Starts, runs, then won't start

[joeninpo]

New petcock on order. Hopefully that works and I can get to my charging system problem...I sure would like to ride this thing instead of push it around the block!

Thanks for all the help!
Eddie

 

[joeninpo]

Funny story to add into the "don't ever do this" section. I'm a long time auto mechanic...mostly on old British cars, but I've never done anything with a bike before. Sooooo, I pulled the gas tank, flipped it over and laid it onto my tool pouch for some stability. I didn't even consider that fuel would leak from the gas cap. Yeah, I got a tool bag with a great gas smell now :-\\\

 

[KEITH KRAUSE]

Sorry I haven't been on here for a few days. I've been busy with work and other junk So, yeah. I have absolutely no fuel flowing from my tank. I decided to throw caution to the wind this morning and just pulled the fuel to see if it spewed everywhere or not. I put the petcock into the prime position and back to the on position several times and nothing even dripped out. I even banged on it with a small hammer just to make myself feel better. That didn't work either, but I did feel better for a second. Now then...does anyone know of a good place to get a new petcock? I would really like to put a manual one so that I don't have to worry about getting enough vacuum again. Stupid '80 GS550L petcocks.....grumble grumble grumble. Idiotic design idea.

Just so you know, according to the factory manual the '80 petcock requires engine cranking to initiate fuel flow even if in the prime position. This info is in the 1980 GS1000 factory manual and I would assume your petcock is either identical or still operates on the same principle. I didn't bother to read the petcock info to see why the '80 petcock won't flow when in prime position (as many others do) but it doesn't operate the same. So re-test before you toss a possibly good part, unless you want to change it anyway.

 

[Wayno]

Runs then won't start.

Runs then won't start.

My 82 gs1100e did the same. It turns out I had the tank vent tube in the wrong location. It was pinched between the bottom of the tank and frame. I don't know if you model has the same set up.

Wayno

 

[Colorado85gs550]

I've already exchanged this info via PM but here goes for everyone else. My issue that sounds so much like yours isn't a fuel issue!

I rebuilt my petcock, replaced the petcock, cleaned my tank vent, took the fuel cap off, hooked a fuel supply up to isolate the petcock/tank all together, etc......

I took the carbs off and cleaned them twice and checked my floats too.......

Here I am with mine:

It HAS to be electrical with mine and spark. It will still turn over but isn't firing until it cools off. I'm ready to test for spark but I'm going to replace the plugs first as I start with plenty of spark and it runs well.

Here's some more info on what mine does when it dies:

1) It just dies like I hit the kill switch.
2) I can hear the starter clutch cycle right when it dies.
3) Everything else electrical still works when it dies, ie: horn/headlight/turn signals/etc


I've started my own thread over in the Electrical/Ignition Tech Forum.

joeninpo, I'm sorry for posting so much of my own stuff here I hope that what I've done so far will encourage you to either NOT waste your money on some of the things I wasted mine on OR for you to have some direction on what I did so far with little or no information from some of the others that can only come up with, "replace this" or "replace that"..........

I'll keep you informed back-N-forth via PMs on what I find......

Paul

 

[joeninpo]

Don't apologize man...lol! Sounds like our issues are very simliar for sure, so we'll see who's riding first I know that I have an electrical issue as well since it won't charge correctly. I'm curious to see if my issue is actually electrical as well. I have a new petcock coming just for peace of mind. I know that Keiith gave some good info on the prime position, but I wanted to change it out regardless. I'm going to put on a new regulator/rectifier as soon as duaneage gets some new ones in. When I'm working on this thing, I wish that I would have spent more money on getting a better bike, but when I'm riding it, I absolutely LOVE it. More to follow.......

 

[joeninpo]

Not that they need much of an endorsement from me, but Z1 ships really fast! Part was ordered yesterday and should be here by Friday or so and I didn't do any type of expedited shipping. Nice...

 

[joeninpo]

Yeah! Got the new petcock in today. Hooked it up and it ran for about 20 seconds. Now, it won't restart at all. Everything is hooked up right and there are no kinks anywhere. I pulled the main fuel line to see if anything was happening at all, and there is no fuel flowing through the petcock at this point. I'm assuming that it's not getting enough vacuum to engage the diaphram, but I'm at a loss at this point.

I ran the battery down trying to get it started, so I'm letting it charge back up while I cool down. I'm about ready to burn this thing to the ground and just go buy something not made by Suzuki. Stupid 80's model petcock......

Anyone got any advice? I'm open to anything

 

[Guest]

Does if flow fuel when you suck on the vacuum line?

 

[joeninpo]

Why yes! I just went out to test it. Works well in both the normal position and the prime position. I pulled the line when it was in the prime position and it just spewed everywhere. I switched it to run and sucked on the vacuum tube and it just spewed everywhere. I love the smell of petrol! So yeah...not the smartest thing to do, but quite honestly, if it would have caught on fire and burned to the ground, I would have danced around the ashes. I washed the fuel away, so I'm just waiting for the battery to recharge now and I'll try it again later.

Any other possibilities? I'm thinking that the fuel just needed some time to work its way into the system before it would crank over, but I ran the battery down before I got to that point. The battery wasn't charged that well to begin with, so this gives me a good chance to make sure everything else is clean and tight.

Thanks again!
Eddie

 

[KEITH KRAUSE]

OK. Based on your last 2 posts, fuel wouldn't flow out of the new petcock unless you applied your own vacuum source.
Are you sure the vacuum line is in good condition?
With the vacuum line connected to the carb, can you blow into the petcock end of the vacuum line and tell that all is clear?
Can you show us a closer up pic of your carbs and all hose routing?

 

[joeninpo]

Actually, I think that my fuel problem is solved...I tried to start it this morning with a fresh battery, and although it wouldn't start, I did have good fuel flow. So, problem one is solved as far as I can tell.

Unfortunately, somehow between last night and this morning, I lost my spark! I usually check three things automatically when I tear into something...fuel, spark, and air. So, this morning when it wouldn't start again, and just to make sure that I wasn't doing something horribly wrong, I checked spark at the plugs. Nothing.....so I guess I'll see you guys in a different part of the forum here in a few minutes!

A few other things to add here just for future reference and to help some others out with similar problems, the 1980 fuel petcock on the 550s is a vacuum petcock and it does not have a normal selection lever on it. You can use a small screw driver and change the settings from full horizontal to full vertical. The full horizontal is the normal position and the full vertical is the prime position. In the normal position, fuel flows when the petcock encounters vacuum supplied from the engine through the smaller hose on the petcock. It should not flow otherwise. The engine should provide enough vacuum when you are starting the bike to open the petcock, and you should not have to put it into prime except for a few odd circumstances. If you do need to put it into the prime position, fuel should flow regardless of vacuum or no vacuum. When you put it into prime, fuel should flow freely, which can cause some serious problems when your engine is sitting and the fuel is just constantly trying to make its way into your engine. It does have its uses, though, so be sure that you can move the petcock from normal to prime just in case you ever need to use it. This may have been discussed in a different thread on this forum, but I couldn't find it all in one spot, so I just thought that I would recap for you all.

Thanks again for all the help and I'll talk to you all soon!

Eddie

 

[KEITH KRAUSE]

The petcock info in the 1980 GS1000 factory manual says you must crank the engine to initiate fuel flow, even in the prime position. Just saying what it states even if it doesn't seem to make sense (we've discussed this long ago). I can't say if the '80 550's petcock is different.

 

[gsbobber]

shuts off

shuts off

sorry for using this post to ask the question but for some reason it wont let me make my own thread and this looks some what familiar to my problem. i have a 1980 gs750l and my problem is sometimes (every time i was on the freeway) ill be driving then i feel my bike sputter a little then it shuts off i have full tank of gas. i let it chill for a few min then it starts back up no problem. but i have to let it sit or else it wont start it cranks but dont start

 

[gustovh]

sorry for using this post to ask the question but for some reason it wont let me make my own thread and this looks some what familiar to my problem. i have a 1980 gs750l and my problem is sometimes (every time i was on the freeway) ill be driving then i feel my bike sputter a little then it shuts off i have full tank of gas. i let it chill for a few min then it starts back up no problem. but i have to let it sit or else it wont start it cranks but dont start

Heat short. Check your wiring for good connection and cleanliness.
V

 

[Colorado85gs550]

I'm in the process of redoing all of the wiring on my bike.....although since your bike is sputtering before it dies at mid to full throttle on the highway I would say yours is sounding like a petcock issue!! Yours is able to fill the bowls after sitting for a few minutes then will supply fuel until you use the fuel faster than it's able to fill them due to not creating enough flow due to a bad petcock.

When mine would die, it just dies. No sputter, nothing. Like I hit the kill switch and you can hear the starter clutch cycle. OVER..........

 

[Suzuki_Don]

sorry for using this post to ask the question but for some reason it wont let me make my own thread and this looks some what familiar to my problem. i have a 1980 gs750l and my problem is sometimes (every time i was on the freeway) ill be driving then i feel my bike sputter a little then it shuts off i have full tank of gas. i let it chill for a few min then it starts back up no problem. but i have to let it sit or else it wont start it cranks but dont start

Check the breather hole in the fuel cap. If this is blocked the gravity feed to the carbs will be affected. If the tank cannot breath then a vacuum is created in the tank above the fuel instead of atmospheric pressure. You need good atmospheric pressure inside the tank to get the gravity feed required.

 

[gsbobber]

thanks........

 

[gsbobber]

how do u check it

 

[Danjal]

Pull the lines off of the carbs and just blow through them. If you can its good. If not its blocked. For your tank just open up the fuel cap to test it. If it works great and runs great and dosent stall.. that might be your problem. Just reace it and see if it dies again.

Usually if the carbs are blocked they'll keep sucking more fuel into them and flood the engine.