Honda Shadow Forums banner

1 - 20 of 24 Posts

·
Registered
Joined
·
2,806 Posts
Discussion Starter #1
If you have a Honda with a fuel pump relay, you probably know that the relay only energizes the fuel pump when the motor cranks. This can leave you stranded if the relay goes bad or you run out of fuel. Cranking the engine to fill empty carbs can drain your battery dead before the carbs fill. The options are to bridge the relay with a jumper or wire in a switch. Be sure to use a switch that will stand a minimum of 5 amps. I bought a Radio Shack 25 Amp 12V rocker to wire in.

Here is the relay.


This is how you bridge the connector with a jumper wire.
Black wire and Black w/Blue stripe wire on my '83.


New wiring soldered into the relay wires.


Insulated connectors crimped onto the wires.
Soldered joints taped up. Switch connected.


The switch sits neatly inside the side panel without needing a bracket.
If the switch gets bumped, the worst that could happen is that the pump would work when the key is turned on.
(Radio Shack supplied a bracket, but I elected not to use it. You might want to.)
 

·
Registered
Joined
·
3,761 Posts
I did the same thing, except I used a momentary contact switch for mine.

The probability of it ever happening is slim, especially where yours is,
but I used a momentary contact just in case a toggle could get switched
during an accident.
 

·
Registered
Joined
·
221 Posts
litnin said:
I did the same thing, except I used a momentary contact switch for mine.

The probability of it ever happening is slim, especially where yours is,
but I used a momentary contact just in case a toggle could get switched
during an accident.
So do you hold in the momentary toggle while you ride it home? I ask because as soon as you release it the fuel pump would quit and I didn't think gravity would work.
 

·
Registered
Joined
·
1,718 Posts
gelsbern said:
litnin said:
I did the same thing, except I used a momentary contact switch for mine.

The probability of it ever happening is slim, especially where yours is,
but I used a momentary contact just in case a toggle could get switched
during an accident.
So do you hold in the momentary toggle while you ride it home? I ask because as soon as you release it the fuel pump would quit and I didn't think gravity would work.
No! the switch is to bypass the ignition signal that makes the pump run normally. The switch is incase you run your carbs dry (run out of gas) you can turn on the switch long enough to PRIME the carburetors. So the switch is a way to install a priming circuit, once the carbs are full and the bike is running the priming circuit is to be switched off.
MarkC
 

·
Registered
Joined
·
2,806 Posts
Discussion Starter #6
In addition to what Mark said, it is also useful if you lose the relay on the road. The fuel pump will only run till the carbs are full, and it will keep them full.
 

·
Registered
Joined
·
339 Posts
I added bypass switches that activate the relay for the pump on our 1100s, so 5 amp contacts are not really a necessity. However, going this route also means that if the fuel pump relay died on you (As in the previous post stated), you wont be able to run the pump. It will help you diagnose the problem of a bad relay though!

Works like a charm to pump the bowls full after draining or if you run out of gas and need to fill the bowls again. :)

Mark
 

·
Registered
Joined
·
2,806 Posts
Discussion Starter #8
Mark, I'm wired in beyond the relay. I can turn the switch on and run the pump w/o the relay.

zikzak said:
I added bypass switches that activate the relay for the pump on our 1100s
Mark
 

·
Registered
Joined
·
1 Posts
Relay bridge = Lifesaver

Just got my hands on my brothers old Shadow VT750 1984.
It didn't start unless I used a charger/boost making it impossible to use the bike for commuting or errands...

Bridging the relay fixed it!
Thanks!
 

·
Registered
Joined
·
2,806 Posts
Discussion Starter #10
drflex, I'm glad that bridging the relay got your bike going. Since you mentioned needing additional power, I suspect that you have work to do in the charging system and battery. The bridge merely eliminates the relay.
If you need a manual, here is a download.
http://www.carlsalter.com/download.asp?fileid=072111110100097095086084055048048099045086084055053048099095039056052095115104111112095109097110117097108046112100102
For electrical diagnosis, I recommend this trouble shooting chart.
http://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-finding-diagram.pdf
There a couple of great guys (and gals), on this list that are very good with early 80's Shadows. Post a new thread on the technical area mentioning the 84 vt750 and some indication of your problem. I have a 83 vt750c, but won't be available to help much in the near future.
Good luck
 

·
Registered
Joined
·
11 Posts
will it cause any damage if I keep it like this? my relay went out and I havent found the replacement for it.. I just did this solution but I dont know how long the fuel pump will last connected like this...
 

·
Premium Member
Joined
·
1,138 Posts
Forever, the fuel pump will not be harmed.

If you crash though the pump will run until the ignition switch is off. I use a standard relay that is switched from the kill switch, so I can kill the engine and the fuel flow, even if the ignition switch is under the bike.

Sent from my NookColor using Motorcycle.com App
 

·
Registered
Joined
·
76 Posts
relay trouble

so we plug the switch on/off to replace the relay and if I run out of gas
I put the switch on until my carb are full and put back the switch off?

when the switch(the one that replace the relay) is off is the fuel pump will work when I put my ignition on EVEN IF MY CARB ARE FULL,
Thanks
 

·
Registered
Joined
·
1,529 Posts
LOL genius!

I dont know how many Times I have killed my battery cranking to refill with fuel after working on my bike then either had to jump it or wait for it to charge up. LOL totally going to install one of these at some point in the future.
 

·
Registered
Joined
·
76 Posts
I have cleaned the carbur ok now I have jumped the relay do I leave the jumper
on it all a time,wait to start the bike until have a answer,please reply so I can ride
my bike,thanks
 

·
Registered
Joined
·
2,257 Posts
I have cleaned the carbur ok now I have jumped the relay do I leave the jumper
on it all a time,wait to start the bike until have a answer,please reply so I can ride
my bike,thanks
Plug the relay in, and start the bike.
If the relay is working fine, you do not need to leave the jumper in the on position.
If you do not have a relay of if it is no good, you need to leave it connectoed.
It is only there to prime the Carbs if they are emty, or for relay failure.
 

·
Registered
Joined
·
23 Posts
99 Honda Shadow Aero 1100 Fuel Pump Relay circuit diagram
My 99 honda showow aero 1100 fuel pump relay went bad. I tried to fix it by opening the relay but looks like the fuel pump relay is molted with cement so no way to open it. Please let me know were can I get the detail circuit diagram of the fuel pump relay so that I can build from scratch.

Anyone build the fuel pump relay from scratch yet?

Any help would be great.

Thx
Sppa:lol:
 
1 - 20 of 24 Posts
Top