Okay, I want to throw my petcock into a busy highway

[castlekin]

I have a crazy fuel problem, if I look I get no fuel into the fuel filter in no position what so ever unless I get the bike running. Then it pulls fuel into the carb but only a little bit. Strange, huh?

Well if anyone wants to chat about it, pm me for my skype address. I have a hard time describing what is wrong in text sometimes.

[cowboyup3371]

Is this an external fuel filter or are you talking about the one built into the petcock? If you added one then get rid of it. They won't allow enough fuel to flow correctly with these kinds of setups.

[castlekin]

rode the damn bike 20 miles today, fine, then it does this. Its an external filter, in the line. possibly don't need it due to the filter screen on the petcock. It is a GS850GL.

[Mekanix]

Isn't the filter screen in the tank just as fine as the one you've added?

twice the filtration media might be overdoing it.


this is what I would wonder in this case

how does it work on prime with the filter draining into a gas container

If you disconnect the fuel filter and redirect it into a gas container does it flow better?

doubt it, but could it be Vapor lock ?

In the past I've tried a filter and then removed it.
Instead I installed a T adapter and a hose going down below the carbs with the end caped.
It lets the larger particles fall down the line.


good luck,

[castlekin]

Well, I must say I don't know much about this bike yet, but when I bought it, it had the extra filter on it. So, I thought it belonged. I get fuel flow all the way to the "second Filter", then after that I only get fuel going to the carbs only if the bike is running. it seems to "lock" at the "second filter". I will remove it and replace the whole fuel line. Also, the above fuel flow happens in all positions of the petcock. If I take the line off, only then do I see a difference of fuel flow in the different positions.

[landshark]

I know people say not to use a second filter, and sorry to confuse the situation, but i have been using an inline filter with no problem at all.


So far!

[tkent02]

Fuel is supposed to stop flowing when the engine isn't running, the petcock shuts it off.

[Tom R]

The petcock has a diaphragm in it that opens engine vacuum and closes with none. Sometimes they go bad. You'll see the vacuum hose that runs from the petcock to the engine side of the #2 carburetor. Pull that off the carb and use your lungs for vacuum. If you end up with gas in your mouth - you need to rebuild the petcock.

[DanTheMan]

The only time you'll have fuel flow without the engine running and the petcock in run or reserv is if your petcock is bad. Prime position will allow it flow without the engine running. Get rid of the external filter, it'll starve your carbs.

[Dave8338]

Remove the second filter. People don't usually throw a second AIR filter into anything and that, to some extent, would make more sence.

[mike_of_bbg]

Sorry, is there a problem with the engine running? Or are you just confused by the petcock?

I'm a bit more ambivalent about the use of a second filter than some. If it's a filter designed for a gravity-fed system, it's not likely to stop up your flow unless it's really old and dirty. Filters designed for gravity systems usually don't filter all that well though. They'll trap air which can lead to vapor lock, but also allow you to see fuel flow. They might stop some chunks from gunking up your needles. Pros and cons.

The fuel flows down to your carbs where the floats and needles will shut off the incoming flow at the proper bowl height. If you're sitting there with the bike idling, those carbs won't allow too much more fuel in. The only time I could easily see fuel flow in my old filter (I don't have one any more) was if the bowls were empty and I put the petcock on prime - and then only for a few seconds until the bowls were full.

[bwringer]

Overall, it would probably be best to toss that old petcock in the trash (a busy highway would be impolite at best) and get a new one from your favorite source for Suzuki parts. Petcocks only last about 25 years or so, and the rebuild kits are often a waste of money and time.

But yeah, it's a vacuum-operated petcock -- it's only supposed to flow when the engine is running.

And petcocks include fine-mesh filter screens (at least, they're supposed to), so external fuel filters are superfluous.


A petcock is a critical valve that controls the flow of an extremely flammable substance six inches from your crotch. I don't think it's worth farting around with homemade fixes.

[castlekin]

Ok, either I am not writing it right or everyone is just skimming the info, yes I know that in the PRI position fuel should freely flow, however it is not. It is allowing fuel to flow only when the engine is running. Same in all other positions. And again, this is only while hooked up to the carbs, if disconnected from the carbs, flow is just fine.

Three hours before that it was working just fine for a 25 mile ride to town and back.

If I suck on the vacuum line for the diaphragm on the back of the petcock, you can hear it opening and closing, but no fuel " to the carbs" when connected to the carbs. When I get the bike running only then is it sucking fuel into the carbs, and again, this is only happening in ALL positions of the petcock.

So, explain why it was fine not but a few hours ago and then decides that it is finally done now.

I hope that explains it better.

And yes there is a bit of a problem while the engine, after a few minutes, the engine starves itself.

[cowboyup3371]

Castlekin, you've been given the advice as to why it MIGHT be happening. Take and TRY OUT the advice you are given that you asked for and then rule it out. Don't rule it out before making sure.

External filters can work but don't very often and are not needed when your petcock already has one.

If PRIME is not working than you have a faulty petcock. It doesn't matter if it was just working - it isn't now. You won't get a vacuum to the carbs unless the bike is running so you'll need to use the PRIME to get fuel in there first and then go from there.

So essentially, lose the external filter, make sure your petcock is working, and if not replace it. It's that simple.

[tkent02]

Some of the petcocks 1980 and newer need engine vacuum to start the fuel flowing even on PRI. I am not sure if yours is like this, sounds like it may be, and it's working correctly. Lose the filter, see how it works.