Waking a VFR700 - Fuel questions...

[RadHawk]

So a buddy of mine had this '86 VFR700F languishing in the cellar and he wanted to get it going... Great.

Old gas, brittle fuel lines, weak clamps, plugged up fuel filter, all that changed out. Checked for spark, I did not check compression.

With a new battery I cranked her up for a bit and no joy so I pulled the fuel line off just ahead of the pump and there is only a trickle. Emptied the tank and pulled the fuel tap off to ensure that the internal piping was not partially blocked and reassembled. This fuel tap is that recessed little number set into the left side of the tank. Not a bad set up really. Three O-Rings under the valve itself, no leaking.

Does the pump need to actually suck from the tank or is the gravity feed from the tank enough to fill the pump and push the fuel to the carbs...?

As an added oddity, the pump relay clicks when I hit the go button but I do not know if it should or not...?

Thoughts...?

Thanks,
Rob

[Tekime]

Never touched a VFR but is there fuel in the carbs? If so problem might lie elsewhere. Gravity feed might be enough for a start but not sure about running. Clicking would indicate a working relay but doesn't rule out a bad pump.

[RadHawk]

Never touched a VFR but is there fuel in the carbs? If so problem might lie elsewhere. Gravity feed might be enough for a start but not sure about running. Clicking would indicate a working relay but doesn't rule out a bad pump.

Yeah, I am not certain that sufficient fuel is getting to the carbs based on how much of a trickle was coming from the tank to the pump. When I "Tested" the pump, I pulled the outlet line off the pump and cranked the starter, a little fuel came out, about the same stream as the trickle from the tank. As I would let off the starter a larger amount would flow out... LOL

Is there an honest to goodness test for the pump or was that it...?

Before I pull the carbs I would like to be certain that I have good flow to and out of the pump. I really should open the carbs as I do not know how long she sat... still getting fuel there is the issue right now.


Thanks,
Rob

[Bonk!]

might try posting on VFRWorld: VFRworld

[RadHawk]

might try posting on VFRWorld: VFRworld

I just registered... thanks,
rd

[jasnmar]

Grab some clear fuel line and see if you can see what's going on.

Usually with these the Fuel Pump provides a very minor boost in pressure, just enough to make sure the bowls are filled, that said, they can trick you. I had a fuel pump go out on my CBR. Only after doing a lap on track would it actually "run out" of fuel. If you are just getting a trickle, there's probably a problem. It should pour (at least from my experience with a CBR).

[RadHawk]

Grab some clear fuel line and see if you can see what's going on.

Usually with these the Fuel Pump provides a very minor boost in pressure, just enough to make sure the bowls are filled, that said, they can trick you. I had a fuel pump go out on my CBR. Only after doing a lap on track would it actually "run out" of fuel. If you are just getting a trickle, there's probably a problem. It should pour (at least from my experience with a CBR).

Right, I would think that more than a trickle should come from the tank. Good to know that the pump is really just a boost.

I did put a clear in-line filter in place of the metal canister type just to prove that I had flow, the intent was to swap it back out after I got it running although I am not sure that I need to.

Since pulling the fuel tap off and blowing compressed air though the openings, I have not re-fueled and tried it, I will tonight... Mother's day and all that , ya know...

I am actually tempted to hang an auxiliary tank to fuel it for starting but I need to be assured that the flow problem is cleared up as well.

Thanks jasnmar,
Rob

[jasnmar]

I've found https://www.motionpro.com/product/08-0032 incredibly handy.

[RadHawk]

I've found https://www.motionpro.com/product/08-0032 incredibly handy.

Yup, I have the very same tank... the outlet pipe ( I would call it a nipple but I know how you guys are... lol ) is broken off so I need to find a way to repair it and still use an in line fuel tap on it.

So, to that same subject, I do not need to have the VFR tank in place to fire it up...? The system does not require some pressurization or some such nonsense...?

Thanks,
Rob

[jasnmar]

I don't have experience specifically with the VFR, but my later model CBR did not. I could get it to run just fine by going around the pump and filter, just running from the aux tank straight to the carbs. Pump was only necessary under load.

[RadHawk]

I don't have experience specifically with the VFR, but my later model CBR did not. I could get it to run just fine by going around the pump and filter, just running from the aux tank straight to the carbs. Pump was only necessary under load.

Oh, of course, by pass the pump... Seems I am awake. Geez, what a bone head.

There is still the flow from the tank which I hope has been cleared after the cleaning, I will know tonight.

Thanks,
Rob