Hi,

I have a 1990 Tenere that is not running off of its reserve tanks. There is fuel in there, sloshing around, but it apparently can't get to the motor.

First, I don't know much about motorcycles. But this much I do know:

1. It's not vapor lock. Still happens with no tank cap on.

2. The petcocks work great and are clean.

3. There is only a moderate amount of small particles in the tank - fuel draining out of the reserves is fairly clean.

4. Three shops in two different hemispheres have not been able to fix the problem. But for one tank after they do whatever they do, the reserves flow and it works. But after that, the same problem.

A wise friend of mine took most of the system apart for me, and theorized that the the reserve tank level is just below the carburator, therefore with low levels of fuel there is not enough pressure to force the fuel "uphill" to the carb, hence what looks like a small pump in the fuel line that may pump it up. It's apparently a vacuum pump.

So his ideas are: 1. Replace the pump or 2. Add a small auxillary pump to help the flow along.

Is this a common Tenere problem? Help! My range is only about 300 K without reserves...hardly enough for Death Valley. Or Alaska. Or....

Thanks in Advance,

David


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What you think is the pump, is the pump. It works on pulsating vacuum from the inlet manifold.
If you have a full tank, have the engine running and pull off the hose to the carb. If fuel spurts out in jets the pump is ok. If not, repair / replace the thing.
Also, make sure that all connections to / from the pump are ok. There's arrows for fuel in, fuel out and one without arrow. This last one is for the connection to the L/H inlet. On top of the carb rubber connection to cil head there's a hose connection. Hose should go from there to pump, unmarked connection.
Pump could be not-functioning through dirt blocking movement of the valves.

Auke

hi david,

yes, this is a common 1VJ and 3AJ problem.
the pump is a trouble maker. in the worst case it may allow fuel flow directly into cylinder, omitting the carb (via vacuum hose).
my advice is to remove it completly.
the unused amount of fuel is neglectable, about half a liter or so.

best regards,
klaus
xt600.de / tech. dep.

Happened to me at 0430 just off the boat from tangier. The pumps are prone to die just rejig the tubing to gravity feed the tank and bin the pump.

CC

Thanks so much guys for your information.

I will go back into the fuel system and try out the solutions...what a great forum!

David

Thanks to the advice offers...they helped solve (I think) the problem. I ended up installing a 12v pump in the fuel line. Of couse this interfered with the fuel flow, but I put two extra "T"s in the line so there would be a smoother line around the pump....and it seems to work! I installed a switch on the dash, too, so when the main tank runs dry, I hit the switch and that seems to get the flow started.

David