Fuel pump up-grades

[mitsiboyblue]

Hi all, Any thoughts if i was to upgrading the already fitted walbro 255 in tank pump?
What BHP are these good for as im worried of 'leaning out'
Dave O


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[Nick Mann]

The 255lph should be good for well over 400, possibly closer to 500.

[mitsiboyblue]

The 255lph should be good for well over 400, possibly closer to 500.

Nick Mann:
Do you think i can use this pump on mine or is the flow rate too high for my standard lines?
See Attached picture d3f440d7d64a18e57fe3a74312387a39.jpg

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[mitsiboyblue]

The 255lph should be good for well over 400, possibly closer to 500.

Its funny how time off the road kills off things on the car.
Boost gauge, fuel pump knackered, and battery all dead.

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[Nick Mann]

No idea, but it seems excessive. The pressure regulator will need to let enough fuel through so you don't over fuel through raised pressure.

[mitsiboyblue]

No idea, but it seems excessive. The pressure regulator will need to let enough fuel through so you don't over fuel through raised pressure.

Oh! including the turbo timer..... lights up won't count down just shuts off with the key?
The Walbro fuel pump picture i sent over has another 200 letres ph more and 20% more efficiency, only wondering if you'd had any experience of that particular pump thats all.
If it can be safely regulate i will be happy for it to stay on just dont want to be wasting money. It will be there for any future mods i might do so will let you know on that.
Asking recently a lot of questions because i might think i know everything but i don't so im bringing you guys on this journey with me and appreciate any advice where you think i might be going wrong.
Dave O




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[Nick Mann]

A good fpr should do it. The stock one won't.

In my head the fpr is the restriction in the system to hold the pressure where you want it to be, the pump needs to flow more than the injectors are firing and not more than the fpr can bleed off. A 255lph should be plenty to flow more than the injectors need but I have no experience or knowledge of how much flow an fpr can bleed off. Presumably at some point the return pipework becomes the restriction. Either way if the flow can't be bled at the right amount the pressure in the fuel rail will rise and the injectors will flow more fuel on the same duty cycle.

I'm waffling a bit really and I expect you know all that already. Sorry I can't be more specific.

[mitsiboyblue]

A good fpr should do it. The stock one won't.

In my head the fpr is the restriction in the system to hold the pressure where you want it to be, the pump needs to flow more than the injectors are firing and not more than the fpr can bleed off. A 255lph should be plenty to flow more than the injectors need but I have no experience or knowledge of how much flow an fpr can bleed off. Presumably at some point the return pipework becomes the restriction. Either way if the flow can't be bled at the right amount the pressure in the fuel rail will rise and the injectors will flow more fuel on the same duty cycle.

I'm waffling a bit really and I expect you know all that already. Sorry I can't be more specific.

Not at all i appreciate your waffling lol , I'm not running the standard fuel regulator, that was binned off years ago but not running a branded one either but its been working just fine until it came off the road, some time ago now to be fair. Standard sized fuel lines but now with a worn out Walbro 255 in the tank by the looks of things.
Maybe ile just stick with the walbro 255 again im not sure







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[Nick Mann]

Defo a dodgy pump? There is a relay on the bulkhead that changes the voltage at the pump from 7 to 12 iirc. Hope you get it sorted.

[swinks]

It all depends what is you bhp goal and injectors size.
From my ewxperience...
- 340lph pump (Aeromotive) was nearly overkill for standard injectors. My Tomei fpr barely could cope with increase fuel flow. It was very tricky to set up right pressure, very sensitive. Mods to return lines would help, but never got into doing it.
- 255lph is perfect for standard size injectors and stock return lines. Also popular upgrade for 560cc (Evo) injectors are good match for 255lph fuel pump

- suggested 455lph pump is way too big. It won't work without change of return lines, and mods to fuel tank syphon and parallel injector rails. Necessary if you going way over 600 bhp.

If you are concerned about fuel pump size, I would recommend AEM 320lph pump and top quality fpr to cope with (i.e. Tomei)

[mitsiboyblue]

It all depends what is you bhp goal and injectors size.
From my ewxperience...
- 340lph pump (Aeromotive) was nearly overkill for standard injectors. My Tomei fpr barely could cope with increase fuel flow. It was very tricky to set up right pressure, very sensitive. Mods to return lines would help, but never got into doing it.
- 255lph is perfect for standard size injectors and stock return lines. Also popular upgrade for 560cc (Evo) injectors are good match for 255lph fuel pump

- suggested 455lph pump is way too big. It won't work without change of return lines, and mods to fuel tank syphon and parallel injector rails. Necessary if you going way over 600 bhp.

If you are concerned about fuel pump size, I would recommend AEM 320lph pump and top quality fpr to cope with (i.e. Tomei)

Thankyou guys, i will scrap the idea and look into 340lph pump or stick with 255

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[Confused]

If you're only checking pump flow/pressure at idle, you may find it a touch low - the relay/resistor pack on the bulkhead drops the voltage to the pump at idle. I thought I had a pump or FPR failure on my Anglia, but it turns out my pump was running at about 7 volts (due to a different mis-wiring) - modified that to run at full battery voltage all the time, and pressure even at idle is exactly where it should be.

[mitsiboyblue]

If you're only checking pump flow/pressure at idle, you may find it a touch low - the relay/resistor pack on the bulkhead drops the voltage to the pump at idle. I thought I had a pump or FPR failure on my Anglia, but it turns out my pump was running at about 7 volts (due to a different mis-wiring) - modified that to run at full battery voltage all the time, and pressure even at idle is exactly where it should be.

Yes I'm only checking fuel pressure at idle, not raced the engine as it's a completely fresh build. i will check out that resistor on bulk head and also the voltage at the pump before replacing it anyway.

Dave O

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[Confused]

Ah, another thought - have you had the alternator disconnected at all? When I put my engine back in last week, I took it out for a spin and it wasn't quite right, not idling quite correctly, and low fuel pressure on the gauge - when I came back I noticed that I'd not reattached the alternator wiring! Reattached it, and fuel pressure sitting right back where it should have been, and idle was smoother!

[mitsiboyblue]

Ah, another thought - have you had the alternator disconnected at all? When I put my engine back in last week, I took it out for a spin and it wasn't quite right, not idling quite correctly, and low fuel pressure on the gauge - when I came back I noticed that I'd not reattached the alternator wiring! Reattached it, and fuel pressure sitting right back where it should have been, and idle was smoother!

Yes ive had alternator off and connected it but not checked charging output at battery. i will be doing a full electrical check of the battery, alternator, fuel pump inc resistor over the weekend. All food for thought.
Cheers, will be letting you know my findings soon!

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[mitsiboyblue]

Ah, another thought - have you had the alternator disconnected at all? When I put my engine back in last week, I took it out for a spin and it wasn't quite right, not idling quite correctly, and low fuel pressure on the gauge - when I came back I noticed that I'd not reattached the alternator wiring! Reattached it, and fuel pressure sitting right back where it should have been, and idle was smoother!

Hi alternator connected all nice and tight battery charging at 14.31volts the battery was starting the engine but 'shot'. Swapped out with new battery but still had low fuel pressure. bypassing the fuel pump resistor which improved it slightly but cant get it above 30psi.
The pump runs quiet in the tank so my suspicions are and guessing its generally tired and going to fail soon.
Ordered new pump and will be replacing filter at same time.
Fingers crossed....
Dave O

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