[B]Fuel Pump Diagnosis[/B]

[tycrazyjohn]

I know this question has been beaten to death on this forum, but I honestly can't find the answer I'm looking for. I've been rebuilding a 1985 VT700, and my newest issue is that I'm not getting fuel to the carbs. I connected a hose to the nipple on the float bowl and backed the screw out, and when I short the fuel pump it clicks away rapidly, but no gas ever comes out. I'm assuming I'm connecting it right, in order to bypass the relay I simply put a jumper wire in the connector. I have fuel at the filter, I can see it's half-way full of fresh gas. But whenever I put power to the fuel pump it just clicks really really fast. I have a video if anyone wants to see. So is the fuel pump shot? I figured not since it worked fine before the rebuild and it clicks like normal.

[tubes_rock]

Fast clicking is usually a sign of fuel not getting to the pump. Does the input side of the pump has fuel supplied to it? (If you pull the input hose off of the pump, does fuel flow by gravity?)

--Justin

[tycrazyjohn]

Well I won't be able to actually pull the hose off until this weekend. The only thing I could tell was there was fuel getting to the filter, and there's only a short hose in between the filter and the pump. It's possible that hose is sitting at a funny angle and not letting fuel through it...if that's the case I'll try to find a new way to route it

[John Hopkins]

The clicking sound you hear is possibly an empty fuel pump..once the system is full the clicking is muted..so what is stopping the pump from giving fuel to the carbs..from the tank you have a tap with the possibility of blockage from muck in the tank or the tap itself..(an added complication on the VT700 is that there is another tank.) if you disconnect the tap hose to the fuel filter and turn the tap on does fuel pour out...it should...then the hose goes to the fuel filter..is the filter clean..then it goes to the fuel pump, is the hose kinked stopping the fuel reaching the pump..if the fuel reaches the pump there is only a lead and T joint to the carbs so if it doesn't reach the T joint then the pump is the fault..

John.

[tycrazyjohn]

Finally have an update with this issue, last weekend I messed with it some more and turns out when I pull the hose from the filter off the pump fuel flows nice and freely. Then when I hook it back up to the pump and disconnect the hose leading to the carbs, nothing. So I guess the pump is shot :/ I'm just really surprised because it worked fine when I starter my rebuild. Ordered the new pump (not cheap either) and hopefully I'll get to test it out this weekend.

[cl65ame]

Make sure the pump is PRIMED. In order for it to pull the fuel through the filter the pump needs fuel in it already to get things started. usually it primes itself by gravity bu it seems not.

[bigooomp]

makes me glad im changing to vacuum with my s&s carb one less electrical piece to bomb out on me

[tycrazyjohn]

How would I go about priming the fuel pump? I thought since fuel is flowing to the pump already that should prime it?

[tycrazyjohn]

Just wanted to give an update so if anyone comes along and wants to know how it turned out, I put a brand new fuel pump on it and it works perfectly now!