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Fuel Pump on a 1987 VFR 700?


Ziffer

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So, I bought this 1987 VFR 700. The weather has cleared up momentarily here, so I started working on it. On closer inspection, the electrical system looks like a rats nest, and it appears a 12 year old meth addict has worked on it before me. You know, the childish practices of replacing color coded wire with random speaker wire; twisting bare wires together, putting tape over it, and calling it good; losing screws, and just putting whatever is handy in it's place, etc.

 

In spite of that, using a wiring diagram I sourced from VFRD, I have been able to get it to run. But that has brought up a question. I see where the diagram refers to a fuel pump. And that reminded me that the PO mentioned something about the fuel pump not working. Does this bike have a fuel pump? If so, why? All the carbureted bikes I have worked on were gravity fed.

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Yes they have a pump.    Likely to ensure that at low fuel levels, flow is still safely adequate.  One of the few V4s they ditched the pump on was the 86 VF500F after two years of having a pump.  But they completely changed how the fuel flowed to the carbs.  The petcock was right above the carbs with a splitter feeding two carb inlets.

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Definitely needs fuel-pump. Won't be able to use more than 1/3-1/2 of tank without pump. Problem is most idiot mechanics don't realize that pump ONLY runs when engine is spinning. Turn key ON, no pump action, that's perfectly normal. But then they do all sorts of contortions and gimmicks to force pump to run and end up butchering wiring and bike in process.

 

Ingenious design of this system is fuel-pump relay. It's not just on/off with power like headlight relay. Fuel-pump relay ONLY turns on pump for fraction of second when there's ignition pulse. At low-RPMs and idle, there's few pulses per second and small amount of petrol is sent to carbs. At higher-RPMs, there's more ignition-pulses per second and more fuel is pumped to carbs to meet demands of higher loads. Amazing!! 

 

Also if you look inside tank, pick-up for petcock is higher than bottom of tank. That's about 5-ltr that can not get out of tank without pump.

 

Don't buy crappy aftermarket pump. OEM Mitsubishi pump is good. Quantum and Kemso are decent aftermarket pumps

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Best of both worlds...  Wire in a parallel toggle.  Prime the system after storage or sitting for a while.  Also gets your ass home when the relay fails.  (Twice now, one in the middle of a floating bridge)

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So, where is this mythical pump located? In the tank? On the frame? Actually, there are a lot of parts missing off this bike, so I'm thinking the PO, when he said it needs a fuel pump, he meant it was missing altogether. But so far, I can't even find the pump connector.

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6 minutes ago, Captain 80s said:

Best of both worlds...  Wire in a parallel toggle.  Prime the system after storage or sitting for a while.  Also gets your ass home when the relay fails.  (Twice now, one in the middle of a floating bridge)

Great idea!

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7 minutes ago, Ziffer said:

So, where is this mythical pump located? In the tank? On the frame? Actually, there are a lot of parts missing off this bike, so I'm thinking the PO, when he said it needs a fuel pump, he meant it was missing altogether. But so far, I can't even find the pump connector.

It should be right under your bum.37D7F3D6-5A70-488B-9FC7-0D981A96C2BE.thumb.jpeg.c1a923ce2617733795bafacbb192c116.jpeg

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33 minutes ago, DannoXYZ said:

It should be right under your bum.37D7F3D6-5A70-488B-9FC7-0D981A96C2BE.thumb.jpeg.c1a923ce2617733795bafacbb192c116.jpeg

 

Thanks! That pic was quite helpful. Now the fuel lines make more sense. So, my pump is missing, along with the bracketry...and the coolant overflow tank...and whatever that line is going under the coolant reservoir. :mellow:

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Is there a wiring diagram for the 1987 VFR? I've been using one for a 1986, but I'm seeing that my electrical issues are worse than I had hoped. So, I think I need accurate, reliable data.

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It's gonna be pretty much the same for the stuff your are dealing with.  It is different when you get into the actual ignition system (no cam sensor on the 87) and maybe a little with the dash (tach maybe).

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35 minutes ago, Ziffer said:

 

and whatever that line is going under the coolant reservoir

 

That "line" is the 3 yellow wires from the stator to the reg/rect.

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2 hours ago, Ziffer said:

Is there a wiring diagram for the 1987 VFR? I've been using one for a 1986, but I'm seeing that my electrical issues are worse than I had hoped. So, I think I need accurate, reliable data.

It's same as '86. Just remove cam-sensor and it's same

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3 hours ago, Captain 80s said:

It's gonna be pretty much the same for the stuff your are dealing with.  It is different when you get into the actual ignition system (no cam sensor on the 87) and maybe a little with the dash (tach maybe).

 

1 hour ago, DannoXYZ said:

It's same as '86. Just remove cam-sensor and it's same

 

Ok, so, wire colors are the same? That's what I'm after right now.

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3 hours ago, Captain 80s said:

 

That "line" is the 3 yellow wires from the stator to the reg/rect.

Gotcha. Mine has been "rerouted." And the wires coming out of the alternator (magneto?) are black.

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Might be some aftermarket replacement, mine's yellow too.

 

After 37-yrs, my RC24's RR failed. It had the PC-fan mod on it, very cute! But, I think 110F Phoenix rides finally did it in. Borrowed from VFR700 while I assemble modern series-circuit SH775 and harness together...

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13 hours ago, Ziffer said:

 

 

Ok, so, wire colors are the same? That's what I'm after right now.

Yup, exactly same. I've got both '86 VFR750 and '87 VFR700. Have used same diagram on both without any issues.

 

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And for my next question...

I'm considering buying a junkyard wire harness. I've seen a few on eBay for a 1987 VFR 700/750. I've never bought a junkyard wire harness. Is it worth doing? Or do you just get a bunch of broken connectors and brittle wires?

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When you find some that look promising, go to "See other items" and put in the same key words regarding the bike.  Then look at what else is for sale.  Does it look like it used to be an anchor?  Is the dash listed with 120,000 miles?  Is everything sun faded beyond recognition?  Keep doing that until the rest of the bike appears be decent and it increases your chances of getting good used parts.  Pay attention to how the other stuff appears to be disassembled and displayed.  Are they hacks, or do they present parts properly with a high satisfaction rating? Also RETURN POLICY.  The cost of return shipping is pretty low.  I employ that method on many things, and my success rate on getting good deals on good stuff is very high.  The few times I've received some bad parts, I documented what was wrong and politely stated why it's bad and they didn't even want me to return it, just refunded me.

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1 hour ago, Captain 80s said:

When you find some that look promising, go to "See other items" and put in the same key words regarding the bike.  Then look at what else is for sale.  Does it look like it used to be an anchor?  Is the dash listed with 120,000 miles?  Is everything sun faded beyond recognition?  Keep doing that until the rest of the bike appears be decent and it increases your chances of getting good used parts.  Pay attention to how the other stuff appears to be disassembled and displayed.  Are they hacks, or do they present parts properly with a high satisfaction rating? Also RETURN POLICY.  The cost of return shipping is pretty low.  I employ that method on many things, and my success rate on getting good deals on good stuff is very high.  The few times I've received some bad parts, I documented what was wrong and politely stated why it's bad and they didn't even want me to return it, just refunded me.

Sounds like good advice.

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Just to give you an idea of what I'm working with, this is after I've removed a bunch of fabricy, gooey tape:

 

IMG_20230323_162357[1].jpg

IMG_20230323_162407[1].jpg

IMG_20230323_162559[1].jpg

IMG_20230323_163936[1].jpg

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Start THE-FUCK over with a used one.  Literally anything is better than that rat's nest.

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10 minutes ago, Captain 80s said:

Start THE-FUCK over with a used one.  Literally anything is better than that rat's nest.

 

LOL! Yeah, I've been starting to lean that way.

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Ok, so, it's the 1986 that has the cam sensor (pulser?)? Not the 1987? So, a 1986 harness should work fine on a 1987. Right?

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