Engine not sacking gas

[Redbeard]

So I have an 81 Gs 1000 and it runs when I put gas directly into the carbs but when I hook up the gas tank it doesn't want to suck in the gas. Any ideas?

[Charlie G]

Is the vacuum operated petcock working properly allowing the fuel to flow to the carbs?

[Datsa Noydb]

Looking at your other two posts, it appears that you are not all that fluent in mechanical things, maybe just the GS aspect of that. Post your location, there might be a member close enough to stop by and give a hand.

I also am curious about the term "sacking", as you use it in both of the threads you have posted in. The term "sucking" could have been used in both cases, but the 'u' is not close enough to the 'a' on the keyboard to call it 'a fat-fingered typo'.

I agree with the possibility of the petcock not working correctly or possibly not even being connected.

[Redbeard]

First of all I'm using my phone on this website so autocorrect Is making me his b**** lol. Also I'm not a huge motorcycle mechanic I am definitely more of an automotive type of guy but I bought this bike to try to broaden my horizon on engines. And I'm in surprise Arizona. And how would I check to see if the vacuum is working?

[8ball]

Put the petcock in the "on" position. Disconnect the two hoses from the petcock to the carbs. Gas should not flow from either port. The small one is the vacuum line, and the large one is the fuel supply to the carbs. Put a small piece of hose on the vacuum port of the petcock. Hold a cup under the fuel port and suck on the vacuum line. Gas should flow from the fuel port. Gas should also flow in the "PRI" (prime) position. but that should only be used when first starting the bike.

[Big T]

He's probably got the infamous leverless petcock -does that have a Prime position?

Lesson 2 - the engine doesn't suck the fuel, it's gravity feed

[Who Dat?]

He's probably got the infamous leverless petcock ...

I have only seen them on '80 models, not the '81 he is working on.

[Who Dat?]

First of all I'm using my phone on this website so autocorrect Is making me his b**** lol.

My condolences on not have a REAL computer available, and having to settle for a pocket-sized version.

Regardless, "autocorrect" is actually "autoSUGGEST", as you don't have to accept what is suggested.

YOU are the one that determines what is there, BEFORE you hit the "submit" button.

[hockey911]

Set petcock to prime (PRI)

Then figure out the vacuum problem....


The petcock will release gas (hopefully) in the on position when a vacuum is applied to the petcock..... it draws the vacuum from the carburetors (not exactly sure where the connection is on your bike, on my gs450 the connection is on the rightmost carb)

[Guest]

First of all I'm using my phone on this website so autocorrect Is making me his b**** lol. Also I'm not a huge motorcycle mechanic I am definitely more of an automotive type of guy but I bought this bike to try to broaden my horizon on engines. And I'm in surprise Arizona. And how would I check to see if the vacuum is working?

Don't be a bitch to your phone. That's exactly what it wants. Show it who's boss!

If you suspect petcock, they are pretty inexpensive on Ebay. I had to buy one for mine.

[jdvorchak]

I have a 1980 and it has the leverless petcock and it is my understanding that it does have a prime but you have to select it with a screwdriver.

[Guest]

It does, though it might as well not. There is a little nylon screwdriver slot. Horizontal is vacuum, perpendicular is prime. There is no stop so you still have to double check the horizontal position and tweak it a bit to make sure fuel is not flowing from the prime position.