7A fuel pressure testing and figures

[steve briance]

Yes i did do the pump. It was before i had built up experience with the car and pre this forum so i was guided by what came up on the listings. It still comes up on the AutoDoc website today for the 20V.

[mcandmar]

It should be more than up to the job for a 7A assuming its healthy.

[steve briance]

800ml delivered in 15 seconds and it pumped the gauge round to 7+ bar when the other end of the tester was blocked off by accident.

I may try another FPR and see what happens.

[mcandmar]

I assume you tested that from under the bonnet? Just to rule out a clogged up fuel filter or pinched fuel line..

[steve briance]

Yep! I'd thought About that and tested it where it goes into the rail.

[Jonas_R]

I have logs of fuel pressure, boost, rpm etc from my s2 coupe rs2 setup with 7a fpr. I can try and did them out?

[Jonas_R]

Attached excel log and graph. Logged with Zeitronix

[steve briance]

interesting data but doesn't make much sense to me I'm afraid!

I can see the 7A FPR running at 3.5bar until you floor throttle then it seems to build to 5+bar and stay there.

what pump are you running? your legend tells me that all of your cars have way more power than mine so i think your fuel requirement is probably more significant

[Jonas_R]

I'm sorry I thought you had a s2 with 7a fpr and wanted to show what numbers you could expec

Anyhow I don't understand why you think your fpr is broken?
I would say the first gauge is off a bit.

At idle engine running I would say you have around 0.6 bar vacuum so it seems ok with 3.4 bar. If you then remove the vacuum hose from the fpr it will see atmospheric pressure and that should result in close to 4 bar at the fuel rail.
Is that not what you are seeing with 2nd gauge?

I

[steve briance]

I think the first gauge is off a bit too.

The factory figures are meant to be 3.8bar rising to 4.2 bar without vacuum so you are right, the second gauge is not actually too far off but it is still nearly 0.5bar and that is an increase of 17cc/min when running for the 034MotorSport injectors. Would you notice the difference? maybe, maybe not.

I'm only thinking things are only slightly lean as my spark plug insulators look clean and white and for me, there should be a very light coating on them and as they are, they look hot/lean.

[Jonas_R]

If you don't have the vacuum hose on the fpr but just atmospheric pressure then why should it change? I would say it should stay at 3.9 bar.

I mean rail pressure = FPR - [engine pressure] so if hose is off pressure should stay the same. If hose is one then fpr pressure will follow the engine pressure, which on a NA car would go from vacuum towards atmospheric pressure or 0bar relative.

So what I'm missing here?