[NoobMaster]

Hi guys, after trying to attempt to tackle this problem on my own I can't seem to get an idea where to start. The bike is a 79 gs850. My bike used to idle well before I encountered an electrical problem(If you read my last problem you'll know). This electrical problem required me to take the gas tank off, which meant disconnecting the fuel and vacuum lines. I eventually solved the electrical issue and decide to test the bike at that moment without the gas tank on. And the bike ran but I turned it off after a couple of seconds. Okay, so I decided to put the gas tank back on and start up the bike. The bike starts up, idled high for a moment, idled lower, then sputters out and died. This whole period lasted about 30 seconds. Now the bike will only run for about two seconds off some starter fluid and sputters if you try touching the throttle. When I first got this bike and forgot to attach the vacuum line to the petcock( because I didn't know vacuum lines existed) it did this exact same thing, including the sputtering. It sounds almost like it's not getting fuel. Could this possibly be poor fuel or vacuum lines? I feel like it's something simple.
-Thanks everyone

 

[CRracer712]

Is the petcock mounted directly to the tank? Did you try on and reserve?

Might be as simple as pulling petcock to see the the screen is plugged.

 

[NoobMaster]

Is the petcock mounted directly to the tank? Did you try on and reserve?

Might be as simple as pulling petcock to see the the screen is plugged.

Petcock is mounted directly to the tank, both on and reserve didn't help. The PRI setting seemed to be functioning. Is it safe to say it's a fuel problem? See before I took the fuel tank off the bike, it ran fine. What im guessing is a possibility is that on my first attempt at starting the bike after reattaching the gas tank is that it ran for 30 seconds due to leftover fuel from when it was the last functioning properly. I'm a little suspicious if the vacuum hose is functioning properly or not. But dang do I feel stuck.

 

[NoobMaster]

Also seemed to be backfiring before it died, don't normally hear these sounds. Could a weak battery cause this?

 

[Stablefull]

Hmmmmmm...a shot in the dark but you took the tank off and put it back on. Could be some dirt and gunk got moving around in the tank and went straight to your fuel filter or carb. Has the bike been sitting for a spell? I would open the float bowls and take a look. Also, if you don't already have one, I would put in an inline filter.

 

[NoobMaster]

Hmmmmmm...a shot in the dark but you took the tank off and put it back on. Could be some dirt and gunk got moving around in the tank and went straight to your fuel filter or carb. Has the bike been sitting for a spell? I would open the float bowls and take a look. Also, if you don't already have one, I would put in an inline filter.

The bike has been sitting for a spell however when I first attempted at getting it running (before taking the gas tank off) it would run fine. And it would start up first try Everytime I tried. The battery seems to be really weak as it’s turning over but you can hear it dying. Could this contribute to it not starting? Gonna put it on the charger now and see what happens.

 

[CRracer712]

That's why I'd pull the petcy and drain fuel to see if there's debris. Most petcocks have a screen, but it could be torn or deteriorating.

If debris comes out of tank, move on to what steve says.

Backfire in carb is generally rich(sticky float?) Backfire out exhaust generally indicates lean.

Vacuum lines ok?

 

[Critter]

Clogged fuel line or petcock.

 

[NoobMaster]

That's why I'd pull the petcy and drain fuel to see if there's debris. Most petcocks have a screen, but it could be torn or deteriorating.

If debris comes out of tank, move on to what steve says.

Backfire in carb is generally rich(sticky float?) Backfire out exhaust generally indicates lean.

Vacuum lines ok?

I guess those will be my next steps. There is an inline fuel filter that filled up when I set the petcy to PRI. Could this still indicate a clogged fuel line somewhere? The vacuum line appears to be okay, and the backfire was coming from the exhaust.

 

[mike721]

Sounds like your problem is with the vaccum petcock or crud in the screen, it's not getting the fuel to the carbs. Take it apart and check everything, this is going to be a simple fix once you find the problem.

 

[NoobMaster]

Update
Didn't do anything yet(except recharging the battery) but just thought you guys should know I got it to run the first couple of tries but it wouldn't idle on its own. If I gave it a little bit of throttle it seemed to be able to stay on. Still made a sputtering sound when I pulled the throttle. After about a minute of holding the throttle a little to keep it alive, I let it go to see if it would idle and it died. Not starting up anymore. Also found a little exhaust leak where the muffler connects.

Check the link to hear the sound.

 

[NoobMaster]

Just tried taking off the fuel line from the carbs and leaving the vacuum attached to the petcock while trying to start it. A few drops come out of the fuel line does that seem right?

 

[NoobMaster]

Trying to narrow down the problem here, I'm completely stumped. If fuel is coming out of the hose while trying to start it is that still a petcock problem? The vacuum line appears to be working as I feel suction when removed from the petcock...trying to narrow it down here. What could this possibly be?

 

[Stablefull]

Just tried taking off the fuel line from the carbs and leaving the vacuum attached to the petcock while trying to start it. A few drops come out of the fuel line does that seem right?

Yes, there's always a little bit of gas in the lines.

You mentioned that it had been sitting for a while but would still start and run. Consider that the gas in the tank is still aging. I would do the following:

1) Pull the petcock and see if there is debris in the screen and/or if it's getting old and worn, essentially deteriorating. Replace the screen and/or petcock if necessary.

2) Replace the gas with fresh. Add half a can of Seafoam to new gas. Use non-ethanol gas if you can find it.

3) Replace the inline filter if you don't know its age. They are cheap and easy to swap out.

4) Open your float bowl(s) and see if there is any gunk in there. If so, get the gunk out and spray it out with carb cleaner. Note: make sure to close petcock while working with anything downstream from it. Ask me how I know

5) Check air filter and replace if dirty and clogged.

When you get it up and running again, get it warm if you can and see if you can get it to run for 10-15 minutes. This will get the Seafoam throughout the carb and working on breaking down any dirt, debris, or varnish. My experience is that it burns hot and tends to dissolve most dirt and grime. You may want to pull the float bowl(s) once more afterwards if you think a big chunk may have broken loose in the carb. Make sure to do the petcock/screen and inline filter first. I bought my XR650 from my cousin and it rode well for a short time, then wouldn't rev cleanly and sure enough, there was **** in the float bowl. I took the petcock out to find the screen was missing. I asked my cousin and he said his mechanic was supposed to replace it and put in an inline filter and forgot. So gas was going straight from the tank to the carb. This was after light use for about 18 months after he had back surgery. He would start it up once a week and maybe take it for a 5-10 minute ride if his back felt okay. Under those conditions, sediment had settled to the bottom of the tank and was getting sucked into the carb. Running Seafoam in my new gas helped tremendously.

 

[Critter]

Is there fuel past that inline filter?

 

[NoobMaster]

Is there fuel past that inline filter?

yes

 

[NoobMaster]

Also, I meant a few drops would come out of the fuel line when disconnected from the carb, and me clicking the starter button to test it. Just to be clear.

 

[Critter]

should be more of a stream

 

[NoobMaster]

Yes, there's always a little bit of gas in the lines.

You mentioned that it had been sitting for a while but would still start and run. Consider that the gas in the tank is still aging. I would do the following:

1) Pull the petcock and see if there is debris in the screen and/or if it's getting old and worn, essentially deteriorating. Replace the screen and/or petcock if necessary.

2) Replace the gas with fresh. Add half a can of Seafoam to new gas. Use non-ethanol gas if you can find it.

3) Replace the inline filter if you don't know its age. They are cheap and easy to swap out.

4) Open your float bowl(s) and see if there is any gunk in there. If so, get the gunk out and spray it out with carb cleaner. Note: make sure to close petcock while working with anything downstream from it. Ask me how I know

5) Check air filter and replace if dirty and clogged.

When you get it up and running again, get it warm if you can and see if you can get it to run for 10-15 minutes. This will get the Seafoam throughout the carb and working on breaking down any dirt, debris, or varnish. My experience is that it burns hot and tends to dissolve most dirt and grime. You may want to pull the float bowl(s) once more afterwards if you think a big chunk may have broken loose in the carb. Make sure to do the petcock/screen and inline filter first. I bought my XR650 from my cousin and it rode well for a short time, then wouldn't rev cleanly and sure enough, there was **** in the float bowl. I took the petcock out to find the screen was missing. I asked my cousin and he said his mechanic was supposed to replace it and put in an inline filter and forgot. So gas was going straight from the tank to the carb. This was after light use for about 18 months after he had back surgery. He would start it up once a week and maybe take it for a 5-10 minute ride if his back felt okay. Under those conditions, sediment had settled to the bottom of the tank and was getting sucked into the carb. Running Seafoam in my new gas helped tremendously.

How do you know 🤣 ?

Quite interesting, guess I'm gonna have to give it a shot. Wondering if I'm gonna have to order more parts or can use something I have to clean what I already have. I guess a lot of suspicions is from the petcock and crud, gonna check that out and give it another go. Do you guys think this is more likely to be gunk in the petcock and gas tank or gunk in the carbs? This issue really has me wondering.

 

[Stablefull]

Also, I meant a few drops would come out of the fuel line when disconnected from the carb, and me clicking the starter button to test it. Just to be clear.

Sorry, I misunderstood. Like Critter said, there should be consistent flow.