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Discussion Starter · #1 ·
Hi. My name is Quinten. I recently got a bike handed down to me from my father and it has sat for about 5 years. It is a 99 Honda Shadow VT750 with only 5k miles on it. I have previously worked and restored other bikes but this is my first shadow that I have worked on. I started by replacing the battery and then the bike started up with some starter fluid in the air box and it would run for a few second and then sputter out. So I took out the carb and did a deep clean and rebuild on it (which I am always very thorough with and use an ultrasonic cleaner and everything). I put the carb back in the bike and sprayed some more starter fluid in it to get it moving and same result. Only started for a few seconds and then sputtered out. I replaced the spark plugs and I know it is getting good spark as well as good compression. So I opened up the drains at the bottom of the carb to pull it out again and do a second cleaning and nothing came out. I have dissected the fuel tubing and the petcock works well (albeit a gravity fed petcock) and there is an inline fuel filer that fuel is getting through well. But, when I got down to the fuel pump (or fuel solenoid, im not sure which it is) the gas goes in, but when I turn the petcock to on, fuel barely dribbles out of it. Is this normal? Im not used to have a fuel pump, normally the bikes I have worked on only have a gravity fed line straight to the carbs. Is there a way to test if the pump is working? Do I need to replace it? Should I just bypass the pump?
Sorry for the longer post, just trying to get in all the details and what has been done so y'all know what I have already done. Any suggestions help. Thank you so much!
 

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1983 Honda vt750 Shadow
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The fuel pump has a safety relay to shut off the fuel when the bike falls and the key is still on.
It gets a signal from one cylinder to tell the relay the engine is running.
Take the hose off at the carbs and crank the engine and the pump should run.
You can put battery power to it also to test the output.
About a pint in 15-20 seconds or so is common.
 

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Discussion Starter · #3 ·
The fuel pump has a safety relay to shut off the fuel when the bike falls and the key is still on.
It gets a signal from one cylinder to tell the relay the engine is running.
Take the hose off at the carbs and crank the engine and the pump should run.
You can put battery power to it also to test the output.
About a pint in 15-20 seconds or so is common.
If I were to just leave the output hose off of the pump and crank it over would it have the same effect? I just rather not have the finesse the fuel line off of the carb is all. Also I take it that if I crank the engine and fuel does not come out, then that means I need to replace the pump?
 

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Have you tried jumpering out the fuel cut relay? If not, under right side cover, black, black-blue and yellow blue wires. unplug it, jump black (Power from key) to Black-blue (power to pump) in the harness plug, tape it up

Once jumpered, when you turn the key on, pump should run a few seconds until the bowls are full, slow down and cut off flow. Or for test purposes, direct the output into a container, turn key on, should pump around a pint in 20 seconds. or so. There are actual amounts and number of seconds to use in the manual.
 
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The fuel cut relay is a safety device, it is triggered off one of the ignition coils so the pump stops if the motor dies.
 

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Discussion Starter · #6 ·
The fuel pump has a safety relay to shut off the fuel when the bike falls and the key is still on.
It gets a signal from one cylinder to tell the relay the engine is running.
Take the hose off at the carbs and crank the engine and the pump should run.
You can put battery power to it also to test the output.
About a pint in 15-20 seconds or so is common.
So I took the hose off the pump and tried cranking it over and got no fuel coming out of it. I didn’t jump it, just used the battery from the bike to start it up and it cranked over plenty so i imagine that is fine. so because of this I imagine this tells me I just need to replace the fuel pump?
Im still a little confused though. Because I’m all the other bikes I’ve worked on, if you turn it to reserve then it fills the carb bowls. Does this bike just fill the carb bowls only from the fuel pump?
Thanks for all the help!
 

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'83 VT750C; ‘21 SV650A
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You'll notice that the carbs don't sit all that far below the tank, so the pump is there as a precaution. Some have converted to all gravity feed, though you have to watch how much fuel is getting to the carb at higher speeds (more fuel demand). It's easier to just test and replace the pump if necessary. The last test you can do is to take two wires. Run one from the positive terminal of you battery to the positive pin on the pump. Then take the other wire from the negative terminal of your battery and touch it to the negative pin on the pump. The pump should make some kind of noise, gas getting to it or not.
 

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If the relay is bad, it won't pump at all, you have to jump it to find out if it's the pump or relay.

It should not take more than 20 or 30 seconds max to get it primed. don't run the pump too long if it's not flowing.

Edit: you have to bypass the relay by jumpering the black to black-blue wires in the relay's harness plug. half a paperclip works. tape it up. Also might find the pump's ground connection and clean it. verify a good ground.
 
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