'87 VT1100 fuel pump question - Honda Shadow Forums : Shadow Motorcycle Forum

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Old 02-05-2008, 05:40 PM   #1 (permalink)
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Default '87 VT1100 fuel pump question

This 1100 Shadow is the first motorcycle I've owned or worked on with a fuel pump. All the others, and there have been many, have been gravity feed only. I have a question I hope someone can answer.

How do you test a fuel pump to see if it is working correctly? This bike sat for a long time before I got it. The previous owner told me he had tested the fuel pump and it was good. But it isn't pumping any fuel.

Details: I have replaced the petcock, and the fuel lines to and from the fuel pump were replaced by the PO. I have confirmed that gas is making it through the fuel filter to the fuel pump. I pulled the line that runs to the carbs and nothing is coming out of it. I tried to prime the pump by pouring gas into that line, but it didn't help.

The fuel pump apparently has power going to it, but the wiring in the bike has been messed with. There are three wires and a ground coming out of the harness that connects to the fuel pump. Only two of those wires are connected to live wires. I'm not sure how to check the ground. The third wire, a black and yellow one, has no corresponding wire coming out of the other side of the connector. The wiring diagram in my Clymer manual shows only two wires and a ground running to the fuel pump. Both of the wires matching the colors in the wiring diagram are connected to live wires.

One thing I have considered, but haven't done because I wasn't ready yet to disassemble bike, was the possibility that the fuel lines into and out of the fuel pump have been switched. Can anyone tell me which is the fuel in connector and which one is the fuel out connector on the pump?

Before I spend a lot of money I don't really have to buy a new fuel pump I'd like to be able to find out for sure if this one is good or bad.

Any suggestions, anyone?

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
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Old 02-05-2008, 07:06 PM   #2 (permalink)
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Here is how you do a fuel pump test for a 1997+ Shadow 1100 not sure how much it relates to your bike. The pump runs off the coil power not ignition on so you won't see any delivery until it's started.

Directions for Fuel Delivery Test from Service Manual below:

The directions for a 97-2003 VT1100
Turn Ignition off
Disconnect the fuel cut--off relay connector (under the seat)
Check for battery voltage between the Black (+) terminal and ground. (-)
There should be battery voltage with the ignition switch ON
If there is no voltage, check for open circuit or loose connections in Black wire.

Check for continuity between the Black/Blue and ground, If there is continuity, faulty fuel cut-off relay.

If there is no continuity, short the Black and Black/Blue terminals at the relay connector with a suitable jumber wire.
Disconnect the fuel pump 2P (black) connector and check for battery voltage between the black/blue (+) and green (-) terminals with the ignition switch ON.
If there is battery voltage, faulty fuel pump.
If there is no battery voltage, check for open circuit or losse connection in the Black/Blue and greeen wires.

Discharge Volume inspection
Short the Black and Black/blue terminals with a suitable jumper wire.
Hold a beaker under the fuel line that goes to the carbs and turn on ignition. wait 5 seconds should come out to about 28oz a minute.
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Old 02-05-2008, 07:11 PM   #3 (permalink)
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Thanks, Chuck. I'll go look at it again.

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
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Old 02-05-2008, 08:55 PM   #4 (permalink)
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i have a factory 1987 manual for the vt1100 if you need a wiring diagram
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Old 02-05-2008, 09:10 PM   #5 (permalink)
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That would be really cool, Fixer. From experience I know Clymer wiring diagrams cannot necessarily be trusted. The Clymer for my 1969 Honda CB750, for example, does not acknowledge that my bike has front blinkers....

Could you email it to me?

Thanks,

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
1969 Yamaha DT1
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Old 02-06-2008, 12:39 AM   #6 (permalink)
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A question - this fuel pump should pump fuel with the key on only, right? The bike doesn't have to be cranking or running, does it?

Thanks in advance for any insight you can offer.

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
1969 Yamaha DT1
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Old 02-06-2008, 01:41 AM   #7 (permalink)
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When you first turn on the key, you may hear the fuel pump click once and pump one stroke. After that, the fuel pump relay needs a signal from the ignition.

Some people bypass the relay when the relay goes bad, but that is bypassing a safety feature also.

For testing, you can run a hot wire directly to the pump.
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Old 02-06-2008, 11:04 AM   #8 (permalink)
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It's that signal from the ignition that has me wondering now, Callmeal. I emailed the previous owner and he told me the relay is bad so he rewired the pump. I pulled off the electrical tape last night and this is what I found:

The blue and yellow hot wire from the spark unit is now wired directly to the black hot lead from the fuel pump and a black and yellow wire from the fuel pump. The black and yellow wire does not appear on my Clymer wiring diagram. I don't know what it does, or what it should be connected to. The is no black and yellow wire at the connector the fuel pump connects to. The end of the blue and yellow wire to the sparker that comes from the fuel pump is not connected to anything right now.

The PO said this wiring scheme allows the fuel pump to be turned on and off with the kill switch. If that is so, and the fuel pump is waiting for a signal from the ignition, do I need to turn the kill switch off and then on again to tell the pump to start working?

Does anyone know what the third wire, the black and yellow one, does? Does the signal from the ignition need to come from the sparker? Do I need to reconnect the blue and yellow wire from the fuel pump to a hot wire?

I am slowly starting to get some grasp of this. Abraham Lincoln once said that learning for him was like pounding letters into iron. It took a long time to get it done, but once it was in it stayed forever. I'm kinda like that.

Thanks,

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
1969 Yamaha DT1
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Old 02-06-2008, 02:10 PM   #9 (permalink)
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OK, at Callmeal's suggestion I ran a hot wire directly from the battery to the fuel pump and it immediately began chugging away reassuringly. So the pump is good, but the relay is bad. What is the correct way to wire around the relay so that the fuel pump will work without a wire directly from the battery. The PO used a wire off the hot wire from the sparker, thinking this would allow the kill switch to serve as an "off" switch, but the pump doesn't run this way. Could it be that so far unidentified wire from the fuel pump, the black and yellow one, that is causing the pump not to run? Or does the pump require the amperage supplied by two hot wires - the black and the blue and yellow - to have enough juice to run.

I'm almost there, with a little more help I can see if this beast runs....

Thanks,

Patrick
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1987 Honda Shadow VT1100
1969 Honda CB750
1975 Honda CB750K
1978 Honda CB750F3
1979 Yamaha XS11
1969 Yamaha DT1
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Old 02-06-2008, 08:14 PM   #10 (permalink)
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post your email address and i will scan the wire dia and send it to you asap.
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