) is mandatory to control flow. Last thing you want is a gas covered generator.. Goos luck

 

I know a way to feed this unit without the worry of gravity feed in which would be safer using the amount of fuel you want to store.

I need to get back to the shop tomorrow and verify a couple things before posting, The ole memory isn't what it use to be.


Check back then......

 

OK, thanks...let me know if you need any specifics (model #, etc.) or any pics...as this is a 7,000W generator, under load, this baby burns thru 5 gallons of gas in about 6-8 hours...so I'm lookin' for a gas tank that is at least 18 gallons if not bigger.

Like I said, I just don't want to end up blowing my self up or burnin' the house down.

 

There will be no worry in that.....

 

I know, I just wanted to bump it back up to the top so folks would see the post. Beer 4U2

 

A fuel tank that is placed too high or has higher fuel volume level could place excessive fuel pressure on the float valve (needle). This could result in the carburetor float valve to “pop-off” the seat and flood the carburetor, engine crankcase or possibly flow out the carburetor.

I searched the Honda Carburetor Service Manual and a pop-off pressure value is not given.

I have seen larger tanks installed on equipment with no problems. Then I have seen near disasters.

 

That is why i used a inline valve (cracked open) to control the amount of fuel that is flowing to the carb.

 

I use an outboard motor tank as an aux generator tank. It rests on top of the generator fuel tank and feeds into the carb by gravity.

 

Given all the fed and state road taxes when you initially purchase gasoline plus your need for longer run times have you considered converting to propane or natural gas? I know fill out proper forms and get back the excess taxes for non-road use and it costs to convert but might average out to a better deal since you want longer run time..

 

Yes, THAT is what I am trying to avoid.

 

I thought about that but am not sure the cost of converting a gas powered Honda 4 cycle engine to LP. LP would be my only choice in our area and it would be more convenient, but I figured the expense would probably outweigh any benefit. I'll perform some Google seaches on the conversion but if you have any links, let me know.

 

Actually just found a really good link for converting gas to propane (and even the ability to use both):

Honda Generators Propane and Natural gas Kits.

 

For a few hundred bucks the LP conversion looks promising although if anyone has done this, I'd like to hear from you. Also, any idea just how long would a 40# tank of LP last with a 7000W generator? 80#? I mean, I know LP is a cleaner way to go, but unlike regular gas, it can be tough to tell how much LP you have left. Measuring that stuff is a right pain in the a**.

 

They make gauges. Just look at a forklift. Also I have seen strips that go on the side of the tank that apparently react to temperature differences and show you how much but of course most accurate is to weigh it.

 

OK,

Here's what I Have......

There is a blind threaded boss on the bottom of the head, You can remove the valve cover and place a rag in the bottom of the head to plug the oil return ports so shavings don't enter the crankcase.

Use a 1/4" drill bit and drill the boss the rest of the way through the head.




Now, With Briggs part # 691609 or Kohler # 25 155 02 elbow fitting measure the thread length. Drill the boss the same distance as the threads only then use a 1/8" national pipe thread tap and tap the boss, Screw the elbow into the boss and you now have a impulse port;




You can now install a impulse style fuel pump like Briggs part# 808656 or Kohler #24 393 16-S;





Mount the pump higher than the elbow fitting someplace on the generator frame (example);




Now you can add any tank you want and even go back to the original gravity feed tank by simply hooking it up to the fuel pump.

Fuel pump, Around $35 USD
Elbow fitting, Around $3.00 USD



Good Luck

 

That's the way to go. Nice pics and description 31YTech!

I wanted to add that with this setup, you can use gas from anywhere. You can pull the car up near the generator and run a fuel line from the pump down into the filler neck of the car and use gas from there, or from your lawnmower tank, boat, or whatever has gas in it. Mine is set up this way.

 

Northern has a 10 gal tank, for about $90, that is meant to sit flat, with a fuel guage and a fuel shut off feed built in, included
here's a link NorthStar Gas Tank — 10 Gallon | Generator Gas Tanks | Northern Tool + Equipment

approx 18"W X 24" front to rear, and maybe 7-8" deep or tall

it's the very tank that they use on their 13KW NorthStar generators, which is what i have - pictured here NorthStar Trifuel Generator — 20 HP, 13,000 Surge Watts, 10,500 Rated Watts | 10,000 - 29,999 Watts | Northern Tool + Equipment

Basically i just added a couple of drawer slides (like in your kitchen cabinet drawers) above the generator, next to the gen's original tank (made sure they were rated for the weight of the tank when full) - installed a "T" fitting into the fuel line.

My 13KW gen goes thru 17 - 22 gallons per 24 hours when running, and did it so at night before retiring, i could just go out, shut one tank off and open the other without having to shut down gen, refueling the tank with flashlight in my teeth, etc.

i did put a "tray" under the tank, in case of any leaks, spills, etc, they'd be directed away from the engine, same as the fuel tank northstar installed overtop the gen head

i also used quick detach fittings, so that for svcing the motor, i could easily detach the tank and remove - the quick detach fittings automatically shut or close the fuel line when disconnected

but this way, i'm using gravity to feed fuel, same as the original tank - less complexity and one item less to fail, ie a fuel pump

if you're interested, i can take some shots and post

 

31YTech, wow, thank you so much! Nice pics and step by step including part numbers...looks like I have a nice little project to do one of these weekends.

One quick question, what is the typical size for the gas line tubing using the elbow and pump you have listed?

 

Yes, if you can post pics and part numbers, that would be helpful. Thanks for the links!

I'm also looking at Northern for the fuel tank but am looking at an aluminum 18 gallon version (RDS General-Purpose Fuel Tank — 18-Gallon, Rectangle | Auxiliary Fuel Tanks | Northern Tool + Equipment). I have a solid platform that I can place it that would sit about 4 feet away and above the generator so it would be safe.

My generator has a fuel shutoff for the built-in 5 gallon fuel tank so my plan would be the perform the changes that 31YTech supplied and simply use the larger fuel tank. If the larger tank doesn't have a shutoff built in, place one in line between the large tank and the generator. Then, when the larger tank starts running empty, shut that one down and kick on the 5 gallon "reserve", re-fuel the 18 gallon and switch back.

 

if it's sitting higher than the other tank, then gravity will fill the orig gen's tank- a simple "T" fitting in the fuel line with a shut off on both tanks. But a warning - be sure to use one tank at a time - my second tank is a little higher than the orig tank and i forgot the shut off open on the orig tank when i opened the 2nd tank - came out later to find fuel dripping all over, it had back filled the first tank and was flowing out the filler cap

btw, weight of gas is 6.15 lbs per gallon

 

Yes, thanks, the last thing I need is a nice gas pool.

What size diameter fuel line are you using?

 

Might be a stupid question but where the heck is the fuel going in this setup? I'd have thought one would be directly sending the fuel to the carb? What am I missing???

Also, with the elbow and threads, should you put some sort or tape or putty on the threads prior to threading it into the boss?

 

The size fuel hose needed is 1/4" and yes put tape or some type sealer on the elbow threads.

Here is the fuel line hook-up.....




The idea behind the fuel pump install is to do away with 18 gallons of gas being gravity fed, As Airman posted that much weight might pop the float valve off the seat and flood all over.

With the top of the 18 gal. tank mounted level with or lower than the fuel pump there is NO chance of flooding, The fuel pump will only operate when the generator is running. A in-line cut-off valve between the tank and fuel pump is not a bad idea if you "T" into the fuel input line with the original tank as a back-up.


Have Fun !

 

Got it! Yup, this is bring me back to my shop days in Junior High pulling apart my Dad's lawn mower. It was never the same after I got done with it.

Thanks again for all your help...ordering the parts now!

 

One last question...are there such things as quick connect/disconnect couplings for the fuel line? As my generator is portable, I will be wheeling it out to attach to the auxiliary gas tank when in use and disconnecting from the auxiliary gas tank and wheeling it back in the basement when not in use.

 

here you go - if the link doesn't work, then use the second link and punch in "fuel line quick disconnects" in the search box
those are the ones i have, have had them on my gen since 2000, and work great, no leaks, and when disconnected both sides (male and female) shut tight
Wicks Aircraft Supply

Wicks Aircraft Supply

you might want to call in as what they're showing there are the female side of the body, i didn't see the male side - and when i got mine there were about $11-12 for a set, male and female

and what Y31Tech said, 1/4" should be fine - i believe mine are 3/16" as that was the fuel nipple on the honda gen (20hp)

31YTech - curious - have you ever tested how much head that pump will pull or how far - the how far part is more interesting cause what cheese said about being able to pull from the gas tank in our cars, would be nice

 

Perfect, that is just what I am looking for! And the first link works great. I will call about getting a set. Thanks again!

 

here are a couple shots of the aux 10 gal and the quick disconnect fitting




and figured some with generators might find this idea useful
that 20HP honda is loud, and i mean deafening loud
i built a shed for it, insulated well with sound matting and 3/4" plywood, built an air channel enclosure that feeds air to the engine without letting sound escape - all that helped but you could still hear the damn thing inside the house

it wasn't till i put a "sanitary clamp", basically a quick release clamp, a pc of SS flex exhaust line and ran it into a muffler. The flex pipe is literally just slid into the muffler - a really loose fit of 2" flex into 3" opening and all that exhaust sound is now history - the mechanical noise of the engine itself is all that you hear and it's directed away from the house by that shed

in the first shot, you can see the quick detach clamp hanging open, on the muffler, and the flex pipe wrapped in asbestos tape stored by the fire extinquisher

 

Wow, now THAT is a rig!

Where we live (in the woods), when the power goes out, there are so many generators that fire up we affectionately call the wooded hill we live on "generator hill". I haven't worried too much about how loud my generator is, and you are right, it is loud.

That's a cool lookin' setup though. I built a ramp for mine so I could wheel it in and out the basement door.

 

i run a business out of my home and need the lights, phones, computers (and in the summertime, the A/C)
it gets humid around here and for some reason, i'm near a substation that all you have to do is say the word "thunderstorm" and power goes out
in ten years that gen has run 577 hours and been abused - i forgot we upgraded our A/C from a 4 ton to a 5 ton and left too many appliances on when power went out - but that unit carried a 5 ton A/c, refrigerator, a computer drawing 1.9 amps (printer turned off) lights and phones.

in the winter months i use a makita 5800W - everything here is natural gas (heat, hot water, dryer & stove) and that carries me fine - i did a similiar sanitary clamp flange on the muffler on the makita so the same flex hose & muffler are used for it

 

Larry,

You brought up a good point, black 1/4" hose is best to run from the tank to the pump but 3/16" would be needed from the pump to the carb.... I've found "Tygon" (clear 2 cycle hose) to be the best/easiest to use when going from 1/4" barb to the 3/16" Honda carb inlet.

You can slide the end of the "Tygon" on the end of your needle nose pliers then spread the handles apart a few times. This will stretch the "Tygon" so it can be slid on the 1/4" fuel pump barb.



Honestly, I never had a reason to check into this. But..... Since it's been brought up, I just may be able to find the time to do some testing in the next couple days.

Got a bunch of brand new Dixie Choppers laying around with the same fuel pump and a 25' roll of 1/4" fuel line along with 8 shop fuel cans full.

The only snag might be the carb may run out of fuel before the longer hose fills with fuel (air pocket in empty hose). If that's the only set-back a marine fuel tank primer bulb could be installed in-line near the vehicle end of the hose.

A little playin/testin will tell all......


BTW, I dig the little chrome muffler.....

 

only issue with propane for me (my gen is a trifuel)
a) propane reduces power of engine by 10% (nat gas by 20%) so that reduces kilowatts your engine will be able to produce - in my case, we only use that gen in summer to carry the center A/C and we've already stretched that eng & gen just beyond it's limit

b) for the larger engines, like my 20HP, a 40lb tank will not feed it properly, something about "vaporization rate" and i would have needn't some sort of diaphram that would help the propane vaporize faster - suspect a 40lb would be marginal on yours at 13hp (assuming your's is 13 hp if 7000W) on cold days

advantages to propane are beautiful - long long term storage with no degradation of the fuel, but for me it just wasn't worth the hassle

and if it helps, 40lb tank is approximately the energy value of 20 -22 gallons of gas - when i studied it, i calculated i would need almost a 40lb tank per day

 

I have a question with regards to the boss below:



The boss is located below the valve cover and therefore, should I worry about oil getting into the line?

 

No,

The return holes in the bottom of the head are large enough oil will not puddle into the hole. Now, A little oil splash may enter the hole. For this reason is why I said "Mount the pump higher than the elbow fitting", You don't want a downward sag in the hose going up to the pump either go straight out of the elbow up to the pump. This will eliminate the hose/pump from filling with any splashed oil.

 

OK, thanks. I will make sure there is no opportunity for oil to pool in the line.

 

Just an FYI with regards to Wicks and the fuel line disconnects, here are the actual part numbers should anyone wish to order these for a 1/4" fuel line:

QUICK DISC INSERT 1/4 Part Number: 220-04 (QUICK DISCONNECT INSERTS) (220-04) (Note: This is the male)

QUICK DISC BODY-INLINE 1/4 Part Number: 170-04 (QUICK DISCONNECTS) (170-04) (Note: This is the female)

 

OK, so I ordered and received the following fuel tank:

RDS General-Purpose Fuel Tank — 18-Gallon, Rectangle | Auxiliary Fuel Tanks | Northern Tool + Equipment

My question is this: It has a 3/8" NPT pickup and 3/8" NPT return fitting...being a little new to all of this, I can understand the pickup but how do I connect up the return? Do I need to? Thanks!