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Adding a third fuel pump?


TRD3000GT

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I would think it would take quite a while for a pump to completely ie not pump at all. It would be a long drawn out process. (All my speculation of course) plus if you had a third pump that was there for back-up, you wouldn't need to worry about having lightning quick reflexes.

Essentially what I'm talking about is knowing that a pump is *about to fail*. It would be nice to know before it did then you wouldn't have to rely on no.3 as a back-up. Ya get me?

 

Got ya..

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I would think it would take quite a while for a pump to completely ie not pump at all. It would be a long drawn out process. (All my speculation of course) plus if you had a third pump that was there for back-up, you wouldn't need to worry about having lightning quick reflexes.

Essentially what I'm talking about is knowing that a pump is *about to fail*. It would be nice to know before it did then you wouldn't have to rely on no.3 as a back-up. Ya get me?

 

I know what you're saying but it's how you would know it was "about to fail", which I don't see is something that would be possible to detect until it finally did fail. Then when one pump has failed you've got to detect that it has failed and warn you, if not and another pump fails then you're still screwed.

 

The simplest options are often (but not always ;)) the best. In my opinion that option is two pumps with a protection circuit to kill power to both pumps in the event of failure, rather than having to rely on a complicated system involving warning lights, should one fail but allowing it to still run etc.

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This has long been a point of contention about the twin pump setup - How does one know if one pump has failed short of it leaning off at high duty cycles - and at 6000rpm 1.6bar boost the last thing you are looking at is the fuel pressure gauge. A fuel cut if one failed would be great, but short of putting a flowmeter on the output of each pump (a packaging and wiring nightmare, never mind the logic circuit, never mind the cost) I can't think of a way to do it - but then my electronics is limited to wiring diagrams of cars...

 

Once I bandied an idea about with someone where you got a black box which compared fuel pressure to boost pressure and switched an output if the two varied beyond a fixed window of psi. e.g. if your static is 40psi that means you run 60psi at 20psi of boost. The black box is programmed for a 40psi difference between the two readings, +/- say 2psi. So if your fuel pressure runs lower than 58psi at 20psi boost, it switches the output and does whatever you've wired it up to (buzzer, light, cut the fuel circuit, all 3). This has the advantage of detecting any circumstance that causes a loss of fuel pressure, be it a leak, blockage, your FPR reference hose has blown off, or a pump is failing. If someone can build this you'd be onto a winner - I'd have one :D (for free as I thought of it ;) )

 

-Ian

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Yeah, I remember that idea Ian, I've still got the design logic done, the company I approached to prototype the board wanted £2k to do it, which was a little extreme...

 

However instead of putting flowmeters into the fuel lines, you could use a current measuring circuit... since the pumps should use a pretty much steady current, you could have a tolerance, so that if they go to open circuit it flashes a light. Fairly straight forward...

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What about having the 3 pumps running in normal 9V mode, and the Fuel pump ECU just switching 2 of them to 12V when needed. This would reduce heat build up through fuel flow, and the chances of both the 12V switched pumps failing at the same time would be slim????

 

Or is there anyway you could intergrate a system like Ians using the existing fuel pump ecu

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Alright Chris,

 

I'm about to be doing all this on my own car as well, got the bracket here now, just waiting for a -10 fuel filter to turn up so I can piece it all together. I'm doing it as my 2 Walbros have run out of puff at 1.8 bar, fuel pressure's dropping right off since fitting a bigger turbo. I'll let you know how I get on when I get round to fitting it all. Nice meeting you last week by the way.

 

Ta

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I know what you're saying but it's how you would know it was "about to fail", which I don't see is something that would be possible to detect until it finally did fail. Then when one pump has failed you've got to detect that it has failed and warn you, if not and another pump fails then you're still screwed.

 

The simplest options are often (but not always ;)) the best. In my opinion that option is two pumps with a protection circuit to kill power to both pumps in the event of failure, rather than having to rely on a complicated system involving warning lights, should one fail but allowing it to still run etc.

 

That's my point. It would be easy to set up a electrical system that monitored the increase in current draw as a pump neared failure. I recon for a good few hundred miles the pump would end up drawing more and more current as it struggled to work. That's what I would want to monitor. That way I could replace the pump before it finally failed. The only problem is that you would only be able to test the pump's current draw at full belt. But heh, that happends pretty much every time I get in the car, so not a problem there! ;)

 

Perhaps a combination of both would be the ultimate (but heh who we kiddin' neither of us are likely to build either of these systems really eh?) but pie in the sky stuff, you would want a system that warned you of impending doom, and one that turned the car off when it finally did happen if you ignored the warning.

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Why not go for the Aeromotive Pro-Series Fuel Pump. Flows enough for 1400hp on Turbo setups, 1000 lbs. per hour @ 13.5Volts and 45 PSI. and as they state

 

"Designed for racing, this performance pump simply does not wear out"

 

Just what you want lol

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