Fuelling Issues

After a long layoff period, my ST1100 wouldn't start. I cheated with some Easystart and it fired up for a second or two. I tried some more without Easystart, but it didn't want to know. I have compression and a spark, but noticed the plugs were dry.

I've assumed the carbs have clogged up and removed them for a good ol' clean tomorrow.

My question; With the fuel pipe to the carbs removed, I spun the engine over. Fuel came out, but only a dribble. Is that normal? I ask, because I don't want to chase a problem that isn't there.

Ta chaps

There is a vacuum operated fuel cut off valve on the right side of the fuel tank exterior, near the fuel filter. Without any vacuum going to it, the fuel pump can't pump fuel through. If you were to apply some suction to the vacuum hose, it should open the valve and allow fuel to pump with the ignition on.

Bush said:

There is a vacuum operated fuel cut off valve on the right side of the fuel tank exterior, near the fuel filter. Without any vacuum going to it, the fuel pump can't pump fuel through. If you were to apply some suction to the vacuum hose, it should open the valve and allow fuel to pump with the ignition on.

Click to expand...

I did the vacuum by-pass some years ago (ie, it doesn't have one).

So, is the fuel pump pumping with the key on then? If only a dribble, sounds like a pump problem.

Bush said:

So, is the fuel pump pumping with the key on then? If only a dribble, sounds like a pump problem.

Click to expand...

Should it be more of a jet?

From my service manual: Fuel pump flow minimum capacity: 640cc (0.563 Imp qt) per minute

It also says: Turn the ignition switch ON and let fuel flow into a graduated beaker for 5 seconds, then turn the ignition switch OFF. Multiply the amount in the beaker by 12 to determine the fuel pump flow per minute.

Maybe the fuel filter is clogged from stale gas?

Until the engine is running the fuel pump will only run for a few seconds after the ignition is turned on. So don't expect to see more than a dribble flowing after a few seconds. If you want to test your fuel pump, you will need to run a wire from the + terminal on the battery directly to the fuel pump. Make sure you connect the wire to the correct terminal !!

I would also remove the fuel filter and check to see if it's clogged.

+1 What Jim sez.

To test the fuel pump, disconnect the white plastic connector on top of the tank and jumper from the battery pos+ post to that spade. Also helpful to pump out fuel to make it easier to remove a (lighter) fuel tank. BTDTx5

John

I would definitely test your fuel pump in situ as suggested above, preferably without the filter, using a jumper from the battery + to the spade. With each cycling of the ignition or kill switch You should get a healthy squirt rather than a dribble. The fuel pump has a very fine mesh screen and yours may be varnished from old fuel. It's not a big deal to remove the fuel pump from the tank for inspection and/or external testing.

Hey guys, I stripped the carbs down. The float valves were gummed solid. Put it all back and fuel was pouring out of the vent on one of the carbs. Took it off... AGAIN... couldn't see anything wrong, but cleaned it all up some more- lots of squirting cleaner through the drillings, etc. Seems ok now. Bike runs pretty lumpy, but all the pipes are off, plus it hasn't run for about 3 years.

I'm cautiously optimistic