Is the fuel pump relay actually necessary?

[Forcerouge]

I wonder if the fuel pump relay is actually mandatory?
I believe mine doesn't work and it is very hard to find a new one where I live.

I've noticed that once the relay shorted, the pump will work until the carbs are full, then it stops naturally by itself after it senses enough back pressure.
So basically it doesn't need a relay to get on and off automagically, it does that just by itself.

So I wonder, what is the actual purpose of this relay and can I just run the bike without it?

[ParcNHawk]

It's supposed to be a safety feature to prevent a crashed bike from dumping fuel out because the key is still on.

Many owners bypass it.

[Forcerouge]

Ah yeah, that makes sense, thank you!
I'll go for no safety then, and try to find a new relay in the meantime

Thanks again for your help !

[squirrelman]

after the first time that bloody relay left me stranded, i've bypAssed it on every honda i've owed........and i ain't boined up yet so far.

[bk94si]

I had mine bypassed and got into an accident. Gas spilled all over the ground but it wasn't really a problem. I have a vacuum pump now so it no longer matters anymore.

[Forcerouge]

I have a vacuum pump now so it no longer matters anymore.

Seems interesting, could you tell me more about it or point me to a thread?
I've got very limited confidence in my pump, it already broke once and I had to repair it with the remains of another pump, so I can't say I'm very confident for it to run for long...

[bk94si]

Hordpower.com

[6]

lots of these guys love the vacuum pump mod. Its not for me.... I bypass the relay and thats that. There are a multitude of electric fuel pumps that can work,


That said WW maked a dope mount for the vacuum pump, and jd sells the pumps, and there is a lot of knowledge about the system on here as its a well walked path. So you cant go too wrong with it

[bitzz]

There is nothing "special" about that relay.
Run down to your local electronic supply and pick up a 6 or 10 amp 12v relay and wire it up to the Honda plug.
Simple, costs about $2

A Mikuni pump will work, but the pump doesn't pump till the motor starts.
The OEM Honda pump is also nothing special, and not terribly robust. I have a Holley pump that has been faultless for years and years and years. If you use an aftermarket pump be aware they come in different "sizes" or pressures. You WANT about 6 or 7 PSI, the needle valve will leak at 10 PSI.

[Forcerouge]

Lots of useful info, thanks.
I can't buy the stuff you guys recommend since I'm not in the USA, but I'll check for similar stuff here when my pump breaks

[squirrelman]

There is nothing "special" about that relay.
Run down to your local electronic supply and pick up a 6 or 10 amp 12v relay and wire it up to the Honda plug.
Simple, costs about $2

A Mikuni pump will work, but the pump doesn't pump till the motor starts.
The OEM Honda pump is also nothing special, and not terribly robust. I have a Holley pump that has been faultless for years and years and years. If you use an aftermarket pump be aware they come in different "sizes" or pressures. You WANT about 6 or 7 PSI, the needle valve will leak at 10 PSI.

oem pumps @ 3psi.

[flyinelvis]

When the fuel pump died on my CB-1, I replaced it with a Facet 40171 electronic pump. These are utilized in small engine aircraft, and if they can keep a plane aloft, they can certainly keep a Hawk on the road. Of course mounting said pump would take some effort, but they work like a charm on the CB-1’s, so may be applicable here.

I have utilize the Mikuni mechanical pump since I first built my bike. It’s been bulletproof, but keep in mind there will be some cranking involved to fill the bowls as it is a vacuum system, whereas the OEM pump is pretty much instantaneous with fuel flow…

[rpcraft]

There is nothing "special" about that relay.
Run down to your local electronic supply and pick up a 6 or 10 amp 12v relay and wire it up to the Honda plug.
Simple, costs about $2

A Mikuni pump will work, but the pump doesn't pump till the motor starts.
The OEM Honda pump is also nothing special, and not terribly robust. I have a Holley pump that has been faultless for years and years and years. If you use an aftermarket pump be aware they come in different "sizes" or pressures. You WANT about 6 or 7 PSI, the needle valve will leak at 10 PSI.

FYI, The vacuum pumps will pull as long as you can crank the motor and it has enough compression to run. It doesn't have to actually be running.

[rpcraft]

oem pumps @ 3psi.

Hey Jerry do you (or does anyone) happen you know what the flow rate is on the stock pump? I'm just curious. I figure given the story that the fuel pump was really just included to empty the tank I doubt it has to be very much.

[Captain 80s]

Hey Jerry do you (or does anyone) happen you know what the flow rate is on the stock pump? I'm just curious. I figure given the story that the fuel pump was really just included to empty the tank I doubt it has to be very much.

From the FSM:

Turn the ignition switch ON and let fuel flow into the beaker
for 5 seconds, then turn the ignition switch OFF.
Multiply the amount in the beaker by 12 to determine the fuel
pump flow capacity per minute.

FUEL PUMP FLOW CAPACITY:
600 cc (0.630 US qt 0.528 Imp qt)/minute at 10 V