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1983 Honda vt750 Shadow
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I think it can be done since it is the same idea that was used for several years already, 1983-85.
Same system on yours with fewer parts I guess.
 

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Discussion Starter · #22 ·
I think it can be done since it is the same idea that was used for several years already, 1983-85.
Same system on yours with fewer parts I guess.
Thanks Swifty, yes, I got the picture you send... but the relay? what would be the specs? or are all the same?
I research some and there are several relays from Honda XVR 750 Africa, Shadow VLX 600, Magna and those kinds (that I can get here in the worlds ass)
Like this (thats the only photo I could get from the seller, will have to see if it has 3 contacts and what is each...)


296763
 

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That looks a lot like the one in our ‘83s. Granted, mine exploded, but I am confident you will have better results, and your Mom doesn’t have to get involved! Trying to find a regular relay would have been a challenge. I’m sure you’d have to have found one that wouldn’t blindly open/close with the pulses, but would stay in either state depending on how the pulses were delivered…
 

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Discussion Starter · #25 · (Edited)
They are an electronic relay-transistor controlled, so it has to be the same, not a standard contact relay.
Yes 3 pins to match the diagram above. That one in the picture looks like mine.
Look down on the list of models here, it shows 82 models it will fit.

Hello hello, I am back... (damn :p sorry)

I could make it run (thanks for all the help from here) 🙏 🤟

Some other problems showed up, that could not yet figure out but to resume, can say:

1) Quantum Fuel Pump is (in my luck) a bad choice, it blew its cirquit on just a few miles.

2) I could run the QFP with out the cirquit connecting directly like:

These are the QFP cable specs I use:
1) Yellow\green=ground
2) Red=Positive (I add here a diode, also, checking the polarity, just in case, stealing some of your knowledge you:geek:, hope I learnt it good)

These are VT700c 86 cable specs:
1) GREEN = Ground
2) BLACK = +12 VOLTS
0) YELLOW/BLACK = Not hooked up to anything.
3) BLUE = Pulse signal wire from the Spark Unit.

Next will try to get a new Honda original pump, I read somewhere in here, there is a Honda Civic compatible one, that hope fits the small place where it must be installed. Will add the external relay, too.

And will check the wire harness wiring from the pump to the pulse unit, I want to be sure its fine... cant belive the QFP cirquit burnt out for nothing.

Thanks🖖
 

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Discussion Starter · #26 ·
Just arrived the relay! now I need to get the right connectors to adapt my installation next days.

One more thing to add/ask to the previous post, is it possible that if the quantum fuel pump (the one I had to take out the cirquit because it burned), its not supposed to run without the cirquit? I also read in the forum that when it is connected directly it might present a synthom that when you turn the key to ON, it will not just start pumping always depending on how it stopped before?
I mean suppose the pump does continuously open/close, open/close, open/close,etc. But when you turn off the bike the open/close loop ends in "open" so then when you turn it ON again it wont pump (until you ON/OFF again)

I think I notice this behaviour on my bike now (will see what happens with the relay connected)

Thanks,

Font Material property Rectangle Electronic device Technology


(I am kind of proud :) this company called Pietcard is from Argentina and they make these relays, also the voltage regulator and the pulse unit (CDI) for several vintage bikes, hope it helps for someone else and for sure the price here will be for worlds currency like buying candies!:LOL::cry:)
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Excellent learning of Pietcard.
As our bikes get older it is good to hear of alternate sources of parts, the Internet sure has made the world smaller, parts more findable and potential customers more numerous for manufacturers making production worthwhile.
 

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Discussion Starter · #28 ·
The 1983-85 uses a relay outside the pump. But It looks like the 1986-87 shows a circuit inside the pump body.
But I can't offer any advice about it. Unless you go to the the earlier system wiring.
Swifty... I am trying to use the earlier system wiring 84 (right picture like yours) with my 86 system wiring (left picture like mine), here I follow the lines and "seems" it can be adapted.
(I am asking because I did the test connecting as I thought it was but the "ignition fuse" burned :) damn)

This is how I connected the relay between the pump and the bike wiring, do you think it is right? (the fuse also could have been little weak and burnt just because of old, but I dont want to test again until being more sure I am doing it right)

Thanks again for the help and patience!

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VT 700 1986
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VT 700 1984/1985
Rectangle Schematic Font Line Parallel



Rectangle Product Schematic Font Engineering
 

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Not sure looking at your relay which terminal is which. But I understand this diagram better. See if it matches.
Here is a picture of my 1983 750 also.
 

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Discussion Starter · #30 ·
Not sure looking at your relay which terminal is which. But I understand this diagram better. See if it matches.
Here is a picture of my 1983 750 also.
Thanks Swifty, I made the connections my relay has the same connector specs. From your picture the first cable of the relay is Black/Blue, that one should send 12v to the pump.
The middle one Black, gets the 12v from regulator. And the third Blue wire, gets the ingnition pulses signal.

So I first tested the voltage out of the relay, I left the pump unconnected and test the Black/Blue wire, when ignition key on I get 12v. That sounds right?

OK, I connect the pump, turn ignition on and run switch on, the wire that comes from the pump 12+ started to get really hot without making the pump run, I turn ignition off after about 15sec when I heard burning electric noise and started smell (surely it was not a fart this time). Also checked the ignition fuse and It did not get burnt but I think little more seconds would be worse.

I can tell that this pump has 2 cables, ground and 12v. There is a diode just before going in the pump case throu the 12v cable. Well this diode is the one getting burn... maybe it is the wrong capacity?

Next thing would be testing without this diode, I understood the diode is a protection from conecting wrong polarity :unsure: so it is not a need if it is connected right (and also having the relay)

What do you think? 🤯

Thanks,
 

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Make sure the power is going the right direction to the pump wires and the diode. The white stripe on the end of the diode is the negative end toward ground. So make sure the power goes into the black end with no stripe.
 
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Hmmm… Now when mine exploded, it was because the pump I was using had started exhibiting odd signs. So pretty sure it just shorted and overloaded the relay. If you run the pump off of direct power, maybe try to put a fuse inline or measure with a meter to see how much current is being drawn?
 

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Discussion Starter · #34 ·
After all this time and work it may be best to try to get the original type 4 wire pump.
Sorry to say that.
Maybe available here #3 =

Yes, that was the first first thing I tried. The link you sent is out of stock (as all shops I search, there is no original pump anywhere), the only one I could get was this one QFS Electric Fuel Pump for Honda VT700C Carbureted 1986-1987, Replaces 16710-MK7-000

I got that one about 1 year ago, the connector was different just to start. So had to ask for cable specs (seems the add it now to their shop webpage), they send it to me, installed it and run about 15 kilometers and burn the cirquit it came with (I post that in this thread) also its circuit quality is really trash, chinese thin circuit tracks and low quality components (nothing to compare with the original).

So now I only have the pump now, without the circuit, just the 2 cables ground and 12+, that I wanted to adapt to the original relay as the old 84 wire specs.

I am now going to test the ampers it consumes, as suggested by Troy, because the pump itself may be shorted. If it is so, I can get a new one also 2 cables and adapting the relay hopefully will run thanks to all the help I got here.
 

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Discussion Starter · #35 ·
After all this time and work it may be best to try to get the original type 4 wire pump.
Sorry to say that.
Maybe available here #3 =

Hmmm… Now when mine exploded, it was because the pump I was using had started exhibiting odd signs. So pretty sure it just shorted and overloaded the relay. If you run the pump off of direct power, maybe try to put a fuse inline or measure with a meter to see how much current is being drawn?
I measured with the meter just now. I get 1.35amps buuuut... sometimes there are peaks of higher.
If the preassure is meet, the pump stops and amps goes cero (that should be right)
If the close a little the valve (I added a valve out the pump to cut the flow) the amps it consumes goes down (and the pumping too)
Also I notice that I have to turn ignition on and off some times to get the pump start continuously (seems it stops for some reason that is not the preasure)

Then the fuse blew out!...

This is the behaviour when the pump is shorted? can it be?
 

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1.3 amps is not much. Is it blowing a 10 amp fuse in the fuse box?
That same black wire goes to the regulator. Maybe unplug the regulator and repeat your testing. That may show something is drawing too much in the reg.
Is there any add on equipment connected otherwise?
 

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Discussion Starter · #37 ·
1.3 amps is not much. Is it blowing a 10 amp fuse in the fuse box?
That same black wire goes to the regulator. Maybe unplug the regulator and repeat your testing. That may show something is drawing too much in the reg.
Is there any add on equipment connected otherwise?
(yes it blew the 10amp fuse)

MMmm damn, I took out the pump... re-tested the consumption amps and it gives about 7,8 amps and no pumping sound (just one sound like when it opens the valve,each time I connect to voltage but no continious running)

This rings any bell?

Since start, I dont know what is this wire that comes from inside the pump, I labeled it in this picture.
The original pump also had this wire connected to the small circuit. The pump only runs when connecting Ground and 12+ labeled cable.

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Looks like the other end of the coil winding to me. Does it go up to that solder point?
Do the vibrating contacts work when you put 12 volts to the other thin wire and ground?
 

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Discussion Starter · #39 · (Edited)
Looks like the other end of the coil winding to me. Does it go up to that solder point?
Do the vibrating contacts work when you put 12 volts to the other thin wire and ground?
Now I know the coil winding has obviously two ends, damn I know nothing :-(
I dont know where it goes, I have it just isolated... where should it go? I mean one end of the coil should get +12 volts and the other? (will google it)
The vibrating contacts "pulses" only one time, when I put 12 volts to the +12 wire and ground (+12 I labeled it in the picture)

I also test omhs between this two wires (didnt knew why but now you told that it is the other end of the coil I know) it gives 1,3 omhs (multimeter scale 200)
Tested the same with the original Honda broken pump, and it gives 2,4 omhs
 
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