Fuel pump question

Hi all, sorry I haven't posted for quite a while, the VFR has been stuck outside under a cover as I just have not had the time to get her sorted. Trying to get some life out of the engine, my son and I drained the carbs, and poured some solvent cleaner into the open carb inlets, (we had removed the airbox), and then drained again. Primed the carb bowls with fresh petrol, (gas to you guys ), then prepared to start the motor. We rigged up a supply to the inlet, as the tank was off of course. Cranking her over didn't elicit much response, though to be honest the battery shows just over 12 volts, I don't think it's very strong. She caught for a second or two, but then nothing. I noticed there still seemed to be fuel in the filter, and wondered if the pump was doing it's job. We tried bypassing the pump with a supply direct to the carbs, and the pump spat a couple of times.
So the main question is, with no pressure of the float bowl needles holding up supply, should the pump just try to run flat out? Do I have a sticky pump, and is there some way to test it?
I'm going to put the battery back on charge in the garage.

Cheers, Tony.

 

Your battery may have just enough juice to turn the engine over, but not have enough left for spark.



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Hi, yes we did wonder about that. We tested for spark and there was one, but as you say, the battery has been sitting for a while with just an occasional boost charge, that doesn't do it any good!

 

Ah, just found how to check pump by bypassing the cut-off relay in the Haynes manual. I shall try that tomorrow once the battery has had a good charge.

 

It should still fire up with a gravity feed tank.

Unless the cylinders are not getting fuel.



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Yes, I think the battery may be the main problem, ie lack of a decent spark. We shall keep going and see what's what, cheers.

 

If your pump is good it will try pumping as soon as the ignition key is turned on. If it is starved of fuel it will click loudly and more rapidly the longer it stay on running without fuel.
I always run a jumper any more after I relied on mine to work properly and promptly fail on my first road test. Now I get a friendly reminder when I go on rides that my fuel tap is turned to the off position.
Hope that helps solve whether it is a pump issue or not.

 

If your bike has been parked up for some time there's a good chance the low speed jets (i.e. the ones that the engine needs to run at low rpm) will be clogged as they are amazingly tiny. The first thing I would do is pull the bowls off and either clean the jets or better still put new ones in as they aren't that expensive, but you should have some new bowl gaskets to hand when you do that, and maybe some fresh inlet rubbers. I'd also throw in some fresh spark plugs.

The fuel pump should pump a healthy amount (900mL/min) with the jumper connected; easy enough to direct it to a jug for a test. The fuel pump is a positive displacement type and will try and pump until the discharge flow is stopped. As Rogue says, it should click rapidly if it is starved of fuel or in need of priming (e.g. with the tap closed), and the clicking slows and then stops when the discharge side is closed e.g. by the float valves closing.

 

Engine not running it will only spit a few times unless it has constant 12v then it will pump continuously into an open container, as the manual states. You get x amount of cc's in x time

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Thanks for the tips guys, I will look again tomorrow, bedtime here now!
Cheers, Tony.