How to test fuel pressure?

[Glen Chamberlain]

Can any one tell me the best way to test the fuel pressure in the fule rail on an ABY? I havn't noticed a nice handy car type tyre valve that is on some systems? Iam experienceing slight hesitation at high RPM and extraordiaary fuel economy! 38.2mpg!!!

[Doug_RS2]

Running too lean?

Vag-Com the lambda or measure the voltage (I don't know what Volts it should be)

[Sweeper]

Glen: If it's somekind controlable , please , please , please record your position. A lot of us would like to get such economy settings sometimes .

[S2central.net]

Tis in the ABY/AAN manual. I have it at home. Needs a funky pressure tester with correct adapters, but you (Glen) might have access to something in work...

Paul

[Glen Chamberlain]

Maybe i could mod my oil pressure tester or somthing? not really sure yet? But what sort of fuel pressure should i be looking for? And is the FPR adjustable!

(Maybe this could be a contributing factor to the hestation and miss i have at high engine speed under load?!)

[Glen Chamberlain]

Iam gona order some adaptors on monday to tap into the fuel line so i can use my oil pressure tester to test the fuel pressure. Ive been looking for the correct pressure and found this on good old s2central!

"The ABY engine uses slightly higher fuel pressure and higher flowing fuel injectors than the 3B. The ABY runs at 4.0 bar above manifold pressure whereas the 3B runs at 3.5bar above manifold pressure. pump. "

So does this mean that with the fuel pump bridged out and the engine off, then i should see 4.0 bar or 5.0 bar of fuel pressure? and if I charge the FPR with 1.0 bar then should i see 5.0 bar of fuel pressure or 6.0 bar?

Can the FPR take up to 2.0 bar of applied air overpresure? (3.0 bar absouloute)

Will there be less than 4.0 bar of fuel pressure when vacume is applied to the FPR or does it only work with positive pressure?

Questions Questions Questions!
Sorry Guys!

[audiman]

Not sure about that little lot Glen, but I did test my Fuel pressure yesterday!! I have a 4 bar pressure reg on my 3B, and at idle, I was getting 3.8 bar. When I applied some pressure, ie boost, the FP rose to over 4.5 bar, could not drive the car as the gauge doesn't have a long enough pipe, but this shows that the pump and reg. are working OK.

I dont know about the ABY engine have not had dealings with one, sorry.

I had hoped to find something wrong with mine as it still doesn't run right. Oh well. At least its another item that is OK I will find the problem with it.

Glen, have you had the injectors cleaned? That can cause a hesitation. Just a thought.

[Glen Chamberlain]

Thanks for that! I havn't cleaned the injectors but the problems are only apparnat since ive had it chipped. Not saying in anyway that the chip has caused or is the fault but what iam saying is that mabe for instance that the car now chipped, requires more fuel but the FPR or pump cant deliver it? Maybe it was on its limit before with the stock set up but just managing to cope, but now its pushed it over the top?

The ABY has the 4 bar FPR on same as yours so our comparisons should be similar. What pressure was there with the engine stopped, but pump running? and where & how did you tap in the fuel line?

Thanks!

[audiman]

I never tried it just with the pump bridged and engine stopped. Sorry.
I ahd a right mare connecting it up. All my connectors were the wrong threads!! Managed to bodge it in tho, thats another reason i didn't drive it!! LOL

3B fuel fail is totally different to the ABY so I cant help on that. sorry again!
But if it does help it was connected before the FPR.

I thought that ABY's used the same fuel pressure? And the mod for chipped cars is to use the RS2 FPR? Maybe i am wrong on that.

Checked flow rate as well, i think it said in the book 960ml in 30 secs. Whatever, it was about a litre.

[Glen Chamberlain]

Well finaly tested the fuel pressure! I tested it @ the flexy supply hose to the rail. I used a standard oil pressure tester to test but i needed to get an adaptor fabricate to "T" in to the line. (£25!!!!!) I cleaned the oil tester first and took readings at different pressures, as follows:

@ tickover 3.8 bar
stopped 4.0 bar
With 0.5 bar of simulated boost = 4.7 bar.
With 1.6 bar of simulated boost = 5.6 bar.

This was tested on an ABY with a stock FPR. Seems good to me!

[audiman]

Sounds good to me mate. Thats what i get on mine.