my bike cut out whilst I was riding recently, after fuel getting low, when it started spluttering I quickly turned fuel tap to reserve, but bike came to a stop, after calling breakdown they said it was fuel pump failure, anyway I now have cleaned points at the fuel pump and connected a 12 volt battery to it and it pumps well but when I try to start machine on the bike it turns over nicely but no fuel from pump outlet, also when I put a multimeter on live feed to pump it only shows about 8.5 volts on live wire, but a live feed just before the relay it shows 12.8V I cant see any breaks in wires, so does anyone know if it could br the fuel cutoff relay, I tried to look at relay but it is a sealed unit, and my knowledge of electrics is somewhat limiled, please does anyone out there have an idea of what I need to look at, Thanks Steve
Hi all I have a 1991 750 vfr and lately the bike has been cutting out when warm, I pinned it down to a hot and broken fuel cut off relay, so bought another one and the bike did it again this time i notice the fuel pump was red hot, so bought a new points set on pump rear bike ran for about 2-4 miles then cut out, pump hot again, the only thing I changed a few days before was a new fuel line from the tank down to the pump, and as I had to bend the pipe without kinking it i put a spring inside the line so that it formed a smooth curve, surely this cant be making the pump get hot, I would appreiciate anyones thoughts on this, thanks Steve
Hot, overworked pump suggests no (or insufficient) fuel is getting TO the pump, so suspect kinked line, plugged filter, anything that reduces flow.
Thanks for quick reply, you may be right , so I went out to try Fuel line without spring, and took it for short ride before feeling pump, pump wasn't quite so hot, but when I tried to restart bike it kept blowing the fuse that says fuel and ignition, I am not great on electrics but could this be a bad bit of wiring, Many thanks once again,
unplug the pump wiring, set your meter to an ohm setting and take the one probe and put it on one pin, the other probe goes to the other pin. then post the reading and ohm setting you had it on, ie 10k range
Honda VFR 750 FM RC36 91 Fuel Pump Repair Kit - Point Switch Parts at Wemoto - The UK's No.1 On-Line Motorcycle Parts Retailer this will help out with that pump, sounds like your points are welded
Thanks Right done that, set to ohms, had to set dial on 20k as meter went from 2 - 20k no 10, dont know if that makes difference but reading on 20k was 0.05 dont know if that is good or bad as my manual doesn't give fiqure for pump, by the way I have sourced a good second hand working relay and renewed a couple of bad connectors in the line and bike does start and run, but after 2 - 3 miles round the block the see through fuel filter starts to empty of fuel compltely, so I stop the bike before it pumps air, I dont know if this is related or not, and maybe you may not, but either way you have been a great help anyway, PS I think the bike would run sort of ok now as the pump is only getting just warm over a short distance, now I have renewed those joints, its just that I dont think the see through filter should loose the fuel in it down to nothing after a short while, I can tell you the all i did previously was renew the fuel line from tank to inline filter, and altough the original pipe that was pited had built in bends in it, the new straight pipe that I had to try and bend round in two places seems not to be too resricted, and I have tested the free flow from tank through new pipe and it pours out nicely, sorry to be pain and thanks either way Steve
I'm have a similar issue on my '93 RC-36. It rode 30 min. bogged out like no gas (with 1/2tank still). Started with choke but would bog on throttle open. I've found the pump likes to overheat and fail and work once its cooled down. Check filter for obstructions and also check venting from the tank. Pump should activate when cylinders 2&4 fire. I've read a lot about these pumps overheating, I think your concern should be with the resistance and connections in your relay circuit. (pump to harness to relay switch)
fuel pump should run on cylinders 2&4 firing. I would check continuity to fuel switch relay, and problem will most likely be closer to the relay than the pump. If you've already checked filter, tank, vent and line after pump for flow. I'm searching for solutions on my '93 rc-36 which bogged down last night like it was out of gas. So I towed it back and am about to get into checking those elements around the fuel pump, i'll post if I discover anything relevant.
Best to BYPASS the relay entirely and throw it into the bin. At the plug going to relay, use a wire to jump the 2 wires there so that voltage is sent to pump whenever key is on.........for testing purposes at least. Relays fail more often than pumps, so remove it from the circuitry. After defective voltage regulators and associated wiring, pump relays are the most common ( carbed) VFR electrickal gremlins........and they're actually unnecessary !
