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Discussion Starter · #1 ·
Hello,

My dear old original 40 year fuel pump started leaking, she needs a rest... I will have it as a souvenir with a little note in my night stand "old things are better" :cool:

So I could get a new oem one almost the same, as soon as I inspect it I realize it its cheap, with plastic parts... nothing compared with the old one. Anyway, the problem might be adapting it because it came with only two cables (as I read in the forums this is very common issue when replacing fuel pump)

I found this really helpful thread where Switfy shows a picture kind of using an outside relay Fuel Pump solution but cant understantd it good.

Both pumps are the same PSI (less or about than 3 PSI) but dont know what to do with the cables... I might be able to reconnect the thingy I call "circuit board" to the new pump, but would like to know what this board is and if it is the relay... I would prefer to get a new one and adapt it outside the pump case with good new connectors.

Hope you give some light in this matter...

Thanks,



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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.
 

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Discussion Starter · #3 · (Edited)
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.
Thanks! I think I can adapt it, but I know very little electronics, the function and componets (what are for) in this circuit inside. Here I upload some more pics, maybe useful for reference.

This is the new pump (there I marked something), I am afraid... as I read that the fuel pump has a wire (blue) that gives pulses when the rear (or front) coil works, and this "signal cable" conected to the pump circuit board getting pulses if it is not correct or something is wrong connected I might burn stuff or the coil will not work as it should... so, might be better to try to import a new pump like Quantum Frame Mounted Electric Fuel Pump Honda VT700C A / AC 1986 1987, Replaces Honda 16710-MK7-000

Any advise?

Thanks!

Auto part Automotive engine part Carburetor


EDIT: Quantum Fuel Pump, not only died on me, I contact other user from the forum (Alex G) that bought the same pump, it run some kilometers and also died on him the same way, it burnt the contacts and built in circuit. So, the pump might be a piece of shining paper weight or we where just unlucky.
 

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That little black part looks like a diode. Which is a one way check valve so electricity only can flow one direction. Probably a reverse current protection.
 
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Discussion Starter · #5 ·
That little black part looks like a diode. Which is a one way check valve so electricity only can flow one direction. Probably a reverse current protection.
Good to know what is that for! so that diode is in the positive wire just before going in the new pump is kind o f a protection. Now I need to add the old "cirquit board" from the original pump to this new pump.

Would you think I can add the cirquit board to the new pump? just using the new pump positive and negative wires connected to the cirquit board, plug and play?

I guess... I would have first to take out the new pump diode in the positive wire because the cirquit board already have that protection diode?

(I know, if my house get on fire its my fault, I appreciate your kind help as always :cool: )
 

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Discussion Starter · #6 · (Edited)
Hi again! After reading some more the forum, I had little some new info. Hope you can guide me.

The pump I post in later posts, was a 2 wire only pump... so being a good nerd I decided to sell it and get a new one that has 4 wires from USA to Quantum Fuel System QFS (the link I post up there). So... after a month that it take to import stuff in my country and kee down to the custom official telling that the pump is for an old bike and beg to let it enter (I kee mouth closed... dont be naughty:rolleyes:) I got the fuel pump at home.
First, there was a little problem, the connector was male on both ways (QFS told it was a plug and play thing, but no) the pump box has no manual or specs so I had to ask QFS support... at first the were a little unclear short unuseful answered but after insisting they repond)

This is my bike electric wiring (as shown in the electric scheme manual I have for my model):
1) GREEN = Ground
2) BLACK = +12 VOLTS
0) YELLOW/BLACK = Not hooked up to anything.
3) BLUE = Pulse signal wire from the Spark Unit.
Also the manual says the "Black/Yellow and Black" wires jumpered togeather activates the pump for testing purposes, i.e. measure the flow)

This was the Quantum Fuel answer (I added the numbers to match original to new one, thye just answered this 4 lines)
1) Yellow\green=ground
0) Black is not used
2) Red=Positive
3) Yellow=Signal

The original pump kind of started leaking from inside so had to change it, but the little circuit board might still be ok but no idea how to test it), so I left it stored. No problem the new QFS came with it own circuit board.

So at last after replacing the connector to match the original bike installation, I could make it run.

One thing I noticed was that just after turning ignition key and on/off switch to on, you heard the pump "pumping" tak tak tak tak sound until it fills the fuel lines. This behaviour I dont recall being done by the original pump... it did not make any sound but it worked this way always. So, OK, new pump is noisy.

I suppose, first it fills the lines and cuts by the pressure when float level demands, and then when you are running the pump only pumps when it gets Signal impulse on the number 3) wire and/or level/pressure needs.

After runing about 1 or 2 fuel tanks (once some motherfk... turned the fuel valve on to off when I left it in a garage, dont know if this made the pump or circuit get hot or something)... but after a week or two, it stopped working!

(yes I am pissed by an elephant)

So I opened the back of the pump to look for problems and found that it get hot there as you see in the pictures. Also, I would like to add that the original Honda circuit is a 10 in quality and the new pump circuit is a 4 as you can see, really awful)

OK, to make it short (if it is still possible...) now I have a working new pump without circuit and would like to connect it directly to 12 volts, I mean just to these bike fuel pump original connector wires if it is possible:
1) GREEN = Ground
2) BLACK = +12 VOLTS

What I would really want is to know how to add a relay an use also de signal cable as the original, any advise? (explain my like a 5 year old child with candy please :) if its too difficult will go with the two wires only option)
 

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The picture of the black thingy looks like a diode to me. It would be in line with the power wire as a reverse voltage protection device.
You have a diagram there of the earlier system with the relay a separate part before the pump. It has to be that same type electronic relay to work as the factory designed. You could go back to that with your new 2 wire pump.
You might try to use the relay circuit board from the old pump with just the 2 wires going to the pump coil and see if it will work.
 
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Discussion Starter · #8 · (Edited)
The picture of the black thingy looks like a diode to me. It would be in line with the power wire as a reverse voltage protection device.
You have a diagram there of the earlier system with the relay a separate part before the pump. It has to be that same type electronic relay to work as the factory designed. You could go back to that with your new 2 wire pump.
You might try to use the relay circuit board from the old pump with just the 2 wires going to the pump coil and see if it will work.
Thanks @swifty2014 ! I took another look today to the new pump, it rainning like hell since last week (without the circuit burned board) so to replace this board with the original one... but damn... I got electrically lost here, will try to explain my doubt, because I really dont know if the original circuit board is also damaged (looks perfect anyway) or I am connecting wrongly.

Here is the original circuit board, the two arrows I draw there are where the original pump used to have soldered the two wires you see on the other end of the arrows (have to zoom in here, this black cable tube has 2 more wires inside, one insulated and the other not insulated)
The pump you see here is the QFS new pump (the circuit board is the one I post before that got burnt and stopped working, so now the idea is to try the old circuit board with the new pump, as a replacement)

As far as I could test, if I connect the pump red wire label + to the battery + and the green/yellow labeled - to the battery - (ground) the pump just works continously.

If I invert these cables, the pump also works! sorry but this means that if I connect it inverted it will pump the fuel "the other way"? (stupid question sorry)

Now, here the real real doubt :) What is the un-insulated cable that I marked with a ?
(these two cables where soldered to the board, dont know the order so thats why I need to know what is what... I think)

Sorry I know I am a puzzle writing...

Thanks!

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Would need a closer picture of those wires on a clearer background. That little board could be the ‘relay’ everyone talks about that only runs the pump at certain times. You question also wasn’t stupid. The inside of that pump isn’t a rotary wheel, which would run backwards. It’s like putting your finger over a hole and then ‘tapping’ the hole really fast. So there should be no way it would go backwards. Never tried it, though… 😉
 

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Discussion Starter · #10 · (Edited)
(thanks @Troy Jollimore for your answer)

But I really like my tablecloth 😝

Here I upload some more photos, tell if they look better if not can try again!

Yes, that little board is the relay in VT700c 1986 model, uploaded 2 photos front and back of it (almost sure its the relay, because that blue wire that is the "signal" wire, on my first puzzled posts I uploaded each wire function as told in the manual)

OK, I knew that the pump wont pump backwards if it is connected inverted + and -, but my mechanic friend told me that and thanks for confirming that was bulls#it :p Anyway, the pump alone, if you connect it in inverted "polatity" lets say... it works anyway (dont know why electrically talking)

(open them in a window)
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Beige little cylinders are resistors and the coloured lines represent the values (for example the nearest on is red = 2, black = 0, orange 000 gold line is tolerance in % that translates to 20,000 ohm
The 3 pin black thinkg is a transistor (in this case a thiristor CR3CM pdf, CR3CM description, CR3CM datasheets, CR3CM view ::: ALLDATASHEET ::: )
The black cylinder with the silver line is a rectifier diode (the silver line indicates the + side)
The transparent red and black is a Zener diode
Green bulky thing is a ceramic capacitor
 
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So that is just a single wire coming from the pump. They’ve just soldered two onto it to form a make-shift three-wire connection. Even seasoned mechanics can be a little iffy on electrical/electronic stuff. It works because it doesn’t matter which way the current flows, since it’s only operating a plunger. If it were a motor, inverted would make the shaft turn in the opposite direction.
 

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Discussion Starter · #13 ·
Beige little cylinders are resistors and the coloured lines represent the values (for example the nearest on is red = 2, black = 0, orange 000 gold line is tolerance in % that translates to 20,000 ohm
The 3 pin black thinkg is a transistor (in this case a thiristor CR3CM pdf, CR3CM description, CR3CM datasheets, CR3CM view ::: ALLDATASHEET ::: )
The black cylinder with the silver line is a rectifier diode (the silver line indicates the + side)
The transparent red and black is a Zener diode
Green bulky thing is a ceramic capacitor
Thanks @Husoi, now will see the specs of each stuff will test it someway! :geek:(y)
 

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Discussion Starter · #14 ·
So that is just a single wire coming from the pump. They’ve just soldered two onto it to form a make-shift three-wire connection. Even seasoned mechanics can be a little iffy on electrical/electronic stuff. It works because it doesn’t matter which way the current flows, since it’s only operating a plunger. If it were a motor, inverted would make the shaft turn in the opposite direction.
Thanks Troy! sorry to contradict you from my ignorance, but from the pump there comes out two wires, from this black wire tube, inside comes two separated a wires. I know by testing that if I connect the negative (green/yellow) wire to the negative battery port and one of the wires from the black tube... the pump works. If I use the other wire from within the black tube the pump dont work it "shortcircuit" (I just give it a little test but clearly that way do not work), so what is that other cable? (dont understood that about tree-wire connection, will try to research more on that)

I understood that about the operating like a plunger, thanks for the explanation!

Will try to test a little the components (but "think", recall from somewhere, that if they are connected altogether I cant test them just like if the where alone by its specs because that changes. But no worry, this clearly is over my electrical knowledge). After testing this, will try to reconnect the new pump with the old board (testing the two possibilities, I mean the black tube that has 2 wires can be connected to the board in two ways)

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Pump has Yellow/Green as negative, then from the black tube comes 2 more wires, one of these wires (the red one) is the positive, the other I dont know. These 2 wires must be soldered to the board where the 2 red arrows comes out, but dont know which on which. Sorry for the mess, thanks for reading!!! hope at least the pictures helps someone (I am little puzzled here, but will try)
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Thanks @Husoi, now will see the specs of each stuff will test it someway! :geek:(y)
The use of a Zenner diode suggests some kind of safety device to prevent the pump from staying active when there is enough pressure.
A Zenner diverts excess of voltage in a circuit which is what would happen if the pump would try to increase the pressure over a certain limit. Then the Zenner will cut the circuit preventing its damage.
The capacitor would work as a voltage compensator, if there was a spike but goes down quickly then the capacitor will absorb the current if a longer period in overload then the capacitor fully charge and the zenner get to work.

A thyristor (the black 3 legs bit) is a solid-state semiconductor device with four layers of alternating P- and N-type materials. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed.
 

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Discussion Starter · #18 ·
Here's some reading material: 1986 vt700c fuel pump replacement question

The wiring of yours looks to be the same, only the Amazon picture I saw of that model number Quantum pump has a 4-wire connector as well?
Really interesting post you gave me! I did not find it before :-( sorry.

Yes, the pump you see there is exactly the same I purchased (and died after some rides as post before). So the wires are the same, and the answer from the pump maker about the cables is the one I post at up here.

Will read again and do some more tests, if it works or not... will post back later! (if explotes... well will tell my mom to post back but she only knows how to use the telephone, will take time)

Thanks!!!
 

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Discussion Starter · #19 ·
Okay here I am again, the karma motorbike man again!

Unfortunatelly the original circuit board might have a random failure and it pumps some and stops (it even do not work the "force" function shown in manual where y ou join Bl / Bl-Y (Black and Black-Yellow) wires from the pump to make it run continuously.

So... will have to take all the damn tubes, connectors, clamps and clean my blood from the frame (yeah I always get cuts but dont worry I already have the sputnik vaccine :oops:)

I think I will have to go back to the initial plan... just install the pump without the circuit board, with only 2 wires:

1) GREEN = Ground
2) BLACK = +12 VOLTS

And leave the Blue/Signal wire insulated alone.

Damn luck and ignorance, I am getting tired :cautious:

Thanks for all your kind help!
 

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Discussion Starter · #20 ·
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.
Hi again :cool:@swifty2014 ,

If I would like to go back to the earlier system wiring... can I adapt it to my bike? I would like to add an external relay for the fuel pump, do you think it is possible having in mind that my new pump side has only Ground and 12 volts wires, and the bike side connector has 3 wires being:
1) GREEN = Ground
2) BLACK = +12 VOLTS
3) BLUE = Pulse signal wire from the Spark Unit.

So... would it be possible to add a "relay" between the pump and the bike connector? (or is it a complete different stuff, dont touch you will blow the bike :geek:)

Thanks!
 
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