GS1000 Fuel Flow Problems

[Big T]

Ok. Update here. I did a flow test on my petcock. On RESERVE and on PRIME it flows nearly 1/2 gallon per minute, while on ON it is barely a trickle. I think the petcock is defective. This test was with the fuel cap on and the tank filled to the brim with gas.

Then for kicks I started the bike with the fuel in the carbs and did a flow test from the tank. No flow in reserve or ON and when checking the vacuum line there was a good suction to my finger even at idle.

The fact that it flows on Reserve without the motor running tells you the petcock is bad.

Neither On or Reserve should flow with the engine off, by definition.

I've heard good things about petcocks from Georgefix.com

[rphillips]

Sorry, I maybe didn't comprehend what I was reading. I didn't understand when being checked with vacuum and when checked without vacuum... Should be full flow on PRI only without vacuum, not even a drip from other 2. With vacuum all 3 positions should have full flow.

[zwilmes]

Sorry if I didn't make it clear enough, with vacuum only reserve and prime have full flow and on has a trickle, without vacuum only prime has flow. I'm puzzled as to why ON doesn't work, I took the petcock apart and the diaphragm looks fine and the filter screen on the pickup tube looks fine, took it for a ride today and seemed to work on reserve but was getting some hiccups at cruising speed so I switched it to prime and seemed to smooth out. I tried to put my old petcock back in the but the seal around the switch is leaking and I don't have a replacement for it so I guess for now I'll just run this one on Prime and shut it off when I get done.

[Big T]

There are 2 tubes that feed the petcock, one for On/Prime and one for Reserve.
Unclog the On tube, which is the longer one
The seal for the petcock handle should still be available from Suzuki, as is the disc

[rphillips]

Let's see..."ON" is the only position not working properly, also "ON" is only position that feeds from the taller inlet on the petcock, up in the tank. Both "PRI" & "RES" feed from the lower inlet... Just say'in..

[Mary Hinge]

Sorry if I didn't make it clear enough, with vacuum only reserve and prime have full flow and on has a trickle, without vacuum only prime has flow. I'm puzzled as to why ON doesn't work, I took the petcock apart and the diaphragm looks fine and the filter screen on the pickup tube looks fine, took it for a ride today and seemed to work on reserve but was getting some hiccups at cruising speed so I switched it to prime and seemed to smooth out. I tried to put my old petcock back in the but the seal around the switch is leaking and I don't have a replacement for it so I guess for now I'll just run this one on Prime and shut it off when I get done.

If the fuel level was low then that's exactly what you'd expect the fuel tap to do when the bikes running. If the tank isn't low then everything points to either the diaphragm being Donald or the fuel tap (On" tube/passage being blocked.

[Mary Hinge]

Also, it is NOT recommended to use a fuel filter in line. But if you do, you can get one for a garden tractor maybe at Bomgaars or Tractor supply.

Ain't nothing wrong with running an inline filter, in fact it can only be a plus, just as long as it's not a small 50 cent Chinese one and you change them regularly. Only my view of course after doing exactly that for 50+ years

[zwilmes]

Thanks for the input. As I said before the fuel tank was full to the brim when doing the test so it's not that the fuel level was just too low, and when taking the petcock apart I couldn't see any blockage of any sort. Guess I could try blowing some compressed air through the passages.