Belly Tank Pump

[JimF2424]

Can you go to slow using a fuel pump?  Will it keep pumping to much fuel to the carbs?   Went for a short ride two days ago and the bike started running sloppy, hesitant, made it home, was going slow when it started.  Went for a ride again and it seems ok.   Was thinking there could be dirt in the belly tank filter, will check the filters this weekend.   Have the belly tank for maybe six weeks, works great until the short ride.  Been raining a lot here in Gulfport MS, and bike stays in one of those Tent shelters that folds up.  Was thinking maybe moisture.   Any advice would be appreciated.

[WintrSol]

Only if one or more of your float valves is leaking. The fuel pump is very low pressure, so shouldn't be able to force fuel past a working float valve.

Another consideration though: look where the pump is mounted. It is very close to the exhaust, and with low airflow, will get hot. I had mine do this in the middle of nowhere on a twisty mountain road in West Virginia. It got hot enough to blow the fuse. I had to pull off that narrow road, let it cool some, and replace the fuse, while big trucks whizzed by. When I got home, I covered the pump with a bit of the foam used to insulate hot water pipes, and secured it with the shiny aluminum tape meant for sealing ducts. No problems since. I suppose anything to deflect the heat will help, that's just what I had on hand.

[SCain]

I thought the fuel pump on a belly tank was to pump fuel from the lower (belly tank) to the top fuel tank, not to pump fuel to the carbs. Don't the carbs still require just a gravity feed from the stock fuel tank?
Just curious.

[Foozle]

Your symptoms sound like bad petrol to me - or maybe a partially clogged vent line.  If you've gotten lots of rain, check to make sure the "T" is attached midway.  Otherwise, you may be getting some moisture in the line.

Q:  Wouldn't a clogged fuel filter cause more issues at high speed (i.e., high flow)?

Also, the cases I've heard of excessive heat on the fuel pump result in a fairly abrupt event.  However, I guess it's possible heat could gradually diminish the ability (volume) of the pump.

Several folks have replumbed their belly tanks to utilize the factory gravity feed system (as Steve suggests), but the "normal" routing pumps fuel directly from the bottom tank to the carbs.  As a result, a functional belly tank is thought to be a deterrent to the dreaded vapor lock.

Personally, I'd check the easy stuff first:  Drain your tank and fill up with fresh gas.

Terry

[WintrSol]

Personally, I'd check the easy stuff first:  Drain your tank and fill up with fresh gas.

Terry

It's not easy draining the belly tank, at least, not mine. There is no bottom drain, so you have to run the pump with the output fuel line diverted into a catch can. I guess because of how the pump works, fuel doesn't drain out when you disconnect the output. Mine is powered even when the run/stop switch is set to stop, so connect the output drain, then turn the key on with the ignition disabled. And wait - it's not what I'd call high-flow. You should know right away if there is water in the tank bottom, so may not need to run it all out.

[The emperor has no clothes]

I thought the fuel pump on a belly tank was to pump fuel from the lower (belly tank) to the top fuel tank, not to pump fuel to the carbs. Don't the carbs still require just a gravity feed from the stock fuel tank?
Just curious.

I know a lot of the SoCal guys have set theirs up this way. But I think the normal operation is for it to run constantly from the belly.

[The emperor has no clothes]

Only if one or more of your float valves is leaking. The fuel pump is very low pressure, so shouldn't be able to force fuel past a working float valve.

Another consideration though: look where the pump is mounted. It is very close to the exhaust, and with low airflow, will get hot. I had mine do this in the middle of nowhere on a twisty mountain road in West Virginia. It got hot enough to blow the fuse. I had to pull off that narrow road, let it cool some, and replace the fuse, while big trucks whizzed by. When I got home, I covered the pump with a bit of the foam used to insulate hot water pipes, and secured it with the shiny aluminum tape meant for sealing ducts. No problems since. I suppose anything to deflect the heat will help, that's just what I had on hand.

I think this is the likely suspect. There have been several reports of this. 

[JimF2424]

Update, drained all the gas and filled with new and went for about a 50 mile ride and running fine.

[Foozle]

Update, drained all the gas and filled with new and went for about a 50 mile ride and running fine.

Please keep us updated, Jim.

I'm trying to amass a knowledge base to trouble shoot my own belly tank, should the need ever arise.

So far, I've had many trouble-free miles (knock on wood!).

Terry

[WintrSol]

Please keep us updated, Jim.

I'm trying to amass a knowledge base to trouble shoot my own belly tank, should the need ever arise.

So far, I've had many trouble-free miles (knock on wood!).

Terry

Just so you know, I found out how to drain mine because, when I rolled it out for the first time, I started smelling fuel as soon as I turned the key. Seems the fuel line to the carbs was starting to crack from age, so I replaced them. Of course, it had been stored with a full tank, so I had to scrounge enough jerry cans to take it all.