Sometime sooner or later, the mechanical fuel pump on the GL1100 is going to give up the ship. Mine started to leak out the weep hole on our last trip.
Taking off the fuel pump is pretty straight forward since it hangs off the aft end of the right cylinder head. Rather than take the two 12mm bolts off the "neck", take the whole assembly off at the head (10mm head bolts) the inboard bolt also holds the tachometer cable in place.
The 12mm head bolts hold the pump to the neck. There is a black spacer in between the two, and that is needed to put everything together again so don't damage it. If it's stuck, use a gasket scraper rather than a screwdriver to pop it loose. When you order the pump, order the gaskets too because they don't come in the box. Carefully use a razorblade to scrape all the old gasket material off to leave clean flat surfaces for the new gaskets.
Putting the pump back on is a little different than taking it off. The pump arm runs off an eccentric that is a part of the end of the camshaft (the worm gear for the tach cable is there too). Grease everything before assembly, because there is no oiling coming from the engine in this area. Put the neck piece on and rotate it towards you to make the pump easier to mount.
Note: the o-ring you see on the tach cable end is my idea, not a Honda part. I did it to keep the weather out of the area above the drive seal. If you do it, the o-ring needs to be skinny enough for the bolt to pass by it.
After mounting the pump to the neck piece, you can rotate the assembly into place to line up the bolt holes. Put in the outboard bolt first (finger tight) to hold everything together. Insert the tach cable into its hole, then put the inboard bolt in to finish. If the tach cable won't seat, it's because the blade isn't lined up with the mating slot. Use a small screwdriver to turn the cable slot to align.
You are now free to hook up the fuel lines again. Test n' Check before heading out of the garage on a ride.
What caused all this was the gas cap. The tank vents through the cap and nowhere else. If the vent in the cap goes bad, vacuum builds up in the tank to the point of stopping fuel flow. This will probably happen when the tank is almost empty and there is a large vacuum above a small amount of fuel. This happened to me when switching to reserve, and Murphy's Law dictates it will happen out in the middle of nowhere.
The new parts photo from Honda Parts Direct included a gas cap. This is a supercession to the original, but it fits.
To get me though the remainder of the trip since we were 1100 miles from home, I drilled a small hole through the top of the cap as a temporary measure, but this new cap is better for a permament repair.
Thanks to Honda Parts Direct, I had a new pump and gas cap (the vent valve was stuck too) to put on the bike this morning. Fuel pump was $78.39 and the cap was $22.91
Last edited by MSGT-R
on Sat Jun 13, 2009 10:16 am, edited 1 time in total.
Don't spook the road sheep.