Honda VT700C fuel shut off relay

The fuel pump only works on my 1985 VT700C if I connect it directly to the
battery. It appears that the fuel shut off relay (tip over switch) is
defective. How can I test the relay? An ohm meter shows that all (3)
contacts are open no matter what the orientation the switch. I believe the
correct orientation is standing tall with the contacts at the bottom. What
is the third contact on the relay for? My wiring diagram shows it going to
the ignition unit.

Thanks,

KH

 

You made refference to the thrid contact in the relay, that lead should
be the one coming from the Ignition switch, and it should have voltage
when the key is on. One of the other leads should be going to the fuel
pump and with the key in the on postion, it will show battery voltage.
The last lead should have batter voltage all the time even with the key
in the off postion. If you do not have battery voltage going to the fuel
pump off that lead and yet the other two have voltage with the key
switch on, then yes you do have a problem within the relay as far as the
tip over switch with in the relay.

Hope that helps you out.

David

 

Thank you for responding to my question.

My problem appears to be a bad batch of fuel. The simptoms were fuel
starvation the day after I filled the tank and drove 30 miles. Draining the
fuel system and filling with fresh fuel has reduced the problem. Another
fill should eliminate it. However, during my trouble shooting activities I
got interested in the fuel cut switch. I have two of these units now and
they both behave the same way. Testing with an ohm meter shows that there
is no connection between any of the contacts in any orientation. When the
unit is installed, I measure the following voltages. There are no voltages
on any of the leads with the key off. The fuel pump gives one click when I
turn on the key. 0 volts on the lead to the pump and 12+ volts on the other
two leads. When I start the engine, approximately 4 volts appears on the
pump lead. I read somewhere that the fuel pump will not run when there is
no oil pressure. The voltages do not seem effected by the orientation of
the switch. Interesting behavior for a tip over switch Any more thoughts
on what is going on?

KH

 

Hey again,

After reading what you had wrote, I can only come up with a couple
ideas, you stated that you had 0 volts to the fuel pump lead off the
relay, and then you stated that after starting it you had 4 volts at the
fuel pump, I am assuming you that was not with the relay in the circuit
at all when you had the 4 volts? If your going to check voltage supply
to your fuel pump, you have to disconnect the lead going to the pump to
get the amount of voltage, because if your fuel pump has an internal
short no matter how small the voltage reading will drop drastically, so
check it with the lead off the fuel pump. If it shows battery voltage
approx 12V with the lead off and 4V with the lead on, you most
definitely have a fuel pump problem. but if there is no voltage going to
the fuel while key on and maybe also trying to start the machine as
well, I was looking at a wiring diagram and the one wire comes from an
ignition module which might need to sense that the engine is cranking
for the fuel pump to operate.

So to recap here, check voltage at the fuel pump with it disconnected
from the fuel pump,and as well with it connected. if it is both 0 volts
then replace the relay, if it is battery voltage with it disconnected
and 4 volts with it connected, then I would replace the fuel pump.
BUT REMEMBER TO CRANK THE ENGINE OVER WHEN CHECKING THE VOLTAGE GOING TO
THE FUEL PUMP!

I looked for a wiring diagram for your bike, I found one but the years
and model were not exactly right on but I thought it might be close, and
it even had the wire colors so as you could compare yours to the diagram.

Here is the link

http://www.smokeriders.com/diagrams/index.php?show=Honda/98-00_VT750C_CD_ACE.gif

Here is the page for a list of other models and other makes of bikes to
look though.

http://smokeriders.com/Technical/wiring_diagrams/wiring_diagrams.html

I hope that is of some more help for you,

David

 

Hey again,

After reading what you had wrote, I can only come up with a couple
ideas, you stated that you had 0 volts to the fuel pump lead off the
relay, and then you stated that after starting it you had 4 volts at the
fuel pump, I am assuming you that was not with the relay in the circuit
at all you had the 4 volts? If your going to check voltage supply to
your fuel pump, you have to disconnect the lead going to the pump to get
the amount of voltage, because if your fuel pump has an internal short
no matter how small the voltage reading will drop drastically, so check
it with the lead off the fuel pump. If it shows battery voltage approx
12V with the lead off and 4V with the lead on, you most deffinetly have
a fuel pump problem. but if there is no voltage going to the fuel while
key on and maybe also trying to start the machine as well, I was looking
at a wiring diagram and the one wire comes from an ignition module which
might need to sense that the engine is cranking for the fuel pump to
operate.

So to recap here, check voltage at the fuel pump with it disconneted
from the fuel pump,and as well with it connected. if it is both 0 volts
then replace the relay, if it is battery voltage with it disconnected
and 4 volts with it connected, then I would replace the fuel pump.
BUT REMEMBER TO CRANK THE ENGINE OVER WHEN CHECKING THE VOLTAGE GOING TO
THE FUEL PUMP!

I looked for a wiring diagram for your bike, I found one but the years
and model were not exactly right on but I thought it might be close, and
it even had the wire colors so as you could compare yours to the diagram.

Here is the link

http://www.smokeriders.com/diagrams/index.php?show=Honda/98-00_VT750C_CD_ACE.gif

Here is the page for a list of other models and other makes of bikes to
look though.

http://smokeriders.com/Technical/wiring_diagrams/wiring_diagrams.html

I hope that is of some more help for you,

David