How To Test A Fuel Pressure Regulator

[welshpug 1,657]

Thought I'd post up how I did this earlier, Sinbad on here needed a replacement fuel pressure regulator and I wanted to be sure that the one I had spare was working properly.

 

so, what do you need? well I used a Trackpump

 

 

Fit valve head onto fuel rail inlet (Presta size fits nicely) you would need to remove the hose from the fitting to do this so if they are original hoses (hard plastic, coated with rubber) then it would be advisable to get another union or some method to fix the hose to the rail.

 

 

then pump away! It wont take long with a decent pump like this SKS Renncompressor to reach the 3 bar break pressure that the most common GTI's use, some apparently have a 2.5 bar item, I remember a Peugeot Talbot sport mod was to pop a 3.5 bar item on.

 

 

as you can just about see, the gauge went to just over 3.0 bar and the regulator squeaked the excess air out, just to make sure it didn't leak I left the pressure on the rail to ensure it didn't leak.

 

 

Ten minutes later it was still as I left it, so all good! job done.

 

 

obviously this wont test whether your fuel pump is still up to it, or that the one way valve in the pump is working, but still an easy check to do as everyone should have a pump of some kind to hand.

Edited August 29, 2012 by welshpug

[JRL 14 1 Cars]

Have you ever had a broken FPR? not something I hear often on the forum. I have an infamous FSE valve, I bought a gauge and when I had it rolling roaded had it set up to between 3.5 and 4.

[welshpug 1,657]

Not personally but a mate has had a few iffy ones.

 

I'd imagine 3.5-4 is rather too much for decent cruising fuelling.

[petert 586]

When setting up Mi16's to run on std management I always go through the drawer of regulators until I find the best. Even though they're supposed to be 3.0Bar, they typically vary between 2.8 and 3.3 Bar.

 

I thought all Jetronic GTi's were 2.5Bar?

[JRL 14 1 Cars]

I can imagine a faulty fpr can cause all sorts of diagnostic headaches.

It could probably be adjusted to be a bit lower but last mot inspector said the emissions were pretty good and all is running smoothly so I daren't touch it.

[welshpug 1,657]

I always thought they were 3.0 bar, no details on the bosch ecat though, part number from there is 0 280 160 258, I'll check the one I have at home matches, it doesn't state the pressure on the unit.

 

The later snap in fittings you find on XU10's or the plastic inlet 205's, is listed as 3.0 bar, 0 280 160 560.

[Baz 421]

I have a gauge i can add between the fuel line to test.

 

I'd also add after a recent scare with one of mine if you're swapping one, take a look at the condition of the o-ring seal on it too, mine had been on there without problem for over 6k, but began to leak for some reason, dripping fuel down above the alternator...

[Anthony 1,003]

Jetronic GTi's that I've checked have all had the 3.0 bar regulator, which would be the 115hp 1.6's and the 128hp 1.9's.

 

There does seem to be a lot of 2.5 bar regulators floating around though that have clearly come from 205's - could it be that the early 105hp 1.6's and/or the late low-comp 105hp 1.9's used the lower rated regulator? This would tie in with Peter's thoughts as I believe those are Jetronic variants that were sold down under.

 

And yes, they do fail - when trying to work out why Justin (Kyepan's) 205 Mi16 was running lean on the original management we discovered that the 3.0 bar regulator was actually only holding around 2.5-2.6 bar at WOT according to the inline gauge we fitted. Swapped it over with a spare that I had, and it was holding around 3.1 bar and fuelling looked far more sensible.

[marksorrento205 80]

I have a gauge i can add between the fuel line to test.

 

Same

 

Jetronic GTi's that I've checked have all had the 3.0 bar regulator, which would be the 115hp 1.6's and the 128hp 1.9's.

 

There does seem to be a lot of 2.5 bar regulators floating around though that have clearly come from 205's - could it be that the early 105hp 1.6's and/or the late low-comp 105hp 1.9's used the lower rated regulator? This would tie in with Peter's thoughts as I believe those are Jetronic variants that were sold down under.

 

And yes, they do fail - when trying to work out why Justin (Kyepan's) 205 Mi16 was running lean on the original management we discovered that the 3.0 bar regulator was actually only holding around 2.5-2.6 bar at WOT according to the inline gauge we fitted. Swapped it over with a spare that I had, and it was holding around 3.1 bar and fuelling looked far more sensible.

 

I recently removed a fpr from an E plate cti and that was a 2.5 bar one. I have known the car for years and it has never been changed.

[Sinbad 16]

Ah thanks for a pic of it working good lol

Hope this sorts the problem.

According to servicebox,there is a 1.9 that runs a 2.5bar reg,strange actually as the lad i bought a 1.6 engine of spares from had this rail spare that he threw in.

It had head gasket failure,im wondering if he ran it oblivious that it was running proper lean and caused the overheat to blow the gasket??

[Baz 421]

My old 1.6 GTi Autocrosser ran for years with a 2.5bar FPR, very well, never knew until it & the fuel rail etc went onto another engine/car and caused havoc until it was realised!

[welshpug 1,657]

1563 A0 NFP

 

PRESS REGULATOR 2,5 BARS -XU9J1

1563 99

 

3 BARS - XU5J

3 BARS - XU5JA

3 BARS - XU9JA

3 BARS - XU9JAZ

 

£100 rrp from Servicebox.

Edited August 30, 2012 by welshpug

[Sinbad 16]

Peugeot quoted me £115+VAT

[Anthony 1,003]

Probably cheaper going through a Bosch service agent directly.

 

The direct fit adjustable regulators (FSE etc) are another option, but you'll need a fuel pressure gauge to set them up initiailly, and they can need periodic adjustment to keep them set correctly given that they can "drift" over time.

[petert 586]

CTi's and Oz spec early GTi were both 105hp DFZ, so that would make sense with 2.5 Bar reg.

[Sandy 191]

FSE adjustable valves are the source of many running issues I've come across, they are highly unpredictable and should not be relied on IMO. I strongly recommend the use of fixed value OE style capsule regs.

[Miles 331 1 Cars]

Yep the 2.5 bar ones are on the low comp 1.9 in the UK, the 122 and 128 models use the 3bar one

 

And Sandy's has a good point about the adjustable one's They do give allot of problems

[Rjuhar 52]

Since I've had my 205 taken apart, resprayed and put back together I have problems with uneven throttle response, lack of power over 4000 rpm and I can't get to the bottom of it. I've bought a new pump but reading this I've found out that it could be a fpr at fault or (even better) not connected properly. Can anybody please explain to me what goes where. Pics would help... Thanks

[hoodygoodwood 70 3 Cars]

Excellent tip this , just checked my spare regulator and the one on my running Miami project , both released excess pressure at exactly 3 bar on my Halfords footpump . Who would of thought the pipe would fit the pump so perfectly - well spotted .

Just need to check the one on my Goodwood and then have a look through the garage to see if I have any more lying around .

Better check the accuracy of the footpump by comparing tyre pressures with my Sykes Pickavant gauge .

Why the connection pipe to the inlet manifold ?

[mrfirepro 127 1 Cars]

I was recently looking for a FPR, if you search on the Bosche number you can find then around £65.

 

Rjuhar - I have some recent pictures, just not downloaded yet, will try and do them tonight and post here.

[Rjuhar 52]

Thanks a million, that would certainly help. Looking fwd.

[mrfirepro 127 1 Cars]

Gregor,

 

A few photos here. My inlet is rebuilt and sat in my kitchen if you need any particular pics.

 

http://s1238.photobucket.com/user/mrfirepro/media/205%20projects/P1020390_666x500.jpeg.html

[Stian_P 1 1 Cars]

Is it necessary to remove the vacuum pipe when testing the fpr?

[petert 586]

Yes, if a 3 Bar reg it should read 3 Bar unplugged and approx. 2.5 Bar plugged. ie fuel pressure minus manifold vacuum.

[Stian_P 1 1 Cars]

Thanks

 

Tested my fpr again to day with the vacuum pipe disconnected, and it dosent seem to hold pressure at all. It releases pressure to fuel tank at 3,1 bar, but the pressure keep decreasing steadily over time. It was down to 1 bar when I disconnected the hose.

 

Is this even possible? Would the car start at all with a non working fpr?