Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Is it worth upgrading my fuel pressure regulator if I haven't got any other mods on the engine?

I was thinking of doing that to my V6 as well, as over time they can lose efficiency apparently. Looks a pig of a job though, no idea how to replace it.... The one on there is totally different to the pictures that you see of the ones for sale.

The stock V6 uses a 3.0 bar rated FPR. Due to age/deterioration, this commonly reads 2.5 to 2.8 bar. An uprated fuel pressure regulator can be installed to improve throttle response by increasing fuel pressure supplied to the fuel rail and injectors. This does not increase the amount of fuel delivered as the Motronic ECU indirectly detects the increased fuel pressure (over fuelling at the lambda/O2 sensor) and uses a shorter injection pulse cycle to deliver the required fuel dose instead.

Piece of piss to remove/replace. Depressurise fuel rail, detach vacuum hose from FPR, loosen clamp, remove. Done. Five min job. I put a 4-bar VAG FPR on mine.

Incidentally, you can actually test the efficiency of the fuel pressure in your system. You can get a fuel pressure gauge and put the vacuum hose that goes on to the FPR on to it. Fire up the engine and marvel at the fuel pressure reading. If it's the FPR itself that you're worried about then a 3.8 would be fine on a stock lump.

humbucker wrote:The stock V6 uses a 3.0 bar rated FPR. Due to age/deterioration, this commonly reads 2.5 to 2.8 bar. An uprated fuel pressure regulator can be installed to improve throttle response by increasing fuel pressure supplied to the fuel rail and injectors. This does not increase the amount of fuel delivered as the Motronic ECU indirectly detects the increased fuel pressure (over fuelling at the lambda/O2 sensor) and uses a shorter injection pulse cycle to deliver the required fuel dose instead.

Piece of piss to remove/replace. Depressurise fuel rail, detach vacuum hose from FPR, loosen clamp, remove. Done. Five min job. I put a 4-bar VAG FPR on mine.

Clamp? All I saw when I looked at it is the round cylinder with 2 fuel pipes and a vacuum hose coming out of it, which is welded to a frame. How do I actually get to the pressure regulator then?

Also, to de-pressurize the fuel rail, I presume I just undo the dust cap and press the valve in with a rag over it, to soak up any escaping fuel?

Cavalier342 wrote:The one on there is totally different to the pictures that you see of the ones for sale.

This is a pic of my 3.0 bar and 4.0 bar V6 FPRs side by side:

Cavalier342 wrote:Clamp? All I saw when I looked at it is the round cylinder with 2 fuel pipes and a vacuum hose coming out of it, which is welded to a frame. How do I actually get to the pressure regulator then?

The FPR is clamped, one small bolt to remove it. Located drivers side end of fuel rail. Can't miss it. The FPR itself just slots into the housing on the fuel rail. Here is my fuel rail with FPR etc removed:

Cavalier342 wrote:Also, to de-pressurize the fuel rail, I presume I just undo the dust cap and press the valve in with a rag over it, to soak up any escaping fuel?

Yup

Oh I see, it makes better sense, looking at that photo of the fuel rail on it's own.

Thanks fella. I'm on a mission to replace anything that needs to be replaced, and that is on my agenda!

I know it's a old post but is it worth upgrading? Also pictures won't load but would love to see the comparison if still have pictures of rail and fpr?

Sadly, Andrei has not visited the site for three years.

And I have not had any emails or messages for at least two of those years.

I tried it out on my V6 and noticed a change. It's worth doing. They degrade over time and you loose fuel pressure, if you still have your original one it probably needs replacing. If you're going to replace it, you might as well get the uprated one.