Hi guys,
I'm a bit confused about the fuel pressure on my car. It's a BMW engined car and should have 3.5 bar approx at the fuel rail when it's
under load. I've recently changed the fuel pump as when I took it for a run on the rolling road the fuel pressure was dropping right off after
5000rpm and the guys said it was the fuel pump. It was a cheap ebay 044 copy which I've replaced with a genuine Bosch 077 unit. The pressure is
now 2.5 bar at the rail all the time. Doesn't matter what revs the engine is at, whether the vacuum line to the regulator is connected or not
it's 2.5 bar. I've replaced the regulator as well with a new BMW 3.5 bar unit. I've also checked the results using two different
gauges. I also removed the filters to check it wasn't that either.
I'm confused! The engine seems to be running okay but maybe a bit lean as I'm getting a few pops in the exhaust...
Advice appreciated...
Chris
077 is a Diesel pump with an operating pressure of 1.5 bar.
quote:
Originally posted by big-vee-twin
077 is a Diesel pump with an operating pressure of 1.5 bar.
That pump operates at 3.0 bar, so with a few losses in your system like filters and bends these would reduce this.
So I don't think your going to get 3.5 bar.
The 044 gets up to 5 bar.
[Edited on 18/4/19 by big-vee-twin]
Is pressure not dictated by the regulator and/or other restrictions? The Bosch website says the pump flows 168 lph @ 3 bar to 135lph @ 5 bar with a maximum operating pressure of 7.2 bar. I have a 3.5 bar regulator so the pump should be operating at 3.5 bar giving a flow of approx 150lph.
pressure is set by the regulator, not the pump UNLESS the pump is not capable of maintaining the regulator pressure.
lockout pressure on a Bosch 070 is 7bar, so shouldnt be an issue assuming the pump is genuine bosch and it has a solid 12v supply (or more) and the
feed to the pump is 12mm bore NOT ADAPTED TO 8mm. The pump is gravity fed, so it must be below the tank, outlet at the base of the tank.
quote:
Originally posted by BaileyPerformance
pressure is set by the regulator, not the pump UNLESS the pump is not capable of maintaining the regulator pressure.
lockout pressure on a Bosch 070 is 7bar, so shouldnt be an issue assuming the pump is genuine bosch and it has a solid 12v supply (or more) and the feed to the pump is 12mm bore NOT ADAPTED TO 8mm. The pump is gravity fed, so it must be below the tank, outlet at the base of the tank.
quote:
Originally posted by CTLeeds
Yep, that's what I thought and is my setup exactly. Only 2.5 bar at the rail though.
quote:
Originally posted by BaileyPerformance
quote:
Originally posted by CTLeeds
Yep, that's what I thought and is my setup exactly. Only 2.5 bar at the rail though.
Are you using a basic capillary type gauge? Removing vac pipe has zero effect?
What fuel filter are you using - 2 connections? (in/out)
Pump has a constant tone?
One thing you haven't answered is what are the pipe sizes?
quote:
Originally posted by Schrodinger
One thing you haven't answered is what are the pipe sizes?
quote:
Originally posted by CTLeeds
quote:
Originally posted by Schrodinger
One thing you haven't answered is what are the pipe sizes?
8mm. Same as the original donor pipes.
Cheers
quote:
Originally posted by BaileyPerformance
quote:
Originally posted by CTLeeds
quote:
Originally posted by Schrodinger
One thing you haven't answered is what are the pipe sizes?
8mm. Same as the original donor pipes.
Cheers
Pump feed pipe must be 12mm
What pressure regulator are you using?
quote:
Originally posted by theduck
What pressure regulator are you using?