R33 Gtr - Fuel Pump Voltage Drop

[longex]

Hey guys just pulled out my fuel pump and found to be stock, so will be upgrading soon.

Also decided to check voltage supply to pump as i've noticed few complaints (mainly r32) of voltage drop under load.

Battery voltage varied between 13.3v - 13v

Fuel pump voltage sat around 12.9 - 13v at idle and cruising, but dropped as far as 12.6v when I planted my foot into it.

Anybody reckon this is cause any probs for pump? or should I just direct feed it to battery anyway.

Also looking at Nismo, Tomei or HKS fuel pump. Is there actaully any difference between them. All around the same price.

Cheers

[bigmikespec]

Hey guys just pulled out my fuel pump and found to be stock, so will be upgrading soon.

Also decided to check voltage supply to pump as i've noticed few complaints (mainly r32) of voltage drop under load.

Battery voltage varied between 13.3v - 13v

Fuel pump voltage sat around 12.9 - 13v at idle and cruising, but dropped as far as 12.6v when I planted my foot into it.

Anybody reckon this is cause any probs for pump? or should I just direct feed it to battery anyway.

Also looking at Nismo, Tomei or HKS fuel pump. Is there actaully any difference between them. All around the same price.

Cheers

Don't waste your money, get a Bosch 044 and mount it in tank with a relay so it gets full battery voltage. Look in DIY section.

[R31Nismoid]

^ agreed.

There is a link from the Forced Induction Quick Ref guide how to wire fuel pumps for the proper voltage etc

[MrStabby]

The bosch is a lot cheaper but isn't a bolt in as it doesn't fit the cradle. Jap one should fit well.

[bigmikespec]

Nothing a bit of insertion rubber and a couple of hose clamps can't fix!

[MrStabby]

Nothing a bit of insertion rubber and a couple of hose clamps can't fix!

Yeah true but I reckon fuel surge would be a fair bit worse with that sort of setup. I guess if you dont track it its not a problem.

[longex]

Yeah think i'll spend the extra money and get the jap pump. They seem to flow more than the bosch 044 and fit nice..

Might check voltage difference between alternator and battery in boot. 13v sounds a bit low to me.

[R31Nismoid]

How could it possibly be worse?

[longex]

Thought about the bosch but don't think i want the messing around fitting it. Do you think the 044 can support the same power as Nismo pump?

[James_03]

The 044 will outflow the nismo.

So yes, it will support the same power.

[33GTRV]

Hi. I had a similar problem in my gtr whilst getting it tuned. There is a fuel pump speed controller in some models of the 33, to bypass it, run a ground/negative wire from the pump directly to the chassis/battery. remember, ONLY do the negative as this is what controls the pump speed. Its a 5 min excercise and if it is the fix you were after, then choice. If its not, then hey, 5 mins and 40cm of wire is bugger all right?

Cheers, Allan

[rtune]

yes it is the fuel pump voltage regulator. It keys off the ECU, and varies the pump voltage according to engine load.

Unfortunately it is not able to drive the pump at full load without caving in (which is seen by a big dump in voltage).

So instead of wasting money on a new pump, just wire it to negative and you'll hear it is louder at idle, and you're also recirculating a lot more fuel back into your tank too, which might lead to fuel heating issues if your tank is nearly empty and you are in heavy traffic on a hot day.

but it solves the problem.

[Beer Baron]

my advice is get the nismo pump. they are direct bolt in and work very well and very reliably. I have not seen one problem or failure of one EVER. I have seen a number of bosch pump failures though and others that did not live up to their flow claims. as best I can tell the nismo/tomei/HKS pumps are all the same so chose which ever one you can get quicker or cheaper.

adding a direct feed from battery to the pump (with a relay) is a good idea too. regardless of which pump you get.