Electric Fuel Pumps and Draining Carbs

[Solina Dave]

I've got a '78 GL, so I have a mechanical fuel pump. I may be wrong, but I believe that an electric fuel pump was first designed into the '84 1200GL, and then all of them after that. Also, and correct me if I'm wrong, as I'm not familiar with the operation of the electric fuel pump, but with the key in the "on" position, and the engine not running, would the electric pump still operate, and fillup the carb's float bowls, if they had been previously drained for some reason? Whereas, a mechanical pump would need the engine running, before it could pump the fuel into the float bowls.

Having said that, it would seem to follow, that after a 5 or 6 month winter hibernation for my '78GL, it would take a fair bit of time to fill the bowls enough for the engine to fire and run. As if it's not hard enough to start anyway. I know it doesn't really take too long, based on the time taken to refill the float bowls after going on reserve. But it's delaying the first startup, after winter storage.

This to me raises the question regarding the necessity to drain the float bowls for winter storage. I've heard that if you don't drain them, fuel can evaporate from the float bowl and leave residue that could gum up the workings. Even fuel treated with Sta-Bil would still conceivably evaporate.
All I ever do is fillup to the brim, treat the fuel with Sta-Bil and run it through the system, shut off the engine, and close the petcock. I'm not sure why I close the petcock.
Any comments or suggestions to mull over would be welcome, as I'm on the verge of putting it away for the winter, and I'd like to make it as easy as possible to start it up in the spring.

Thanks............................Cheers...Dave

[DenverWinger]

Turn off the petcock prevents possibility of hydrolock, the fuel can gravity-feed if the tank is full. The fuel pump in line will allow this flow thru the check valves because that's the direction it 'wants' the fuel to go, so really the only thing stopping fuel flow is the floats/needles & seats. If you're sure you won't be running it for a while my choice would be to shut off the petcock, run the engine 'til it runs out of gas and then open the carburetor drains to let what's left out.

In the spring, with your full tank, for the first start turn on the petcock and go refill your coffee. By the time you get back to the bike gravity feed will likely have filled the carburetors, unless there's a bubble somewhere in the system preventing that... Then you'd have to rely on the pump....

[Solina Dave]

Turn off the petcock prevents possibility of hydrolock, the fuel can gravity-feed if the tank is full. The fuel pump in line will allow this flow thru the check valves because that's the direction it 'wants' the fuel to go, so really the only thing stopping fuel flow is the floats/needles & seats. If you're sure you won't be running it for a while my choice would be to shut off the petcock, run the engine 'til it runs out of gas and then open the carburetor drains to let what's left out.

In the spring, with your full tank, for the first start turn on the petcock and go refill your coffee. By the time you get back to the bike gravity feed will likely have filled the carburetors, unless there's a bubble somewhere in the system preventing that... Then you'd have to rely on the pump....

Thanks Denver,
That's very interesting, and seems to make sense. I appreciate your advice.
So, are you saying that since the bike could conceivably be layed up for a considerable length of time, in my case probably November through March or April (5 or 6 months), with the petcock closed, that this would offer more time for fuel to evaporate, and residue to buildup? If that is the case, then it's probably best to drain the carbs. That's good that the float bowls would fill by gravity feed in the spring, after the petcock is opened, but with the engine off. I didn't know that. Another question is; where does the evaporating fuel escape from the carb? Isn't it an airtight system? I understand basically the carb's function. But its construction, not so much.

Thanks again........................Dave

[DenverWinger]

where does the evaporating fuel escape from the carb? Isn't it an airtight system? I understand basically the carb's function. But its construction, not so much.

Not airtight, the carbs are vented, so any gasoline in there can evaporate.
And in the spring, the gravity feed is likely, but not certain, it has to seep thru the fuel filter and both check valves in the pump, so give it time. Loosening the gas cap may "encourage" it a little. Running the starter a little to get some action in the pump might help, too. In fact, if you run the starter enough that the oil pressure light goes out (doesn't take that much) preps you for the second springtime trick and gets some fresh lube on the bearings.

Also, don't forget #3 carburetor fills first since it is the first carb in line from the fuel pump, and has an accelerator pump in it. Working the throttle a few times before cranking will shoot gas into all four carburetor throats if there's any gas in the #3 carb.

If the gravity feed doesn't appear to be working, since the sparkplugs are so easily accessible on an 1100 you can also "Prime" the engine by unscrewing them and squirt an eyedropper of gas into each cylinder and put the plugs back in. Only need to go in finger-tight, you may want to repeat. Remember "priming" a car by pouring gas down the carburetor? Not so easy to do that on the 1100 so we use the sparkplug holes. The engine will start immediately and run a second or two on that fuel. But this works the pump, and your carburetors will be that much closer to having enough fuel to run. Repeat if needed.

Don't forget to re-tighten the sparkplugs after you've got the engine running.

Here in Denver, although it can get blistering cold with subzero lows for a week, you are just as likely to get some nice weeks with highs in the 60's and sometimes 70's at any time in the winter. So I don't do any "winter prep" at all, it's usually nice enough to ride the bikes at least once a month....

....Mark

[Solina Dave]

Thanks Mark, that's a lot of good info. I appreciate that.

Cheers......Dave

[Old Fogey]

Also, don't forget #3 carburetor fills first since it is the first carb in line from the fuel pump, and has an accelerator pump in it. Working the throttle a few times before cranking will shoot gas into all four carburetor throats if there's any gas in the #3 carb.

Only on an 1100, no accelerator pump on his 1000. From someone who rebuilds carbs all the time, drain the float bowls if laying up for months. It will save you (and me) a load of heartache.

[DenverWinger]

My Bad and I know that, too, after owning one for five seasons. Somehow I was thinking "1100" when I wrote that mess! I did recommend draining them, though...

[BaronBigDog]

Given that you scooter will be hibernating it is advisable to drain the carbs, but there will be some residual residue from the gas regardless. I have found, to keep carbs clean as possible I like to run Marvel Mystery Oil mixed with my gas. I actually prefer Versatoil 318, but it is hard to come by. It is an industrial only product as far as I can determine. It removes the varnish associated with gasoline and serves as a upper cylinder lube. It also absorbs water in gas. It is made by Ensign products if you want to try to get it. Marvel is a good second, but not as versatile. It does give good upper cylinder lubrication. I used to get the Versatoil through the company I worked for. It comes in 5 gallon pails so a pail lasts a long time.

As to the electric fuel pump question. I put an electric pump on my 75 GL1000 simply because of limited availability of the original mechanical pump. I found a low pressure pump on eBay that was listed for a Kawasaki and others. I fabricated a bracket from 3/16 angle iron removed the original pump and placed the electric one on the bracket. The overall results are good, but if you are a purist then you will frown on it. Do wire the pump through the kill switch rather than the ignition as the pump will continue to run if you hit the kill switch and leave the ignition on. You still have to turn off the petcock to avoid getting a crankcase full of gas, but that comes with the territory.

The electric pump I used mounts on a single pop in stud for which I drilled the approiate size hole in the fabricated bracket.

You mentioned hard starting issues. Mine starts with just a bump on the starter button. I don't think gas delivery is the issue if it always starts hard. I can offer no solution, but I have never had a hard starting issue now or with the original fuel pump. It has always been bump and start. I have converted to electronic ignition and have hot coils, but even before it started easily.