750 won't stay ruinning

[minisid]

couple weeks ago I loose power going to work after riding 1 miles. The bike would start but not stay running.

After investigation I found out that the fuel did not come out the fuel pump.

I replace fuel pump and fuel filter last week end. Charge the battery as it was weak. I ride for about 5 miles with no issue. Then I stop, put more gas in there for a longer run. The bike die on me after 1 miles.

The bike start but die right away if I use throttle. If I don't use throttle it will run for few seconds before dying.
If I put gas directly into the carburetor it will run fine.
It have check the spark plug, and it spark
Fuel is coming out of the fuel pump
there is vacuum at the fuel pump and the petcock.

anyone have suggestion here before I send it to the shop?
thanks

[terse750]

You said you checked to make sure the gas tank vent line is not kinked?

Thats the cheapest problem to fix!   electrical?

[tbyte]

Has it been out in the rain?  Drain some fuel from the floats and check for water.

[Howie]

When the bike stalls open the fuel cap and restart.  If the bike now runs it is a venting problem.  Still doesn't run you have another problem. 
Drain the carbs into a clear container.

Fuel comes out here


Clean fuel?  Bypass the petcock.  Still doesn't run?  Bypass fuel pump and fill tank over the height of the carb float bowls.  It should now run by gravity feed.

[minisid]

thanks guy for all the answer.

-I did try to open the gas cap and it does not run, so it is not the vent.
-it does have been in the rain, it sleep outside (I know I am bad ), I did not see water in the gas but I will check again in case. If I put gas (same than the one in tank) directly in carbs it will run.
-I did not try to bypass the petcock as I have gas going into the pump, but I can try to do that too.

I will try all that tomorrow, getting late today.

[minisid]

you guys rock! I don't know why I did not think about that earlier, found water in the gaz, well actually at this point it is gas in the water   

this is out of both carbs. thanks howie to show me how to drain those.

Now I need to empty the all bike of all gas. Then I need to found where the water come from and I have a pretty good idea. The gas cap leak gas when the tank is too full and lift up, so if gas can get out, I am pretty sure water can get in. So my next quest will be to find out how to fix that, I hope the screws are not strip on the cap.

thanks again

[tbyte]

It is not the gas cap.  There is a drain under the gas cap that is clogged.  If you must leave it out in the rain put a plastic bag over the tank.  You might try snaking the drain with an old speedo cable or something similar.  Of course if you puncture the drain tube the tank will be worthless.

[Raux]

Bet you your overfill tube fell off

[Howie]

The vent is a couple of check balls and a spring.  Make sure the overfill drain is clear and the seal on the gas cap itself is good.

[minisid]

the seal under the cap seams to be missing to me:

did you know what kind of seal go in there (size)?

I put my finger inside the tank and the hose for the drain is still attach on the top. I was wondering if I can pour some water (or gas) inside the tube and see if come out the other end of it.

also there is some kind of gasket over the drain tube that is higher than the hole for the tank, I was wondering if it is suppose to be that way.

[Raux]

Blow air only

[Howie]

Blow air only

Yep, last thing you need is more water.  Seems the gasket is not available as a part.  You might need to buy a new cap or make a gasket from a sheet of rubber.

[Raux]

Were there two hoses in the tank? One should be a vent, lines up to that tiny hole on the cap. The other to a hole on the kickstand side.

[minisid]

Were there two hoses in the tank? One should be a vent, lines up to that tiny hole on the cap. The other to a hole on the kickstand side.

found it thanks


I check the overflow drain and it is not clogged, I send air in there and air is coming at the other end.

I was wrong the rubber seal is still on there, probably was tired last night. However I notice when I close the cap it come back up a little bit. Don't know if it suppose to do that or not.

I drain all bad gas, detach the tank and remove the drain cap. I put new gas in and it start and stay running little it should. I will send it for a ride tonight or tomorrow when I know someone can come get me if I have a trouble again.

I will get a waterproof cover but I still don't know where water can get in. I put some WD40 in the key hole of the gas cap and it drain on the bottom, I wonder if that could be my leak.

I forgot, while draining all the augs and stuff something fell of the bike

was when I was behind the breather on the right side. Did someone know where that goes?

[Raux]

I think you have a split overflow tube. It allows water in and gas out...