Too big a fuel pump???

[Warpspeed]

It sure does on a lot of cars.

Try measuring the actual voltage across the fuel pump, do not be surprised if it is 11.5v or something on some cars. With the engine running at anything well above idle, there should be about 14.0 to 14.2 volts right at the battery.

So you use the original fuel pump wire to operate a relay instead of the pump, and run a pretty big thick wire straight from the main fuse-box to the relay, and then to the pump. This is usually a lot easier than rewiring the original fuel pump circuit.

If you can increase the voltage from 11.5v to 14v, that is nearly +22%, and the motor current will also increase 22% at the higher voltage. Pump power goes up about 49% in this example. The difference this can make to pressure and flow has to be seen to be believed.

Replacing the stock pump with a monster aftermarket pump will usually increase the pump operating current, so check the voltage at the pump. You may not actually be getting all that extra pump performance you paid for.

[GTR-Ben]

Well this must be doing something, because with a stock GTR pump and a fairly decent wire straight to the battery, the pump is flowing enough on it's own to fuel this car with 720cc injectors and holding pressure with some big boost on the big T88 34D..

Running it down the track on Sunday with the engine rebuilt, so we will see just how much you can get out of a stock GTR pump.

In fact I have seen 2 GTR's running stock pumps that have been rewired and both are running low 11's on street tires etc..

Makes you think..

[Sydneykid]

Hi GTR-Ben, I never underestimate the standard GTR fuel pump. they are certainly a good thing. But, I have tested a number of them and they consistently flow a little more than the stated figures. So sure, you can use them beyond what most people do.

The bottom line for me is, if I had just spent $12K on a turbo kit (retail for a T88-34D) why wouldn't I spend another $150 (net) on a larger fuel pump? After all what is this in comparison to the cost if it runs out of flow?

Insurance, I think it is called and $150 for $20K insurance is pretty cheap I reckon.

[GTR-Ben]

I agree Sydney Kid, thats why I upgraded the fuel system on the car today.. just to be sure.

Just seemed very odd that the stock pump could be pushed so far.

We will see how it really does tomorrow at the drags..

[gtstii]

I've finally decided to get a gtr fuel pump after all of that! Reasons are that the Walbro's sound like they might not be too reliable and the bosch's are too loud for my liking.

I have 2 options, a second hand r34 gtr pump for $300

or

a BRAND NEW r32 gtr pump for $400 (from nissan these are normally $900)

I was thinking of getting the new gtr pump and fitting it myself, it's good cos it's meant to be a stright fit into my bracket!

[gtstii]

so you reckon i go for a new pump or the second hand one?

[benm]

new

[gtstii]

new

yeah I know, huh....

by the way, thanks for your response to my pm and your info on your 040 pump!

[benm]

np

[Busky2k]

Heres a nice cool graph of the various flow vs pressure of the walbro pumps I came across; (Although it doesnt agree with the tables from other websites)

http://www.2gnt.com/www/corbin/example4.gif

[lukits01]

hey, I have a R33 GTS-T that I want to pump up to 200rwKw

was thinking of purchasing a 2nd hand GTR fuel pump

do I need a fuel pressure regulator to accompany this? or would the stock ones do?

Im sure a GTR pump would be more than enough for my needs is there anything wrong with this idea?

[benm]

No u wont need a fuel reg.

Yes it will be enough but how old is the GTR pump and how much is it worth? You might be better off getting a Bosch 910.

[SeD]

hay sydneykid u know alot about skylines...

i can only gather from ure knowledge that u work with skylines alot... ie. u r a mechanic of sum sort

how much do the bosh fuel pumps go for these days

[lukits01]

the reason I'd prefer a GTR pump is because they are a straight fit replacement of the stock pump. they seem to go anywhere between 170-400 depending on condition

how much are Bosch 910? and is it difficult to install?

[gtstii]

same reason i like the gtr pumps, straight fit and are quieter than the bosch's.

You can get them second hand or there's a place in Vic which sells them brand new for $440 each. I'm getting one and I think if we were to get them together we might be able to get them cheaper.

pm me if interested!

[BU5TER]

sorry guys to bump such a old thread but I am having trouble working out the flow /hr of a 044 pump, I have noticed SK and others have quoted it to flow 330l/hr but when I check on the bosch website it quotes only 200l/hr where is everyone getting there flow rates from

Brett

[BBQ]

In the race GTST we have a GTR pump as the lifter to the surge tank and a Bosch 044 supplying the fuel to the engine.  It is solidly mounted to the boot floor, has braided lines and an inline filter all bracketed to the floor and it makes a huge racket.  Even with my helmet on and at full noise I can hear the thing rattle away when the surge tank is empty.  It makes a good safety warning.

Previously we had 2 X GTR pumps mounted the same way and they made much less noise.

It’s easy to fix the noise problem, Have done so before, Rubber mount the surge tank with (rubber spacer places) and Sleeve the 044 Pump with a silicon sleeve, Doesn’t stop the noise, but reduces it dramatically.

As for people wanting to put out series power, Its silly trying to run So Called "Bigger" walbro and bosh pump" in tank. If you have spent lots of money on engine setup, eg Internals, turbos, so on, Its really not that much more to put a newer "pump eg, Walbro or Bosch in tank to fill a Surge tank setup, with a Bosch 044 or 2 if needed. Because you won't get the same performance running a pump directly from the tank and trying to run 70 - 80 psi rail pressure.

Theirs no cutting corners when it comes to EFI, as it can kill a motor easily if you get the slightest drop in pressure at 30psi Boost.

[Beer Baron]

sorry guys to bump such a old thread but I am having trouble working out the flow /hr of a 044 pump, I have noticed SK and others have quoted it to flow 330l/hr but when I check on the bosch website it quotes only 200l/hr where is everyone getting there flow rates from

Brett

the only thing I can think of to account for this is the pressure at which these figures are quoted at. ie. a pump that can flow 200l/hr at 80psi will flow a lot more than one quoted to flow 200l/hr at 50psi. Also apparently different companies use different liquids to test their pumps so this can affect readings too.

[Sydneykid]

A Bosch 044 pump is rated at 12 volts for 200 litres per hour at 73.5 psi (40 psi fuel pressure plus 33.5 psi boost). If it is not pumping "against" that pressure the flow increases, it isn't linear either (ie; 36.75 psi is more than 400 litres per hour). They are around 10% conservatively underated. Plus I run mine at 13. 8 volts, being the alternator output voltage.

For a practical test, I measured the return flow (from the fuel pressure regulator to the tank) on a 650 bhp engine. There was enough fuel over supplied for at least another 100 bhp. So I believe the 730 bhp rating to be reasonable, as long as the rest of the fuel system is up to it of course.

Hope that helps:cheers:

PS, that engine was running Elf LMS, results may differ with other fuels.

[fresh]

at what point on a gts-t will the fuel pump need to be upgraded, and from there the injectors and regulator ???