Does OEM fuel pump have internal pressure switch?

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DreamV4

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I believed 4-wire motorcycle fuel pumps had internal pressure switch (pump stops pumping when pressure increases), but 2-wire pumps didn't. Now I am not sure about 2-wire pumps (Vmax).
 

02GF74

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I didn't think they were that sophisticated, but they stopped pumping aas the pump is not able to overcome the pressure of the fuel ahead of it.

I, d be extremely surprised if the vmax 2 wire pump has anything more than a solenoid to move a diaphragm.
 

DreamV4

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I didn't think they were that sophisticated, but they stopped pumping as the pump is not able to overcome the pressure of the fuel ahead of it.

I, d be extremely surprised if the vmax 2 wire pump has anything more than a solenoid to move a diaphragm.
that is it! If pump stops pumping a few seconds after turning ign on, there is internal pressure switch.
 

02GF74

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Well that's not how I see it. What I'm saying is that there is no additional component to stop the pump.

It's like me asking you to pick up a large bucket repeatedly whilst I put bricks into it. Eventually you will stop as you won't have the strength to lift it.

Same as the pump. The mechanism is not strong to overcome the pressure of the fuel it is pushing against so the pump stops.

I don't know the purpose of the 2 additional wires on a 4 wire pump.
 

DreamV4

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Well that's not how I see it. What I'm saying is that there is no additional component to stop the pump.

It's like me asking you to pick up a large bucket repeatedly whilst I put bricks into it. Eventually you will stop as you won't have the strength to lift it.

Same as the pump. The mechanism is not strong to overcome the pressure of the fuel it is pushing against so the pump stops.

I don't know the purpose of the 2 additional wires on a 4 wire pump.
non-stopping pumps have internal release valve. Stopping pumps, I think, have internal pressure switch.
 

one2dmax

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The OEM pump will stop based on a few things. A few seconds (5 in fact) after turning the key on the pump will shut off IF it does not sense a tach signal (from either cranking or running). But, it will shut off once it builds up pressure from full bowls and will then slowly click to maintain pressure as the fuel is consumed.
 

maleko89

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Most of the smarts except for the pressure shutoff reside in the the fuel pump relay.
 

redneksoldier

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There is no pressure shutoff. It has a solenoid, plunger, spring, diaphragm, and a couple of electrical contacts inside the pump itself. After having had a couple of these type pumps apart, this is my understanding of how it works...

The tension of the loaded spring forces the plunger to move creating pressure on the outlet of the pump until it reaches the end of its stroke. At this point, the contacts make, energizing the solenoid to draw the plunger and spring back preloading the spring for another stroke. When the plunger hits the end of its travel the other way, the contact opens, de-energizing the solenoid and allowing the spring to once again exert pressure on the plunger and outlet. The cycle will continue until there is sufficient pressure on the pump outlet to resist the spring tension on the plunger (I think about 3psi but I could be wrong and it could vary bike-to-bike). At which point the plunger will stop until some fuel is consumed, releasing pressure and allowing the spring and plunger to continue moving. The diaphragm is basically the valve that facilitates the one-way movement of fuel through the pump.
As Sean said, the fuel pump relay will kill power to the pump after 5 seconds with no tach signal. The spring tension is the only thing that controls fuel pressure.
 

redneksoldier

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non-stopping pumps have internal release valve. Stopping pumps, I think, have internal pressure switch.
I would think that may be the case with rotary pumps, but plunger type pumps do not need either of those things because of the way they function. The coil of the solenoid is actually de-energized while the spring and plunger is creating pressure. Watch the air bubble that forms in the fuel filter while the bike is running. You will see the pulses of the fuel pump. The coil of the solenoid is only energized for the split second it takes to draw back the plunger and spring. You could put a meter in series with the positive wire and set it for amps and watch the pulses that way as well. I doubt most meters are fast enough to get an accurate reading, but you will see the pulse.
 

DreamV4

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Thanks for all responses! Here is a real question:
There is $17 pump, looking like OEM except different bracket.
But I decided to save $7 and bought this one:
Now I need to make decision to buy $17 one or keep $10 pump.,
$17 pump is NOT plug and play, I still need to deal with bracket.
$10 pump is, I believe, non-stop(???) pump.
 

02GF74

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Thanks redneksoldier - you saved me typing that out. That's exactly my understanding of how the pump works, the fuel pressure stopping the plunger from closing the contacts so the solenoid is not powered.

The $10 pump looks like selenoid type, it should stop.

You can test it by attaching a hose into a container of petrol and put you finger on the other end. If it doesn't stop, then shout out a rude word or two followed by "cheap Chinese rubbish".
 

gentsvmax

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Thanks for all responses! Here is a real question:
There is $17 pump, looking like OEM except different bracket.
But I decided to save $7 and bought this one:
Now I need to make decision to buy $17 one or keep $10 pump.,
$17 pump is NOT plug and play, I still need to deal with bracket.
$10 pump is, I believe, non-stop(???) pump.
ok I do believe in saving a buck or two here-n-there, but GOTDAM when are ya cut loose and spend some money on the bike LMAO!
Bet that mod monkey's trembling in the corner hallucinating on an Exactrep binge LOL.
 

DreamV4

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ok I do believe in saving a buck or two here-n-there, but GOTDAM when are ya cut loose and spend some money on the bike LMAO!
Bet that mod monkey's trembling in the corner hallucinating on an Exactrep binge LOL.
More you know, less you pay.
I installed at least 5 pumps like that on different bikes, and they worked fine. I like "outsmarting" ;) bike and car manufacturers.
 
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