Getting a 78 GL1000 going after a long sleep. Changed the timing belts, fluids, and fuel filter. Tank has been derusted and I have fuel flow through the petcock, and can hook a vacuum pump to the outlet side of the filter and pull fuel through it. I have nothing coming out the outlet side of the pump so I took the top off of it for a look see. The one way check valves both seem to do what they should and I can't see any tears in the diaphragm. My genuine Honda manual is kind of short on fuel pump details, like what drives it and how (where?) it's removed from the head. Any advice would be greatly appreciated.
MikeG
fuel pump issue?
Re: fuel pump issue?
The pump runs the same as older automotive style pumps. There is an arm that rides a small bump on the camshaft which moves the diaphragm up and down. It is easy to pull off and operate manually to check.
After any long sitting, I find it helps the battery and starter to pull the feed to the pump and bypass it straight to the carbs to let the bowls fill up. Others use a big syringe to push fuel in. You need over a half tank of fuel for the fuel to flow to the carbs without the pump. The lower half of the tank sits below the carb level. If you don't do this it takes a fair amount of cranking to get one cylinder to start, then two, then three, then it takes off. Priming them eliminates this. I have seen a few Wings with marine prime bulbs on them.
After any long sitting, I find it helps the battery and starter to pull the feed to the pump and bypass it straight to the carbs to let the bowls fill up. Others use a big syringe to push fuel in. You need over a half tank of fuel for the fuel to flow to the carbs without the pump. The lower half of the tank sits below the carb level. If you don't do this it takes a fair amount of cranking to get one cylinder to start, then two, then three, then it takes off. Priming them eliminates this. I have seen a few Wings with marine prime bulbs on them.
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- Posts: 30
- Joined: Fri Jul 22, 2016 1:05 pm
- Location: Hillsboro NH USA
- Motorcycle: 1978 GL1000
07 Suzuki Bandit
61 BSA A10
71 Norton Commando
Re: fuel pump issue?
Thanks for that. Was not aware that that much fuel was required before it would gravity flow into the filter. I had only put about a quart in for test purpose, and I'm glad I did as half of that was on the garage floor this morning. Looks like I get to experience the joys of fuel tank removal now. 

- SnoBrdr
- Posts: 784
- Joined: Fri Mar 07, 2014 9:01 am
- Location: Providence, Rhode Island
- Motorcycle: 1978 GL 1000
131K Original Owner
Re: fuel pump issue?
Removing the tank isn't that bad if the bike is naked.BSArider wrote:Thanks for that. Was not aware that that much fuel was required before it would gravity flow into the filter. I had only put about a quart in for test purpose, and I'm glad I did as half of that was on the garage floor this morning. Looks like I get to experience the joys of fuel tank removal now.
Basically the back half of the bike, tire, shocks, etc have to come off.
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- Posts: 30
- Joined: Fri Jul 22, 2016 1:05 pm
- Location: Hillsboro NH USA
- Motorcycle: 1978 GL1000
07 Suzuki Bandit
61 BSA A10
71 Norton Commando
Re: fuel pump issue?
Thanks...been reading up on tank removal, and as you say not hard just a lot of stuff to come off. Much like my 71 Norton Commando,where horn replacement requires dismantling the rear half of the bike just to put your hand on it
Re: fuel pump issue?
It will flow to the filter and to the pump with only a few ounces of fuel. It won't flow up into the bowls of the carbs. Good to know if it dies on the road. You can fill it and ride about two gallons worth before needing fuel.