85 gs700e fuel carb question

[AJKnowles700E]

Alright, I am stumped. My question is this, fuel will not flow from my tank to my carbs on prime, however I have tested the petcock and that works perfectly. Even with the tank off I added fuel through a funnel into the fuel line to the carbs and it would not flow. Took float bowl drain screw out and tried the funnel trick again and it flowed beautifully. It seems as though there is some sort of vaccuum issue going on here but I am not sure as how to resolve it. If anyone has any ideas at all I would be greatly appreciative. Dying to get her running but keep coming up against walls. Thanks for help


AJKnowles

[AJKnowles700E]

may have found my answer but if not please feel free to add suggestions still.
Thanks again

[renobruce]

If the bowls are full, it won't add any more. If you took the drain plugs out and it started to flow, that's because the floats are dropping and opening the needle valves to allow more fuel in. Check your float height. It should be 22.4mm. Or if you have the means, hook up a tube in place of the drain plugs and measure how much gas is actully in the bowls.

Also, your carbs have two vents that go to atmosphere... are they plugged or hooked up to anything? The center nipple is for you petcock, the two outer ones are vents.

[AJKnowles700E]

If the bowls are full, it won't add any more. If you took the drain plugs out and it started to flow, that's because the floats are dropping and opening the needle valves to allow more fuel in. Check your float height. It should be 22.4mm. Or if you have the means, hook up a tube in place of the drain plugs and measure how much gas is actully in the bowls.

Also, your carbs have two vents that go to atmosphere... are they plugged or hooked up to anything? The center nipple is for you petcock, the two outer ones are vents.

This is all true but if the float bowls are empty then when on prime, fuel should flow freely into the carbs to fill those empty bowls but it does not flow it.

Which parts are the vents for the carbs to the atmosphere? I cleaned them piece by piece last year and thought I was good to go. Thanks for the reply

[Nessism]

Check this link to see how the vent hoses are routed on a GS850, your bike is similar http://members.dslextreme.com/users/...locations.html

[Billy Ricks]

If it's not flowing fuel on prime that problem is caused by a rod with about a half loop of spring built into its base. It's on the back side of the valve that controls run and reserve. It tends to get shorter with use because of the spring. Take it apart and lengthen it to make the prime function work. You can go too far in lengthening it so test it while it's off the bike to make sure you get it right. Just suck on the fuel line in prime position to see if it allows air to pass. Then turn it to run or reserve and you shouldn't be able to suck air through. Before going to the trouble make sure the prime function doesn't work.

[Steve]

Are you reading the petcock correctly?

You have to look at it carefully, but the desired function is the one that is covered by the pointer.
Regardless, when the lever is pointing BACK, it's on PRIme.
When the lever is pointing DOWN, it's on RUN.
When the lever is pointing FORWARD, it's on REServe.

Just be thankful you don't have the dreaded petcock from 1980. Those things should have never made it onto a production bike.

.

[AJKnowles700E]

Yes the petcock is in the right position I have had that figured out for a couple of years. I think my next quest is to see if the vents on the carbs are plugged. I am getting real good at removing and replacing this blessed things now at least. Thanks for your help will keep updated

[Smokinapankake]

Maybe check to see that the gas tank is venting. My old GPz had this problem until I cleared the vent in the fuel cap. One way to check is to open the cap, see how much fuel flows.

[AJKnowles700E]

All fixed now, must have been the gnomes! I left it over night since I was frustrated with not being able to fix it and the next day it started right up and runs beautifully! Thanks for all your advice and quick replies!

-Adam