GS450L - engine stalls after start

[Guest]

We did a test start on my bike this morning and it starts. It runs briefly and then the idle starts dropping and it stalls.

What we've done to date to get the bike road ready after an extended time sitting:

• cleaned the carbs
• reinstalled the carbs
• checked spark plugs (look good - no corrosion, no black oily stuff, etc)
• replaced the fuel lines and vacuum line off the carbs

To balance the carbs, obviously the bike needs to be able to run for longer than 20-30 seconds at a shot. My friend is going to be coming over later this week to help me work on it and I'd like to be able to research some possible reasons before he gets here.

Thanks!

[pete]

Do you know your fuel tap/petcock is operating correctly? Are you sure you have the hoses on the correct places?

It sounds to me like it's running on whatever fuel is in the float bowls.

Between starts, do you have to open the prime screw or set the tap to prime before it will run again?

To test the tap, put it in the "On" position, pull the fuel and vacuum hoses off. Suck on the vacuum hose and it should start running fuel out the fuel hose.

Also, have you set the idle? Turn the idle screw in some more and see if it keeps running.

After the carb clean, did you set the mixture screws to about 2 turns out?

And of course how did you do the carb clean? A full dismantle/dip or just some spray?

[Tamara]

Do you know your fuel tap/petcock is operating correctly? Are you sure you have the hoses on the correct places?

I marked the petcock so I'd remember which was which so I got that right.

It sounds to me like it's running on whatever fuel is in the float bowls.

Between starts, do you have to open the prime screw or set the tap to prime before it will run again?

i did put it on prime once for one of me three start attempts.

To test the tap, put it in the "On" position, pull the fuel and vacuum hoses off. Suck on the vacuum hose and it should start running fuel out the fuel hose.

My friend did this and gas flowed pretty freely through the fuel line when we were working on it Saturday.

Also, have you set the idle? Turn the idle screw in some more and see if it keeps running.

I tried that today when I started it and it still stalled.

After the carb clean, did you set the mixture screws to about 2 turns out?

I'd have to ask my friend whether he did anything with the mixture screws.

And of course how did you do the carb clean? A full dismantle/dip or just some spray?

He did a full dismantle and cleaned all the bits.

[pete]

Hmmmm... sounds like he did all the right things but obviously something's not quite right...

After it stalls, pull one of the float bowl drain plugs and see if fuel comes out.

If so, then there's something in the pilot circuit restricting the flow or something else unrelated to the carbs potentially.

If there's no fuel in the float bowls, there's the issue, just need to work out why it's not getting fuel.

Are you sure the vacuum hose is not pinched between the tank and frame or anything?

[Tamara]

Hmmmm... sounds like he did all the right things but obviously something's not quite right...

After it stalls, pull one of the float bowl drain plugs and see if fuel comes out.

If so, then there's something in the pilot circuit restricting the flow or something else unrelated to the carbs potentially.

If there's no fuel in the float bowls, there's the issue, just need to work out why it's not getting fuel.

I just tried starting it and no gas was in the right float bowl. The left had a nice little stream come out.

Are you sure the vacuum hose is not pinched between the tank and frame or anything?

From what I can see and feel, it doesn't seem to be pinched but I'll have to lift the tank later today when I have more time to get a look see underneath.

[Tamara]

Update:

The vacuum line had come off. Plugged that back in and gas is now going to both float bowls. I can start the bike but it dies after a few seconds.

[pete]

So after it stalled again there's fuel in both float bowls?

Hmmmm... that says to me either the pilot circuit is blocked (which it shouldn't be due to cleaning) or there's something else non carb related potentially.

Oh, that was one other thing to try... set the fuel tap/petcock to prime and see if that makes a difference.

[wera90ex]

Stalls with choke on? Fresh fuel? What's the inside of the tank look like? Lookin' for rust. What's the spark plugs look like? Will it rev up?
I'm full of questions.

[Tamara]

So after it stalled again there's fuel in both float bowls?

Hmmmm... that says to me either the pilot circuit is blocked (which it shouldn't be due to cleaning) or there's something else non carb related potentially.

Oh, that was one other thing to try... set the fuel tap/petcock to prime and see if that makes a difference.

No difference on prime. We're going to pull the carbs this weekend and recheck the pilot circuit. My mechanical skills aren't up to tackling that by myself so I'll have to wait for my friend.

[Tamara]

Stalls with choke on?

Yes

Fresh fuel?

Brand new fresh gas purchased on Sunday.

What's the inside of the tank look like? Lookin' for rust.

Squeaky clean. The first thing I did was pull the tank, dump the old gas and derust the interior.

What's the spark plugs look like?

I will have to get a new spark plug wrench to pull them. Mine seems to have gone traveling.

Will it rev up?
I'm full of questions.

It stalls the second I touch the throttle.

[pete]

It stalls the second I touch the throttle.

I've seen this before but I can't for the life of me think where and what caused it... I'm actually thinking intake issues when I see this comment... have you oiled the air filter? If so, is it lightly oiled or oiled too much? If you squeeze it, you shouldn't have oil running out, it should just be damp.

If you don't touch the throttle and let it idle on choke, it still stalls or will it idle enough to warm up a bit?

[Tamara]

I've seen this before but I can't for the life of me think where and what caused it... I'm actually thinking intake issues when I see this comment... have you oiled the air filter? If so, is it lightly oiled or oiled too much? If you squeeze it, you shouldn't have oil running out, it should just be damp.

I'll double check the air filter today.

If you don't touch the throttle and let it idle on choke, it still stalls or will it idle enough to warm up a bit?

It never actually runs long enough to warm up.

[Tamara]

I've seen this before but I can't for the life of me think where and what caused it... I'm actually thinking intake issues when I see this comment... have you oiled the air filter? If so, is it lightly oiled or oiled too much? If you squeeze it, you shouldn't have oil running out, it should just be damp.

The air filter is slightly damp. I took it out and tried wringing it out and no excess came out.

I've also checked the plugs and they look good - no carbonized bits, no fouling, etc.

[tom203]

This is odd.... I think that I would pull off air filter, jack up idle stop screw and get the thing to start and at least stay idling (with no throttle input)

[wera90ex]

I was with Pete for a while that I couldn't quite remember what it was. I knew it was something that made me feel dumb.
How about making sure that there are rubber plugs directly under the pilot jets. If those aren't in there forget it. # 28

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