GStwin.com GS500 Message Forum

Main Area => General GS500 Discussion => Topic started by: indestructibleman on September 23, 2005, 03:31:08 PM

Title: fuel delivery problem?
Post by: indestructibleman on September 23, 2005, 03:31:08 PM
yesterday, i checked my valves.  don't have the shim tool or a micrometer, so all i could do was say, "yup," those need to be adjusted.

took me way too long to get everything back together (had everything on then noticed the head cover gasket wasn't seated properly, etc . . .).

i had also disconnected the choke and throttle cables from the carbs (misread some directions, thought i had to take the carbs off).

anyway, yesterday i got everything running and the throttle cable and idle screw adjusted ok with the tank off the bike.

then i put everything back together.

today i start the bike, with choke on like always.  it starts, but the idle stays low.  i mess with the choke and see that it'll die if i take the choke off.  so i start fiddling with the idle screw and it dies.  then it won't start.

so, i take the plastics off and loosen the tank to make sure i turned the valve on.  it's on.  then i try the starter and it starts, but dies pretty quickly.

so i decided to take the tank off and look at stuff.  when taking the hoses off the shut off valve (after shuttin it off of course) a little fuel came out the top of the hoses so it seems fuel was flowing.

anyway, i looked and the choke and throttle cables look to be moving fine.

just for fun, i reconnected the battery and right now i have the engine running fine without the tank on.  :dunno:

any ideas?
Title: fuel delivery problem?
Post by: scratch on September 23, 2005, 04:09:47 PM
Did you drain the floatbowls? Did you set the petcock to PRIme to refill the floatbowls? Did you crack one of the floatbowl drain screws to see if there was fuel flow to the floatbowls? Next stop - the vacuum hose: both ends on? Give a little screwdriver handle tap to the floatbowls or the petcock.
Title: fuel delivery problem?
Post by: indestructibleman on September 23, 2005, 04:47:05 PM
i've got it on prime, and there appears to be fuel in both bowls.

of the two hoses that attach directly to the tank, one is going to what i believe is the charcoal canister?  the other (it hooks on right next to the fuel tank petcock) goes to nowhere.

it seems that if i leave the bike for 10-15 minutes, it'll start after a lot of cranking, then run weakly for half a minute before dying.
Title: fuel delivery problem?
Post by: scratch on September 23, 2005, 05:08:37 PM
That sounds like the canister is clogging and not allowing enough venting of the tank. Disconnect and remove the rollover valve next to the canister and use some carb cleaner to loosen up the valve. If that doesn't help then just disconnect the hose from the top of the rollover valve, and see if that helps. This is one of the reasons you can't overfill a CA bike, because the gas will flow down to the charcoal canister and when it mixes with the charcoal it becomes mud and no longer porous.

Edit: shake the rollover valve first to hear if it rattles the slide back and forth freely, if it does than you don't need to use carb cleaner.
Title: fuel delivery problem?
Post by: Affschnozel on September 23, 2005, 05:30:01 PM
After you bought the  bike, can't you just rip this charcoal canister out, or do they check the emissions of the bike when you have to pass the technical test in CA?
Title: fuel delivery problem?
Post by: scratch on September 24, 2005, 09:27:41 AM
Luckily you could rip it out as they don't require smog testing of m/c's, like they do cars every other year. But, you're speaking of the technical test and the DMV will require it be there for you to obtain a registration. Until I have problems with mine, I'm not disconnecting.
Title: fuel delivery problem?
Post by: indestructibleman on September 24, 2005, 10:42:46 AM
the rollover valve rattles, both carbs produce fuel if i open the drain screws, both spark plugs give me spark, and i can't get the engine to fire at all.

if the canister were the problem, would i be able to run with that hose disconnected?
Title: fuel delivery problem?
Post by: indestructibleman on September 24, 2005, 02:34:30 PM
upon looking at it again, i think the spark i'm getting may be a bit little and yellow.

one plug gives me completely yellow spark and the other gives me mostly yellow (say 80%) with just a bit of blue in there.

it's been a couple of years since i've checked spark on an engine.  anybody have photo ref for strong or weak spark?

also, i definitely have spark.  would the spark being weak (but present) be enough to make the engine not fire at all?
Title: fuel delivery problem?
Post by: scratch on September 24, 2005, 09:57:35 PM
Yes, you would be able to run with that hose disconnected; that's what I did with my SRX, I just left the hose dangling.

No, it should still run, since it runs with the tank off.

I'm at a loss. I'm thinking, open the gascap on the tank, or screw the idle screw in more.

The sparkplugs are getting wet, right? Well, I mean, if they're staying wet then they're not sparking (strong enough). Get the bike running without the tank on and then check the plugs. Make sure you have enough gas in the floatbowls and the lines (put on Prime).

What were the measurements of the valve clearances? You may actually have to do a valve adjustment, to get your compression back, if they're too tight. Maybe do the 'thumb over the sparkplug hole' compression test.

Edit: Are both the choke and throttle cables routed the way you had them before? Could the tank be mashing one of them (probably the choke) and not allowing it to operate properly? And, the tank isn't pinching the fuel line? Or, the hose to the canister? Or, the crankcase vent tube?
Title: fuel delivery problem?
Post by: indestructibleman on September 25, 2005, 01:51:43 PM
i put a hell of a lot of carb cleaner in the carbs, and it started up (for the first time in two days).

from this i'm thinking the problem was fuel after all.  also, yesterday, at my father's suggestion, i opened the drain screws on the carbs and actually emptied the fuel from them.  then i reconnected the tank and put the petcock on prime, and they did not fill up again.

i know i have fuel coming out of the tank valve.  so now i'm going to go on down the line and see if there's any blockage between tank/petcock/carbs.

thanks,
will
Title: fuel delivery problem?
Post by: indestructibleman on September 25, 2005, 01:59:30 PM
i disconnected the hose from the petcock to the carbs at the carb end and left it hanging.

i then reconnected the tank, opened the tank shut off valve, and put the petcock on prime.  no fuel came out.  am i right that with the petcock on prime, fuel should just be running out?
Title: fuel delivery problem?
Post by: mjm on September 25, 2005, 02:56:42 PM
Quote from: indestructiblemani disconnected the hose from the petcock to the carbs at the carb end and left it hanging.

i then reconnected the tank, opened the tank shut off valve, and put the petcock on prime.  no fuel came out.  am i right that with the petcock on prime, fuel should just be running out?

On prime fuel should fall aout as fast as gravity can make it flow.  Now, one of five things is going on.

1- The tank valve is not really "on" - On is when the slot in the tank valve is in line with the tube from the tank -turn it too far and you turn it  off.

2. You have pinched BOTH hoses from the tank to the petcock.  If fuel was flowing in either hose and the "prime" position is working on the frame mounted petcock, then fuel will flow.  So, they would both have to be blocked for fuel to not flow.

3.  You hooked up the vacum hose to the fuel input on the carbs (and the fuel to the vacum input.)

4.  The frame mounted petcock it completely blocked by crud.

5.  The tank is empty or the screen in the bottom of the tank is completely blocked by crud.
Title: fuel delivery problem?
Post by: indestructibleman on September 25, 2005, 02:58:29 PM
i think something had clogged the tank valve.

right after i wrote my last message i double checked and found that there wasn't anything coming from the tank.  opened and closed it a couple of times and then fuel started running.

now everything seems to be fine.  i won't have to take the bus to work this week after all. :cheers:

thanks for the assist, Scratch. :cheers:
Title: fuel delivery problem?
Post by: scratch on September 26, 2005, 12:18:03 PM
Thank mjm, too!

I'm glad it worked out!
Title: fuel delivery problem?
Post by: indestructibleman on September 26, 2005, 12:29:07 PM
thanks, mjm.  almost didn't see your post there.