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General Information => General => Topic started by: burn_your_money on February 08, 2007, 03:25:00 pm

Title: Gas mk2 in-tank pump
Post by: burn_your_money on February 08, 2007, 03:25:00 pm: Does anyone know how many PSI the stock gas in-tank pump puts out? I did a bunch of searching and all I could come up with was "hardly any, easily under 20 PSI"
I was thinking it would be a pretty easy upgrade to the diesel
Title: pump pressure
Post by: jimfoo on February 08, 2007, 03:53:25 pm: You could always add a small return line and a tee, then a pressure regulator to the IP. Then it wouldn't matter much. I don't know about VW pumps, but most EFI pumps put out 35-90 psi, way to much to plumb straight in.
Title: Gas mk2 in-tank pump
Post by: burn_your_money on February 08, 2007, 04:17:51 pm: I'm hoping for a dirt cheap/free upgrade that requires as minimal amount of modifying as possible, which is why I was hoping to go without the regulator.

I know that most EFI pumps are high pressure, but since this one is the lift pump for the main pump I was hoping that it would be within a good range
Title: pump
Post by: jimfoo on February 08, 2007, 04:38:23 pm: Then you would probably be ok. I'd just chech the pressure before you do much driving.
Title: Gas mk2 in-tank pump
Post by: wyldman on February 08, 2007, 05:46:11 pm: The small in tank transfer pump is fairly low volume.Pressure is only created when you have restriction.You would need to deadhead the pump and measure the pressure to see.Because it is low volume,it will take a while to build full pressure.It also may self regulate when deadheaded,due to pump inefficiency.The pressure it self regulates at will still probably be too high to feed the injection pump.Most will see 40-50 PSI when deadheaded.

I would tee in a needle valve,or a fixed orifice into the return line right at the injection pump.This would regulate pressure,and also easily bleed air from the system for easy priming.Add a pressure gauge to adjust the valve or orifice until you find the right size.You only need a few PSI at the injection pump to keep it happy.Any more might damage the pump.
Title: Gas mk2 in-tank pump
Post by: RabbitJockey on February 08, 2007, 06:54:49 pm: i would just use an external universal unit, i think they're fairly cheap at places like napa i'm not sure though. it'd be an easy install too, just a switched 12vs and a ground
Title: Gas mk2 in-tank pump
Post by: burn_your_money on February 08, 2007, 07:11:09 pm: 5-7 psi is ideal right?
Title: Gas mk2 in-tank pump
Post by: wyldman on February 08, 2007, 08:41:12 pm: I don't know the exact specs on the VW pumps,but most of the rotary injection pumps like around 5 psi.Some will tolerate up to 15 psi,but I don't think the VW internal lift pump would like it.
Title: Gas mk2 in-tank pump
Post by: anarchyx34 on February 08, 2007, 09:35:58 pm: My car was a gasser at one point so I kept the in-tank pump and just have the fuel pump relay grounded so when the ignition is on, the pump runs. Never had a problem yet, and it makes purging air from the fuel lines a breeze.