As the original question has been answered,here are my results of fitting the fuel pressure gauge



I have some results

fitted the gauge in between the fuel filter and the rail

primed the system - 2 Bar
turned ignition off then back on to re-prime,gauge needle shoots to 3 then back down to 2.
Ran the car, - 2 Bar
ignition off drops to 1 3/4 bar then increaes to 2 bar within 10-20 seconds

reprime shoots to 3 bar then instantly drops to 2.5 bar
re run engine 2 bar at idle, revved to 3k 2.8 bar

ignition off drops to 1.8 bar rising to 2 bar again within 10-20 seconds

so,do those readings sound normal ?

My main test tho i cant do as i need to fit the tester at night and wait till the morning as thats when the problem is,i need to see if its dropping off from its 2 bar pressure to say 1 bar and re-primin is only making it 1.5 bar etc or something ???

but anyhoo,thougt id do some readings to get a gauge if its o.k

cheers for any input

 

id just speak to a suabru breaker and get one of them or even a subaru tuning company as they will ahve loads of spares which they would have taken of other people cars

 

Cheers

i found this thread on here so it looks like (without removing my old one 1st) this part no. has at least been used on an impreza

https://www.scoobynet.com/general-te...ti.html?nojs=1

 

The Rig,

What year is your car? May have a OE FPR in the garage (used).

Steve

 

Hi,

95 wrx

cheers

 

Not sure if a newage STi one will fit or not?

Steve

 

Hi,
This is the thing, they all look the same, thats what im trying to find out, if they are all the same inside etc, the one i have is from a non turbo but the specs list the legacy turbo and rate it to 3 bar

yet an impreza one has a different part no. but the specs are the same ????

are there any numbers on it ?

cheers

 

Very rare to see a std fuel pressure reg to fail, what's made you think this is at fault?
Usually if it's a pressure issue it's the pump knackered or the filter restricted.

 

agree,but i`m trying to accomodate on the day of things to swap out

the car fires up fine,no problems starting, but when its left overnight or 8hrs+ its starts fine but fires up at say only 300 rpm and takes a few seconds to increase to its correct idle speed (900rpm),if the throttle is left untouched.Its then fine all day,100 starts a day etc,no problems,just when left for 8hrs+

doesnt sound a bad fault, but in the morning it sounds rough as it gradually increase 400 500 600 700 rpm etc,like its only on 2-3 cylinders
due to it starting at such a low RPM (300) or so
leading me onto fuel pressure,i am going to swap the pump out, but was under the impression it would be the FPR letting the fuel pressure drop off,but im confused as if either were at fault, surely it would present itself during the many many starts it gets a day ????

frustrating


cheers

 

Try actually checking the fuel pressure then.

Doesn't sound at all like a fuel pressure issue at this stage though.

Spend the 50 or so quid having it looked at properly instead of throwing random parts at the car in hope of fixing it.
If I am correct, your name rings a bell and you are local.. Why not pop in.

Could be anything from dribbling injectors/seals, dodgy lambda sensor heater, dodgy MAF sensor. MAP sensor or an air leak...

 

o.k,cheers for the input.

i would like to test the pressure but

i dont know where the fuel rail take off adapter is
i dont have the dial/gauge to test it with LOL ha ha

Not sure where to pop into if i am local ?

i only went along the pressure theory as outside temp doesnt make a difference,hot day/night/cold day/night etc and once its fired that 1st time, its sweet ever more until the next 8hr layup

i have a fuel pump to fit anyhoo,mine currently gurgles more than whines when it primes, so will do that and go from there

cheers

 

Thinking it might have been Rigster that was local (gloucestershire).
Never mind.
See what you find with the pump then.
Get a gauge and T into the pressure pipe straight out the top of the fuel filter on the left hand wing. (the hose between filter and rail)

 

i have a spare standard FPR for a 95 wrx , if your still looking for one

 

o.k,might ty that,get one of these

http://cgi.ebay.co.uk/FUEL-PRESSURE-...item3a5ce2cc1c

so i T into the main fuel delivery line (8mm) from the filter to the injector rail ?

i am in gloucestershire too :-)

cheers for your help

 

Perfect.. Yes, correct pipe.

 

I have some results

fitted the gauge in between the fuel filter and the rail

primed the system - 2 Bar
turned ignition off then back on to re-prime,gauge needle shoots to 3 then back down to 2.
Ran the car, - 2 Bar
ignition off drops to 1 3/4 bar then increaes to 2 bar within 10-20 seconds

reprime shoots to 3 bar then instantly drops to 2.5 bar
re run engine 2 bar at idle, revved to 3k 2.8 bar

ignition off drops to 1.8 bar rising to 2 bar again within 10-20 seconds

so,do those readings sound normal ?

My main test tho i cant do as i need to fit the tester at night and wait till the morning as thats when the problem is,i need to see if its dropping off from its 2 bar pressure to say 1 bar and re-primin is only making it 1.5 bar etc or something ???

but anyhoo,thougt id do some readings to get a gauge if its o.k

cheers for any input

 

let car idle, allow pressure to drop to the lower figure (this is the pump going into reduced voltage mode)

apply pressure to back of FPR (via vac hose) fuel pressure should rise and stay there as long as you have pressure on the back of the FPR
Assuming there is no loss of pressure on the FPR and assuming actual fuel pressure remain constant during this test.
Result = nowt wrong with FPR.

You deleted the original post so can't remember what the actual probelm was, only your "findings"

 

cheers

i just did that,had to do it quickly,so the car was started from cold, as the missus has took the car out,the reading was 2 bar,i put pressure on the vac pipe of the FPR,no change in reading,still remained at 2 bar

i removed the vac pipe whilst the engine was running, it shot to 3 bar and idle increased slightly,put vac pipe back on,2 bar,applied pressure,still 2 bar (it was hard to squeeze the pipe totally as its quite stiff but still,even with some pressure,no change in reading)

 

Sounds ok to me, doing what its supposed to.

What sort of pressure did you apply?

 

i just used my fingers to try n crimp the pipe,like i was squishing a flea LOL,it was quite a solid pipe,maybe pliers would of been better but i didnt have time, i did squash it a bit but no reading change

 

When on idle its under vacuum hence the low fuel pressure (as idle speed varies so will the pressure) . If you apply 1 bar pressure your fuel pressure will rise to 4 bar (assuming 3 bar static)

 

Hahaha this is the trouble with diagnosis via internet.

By applying pressure I meant with a bloody pump.. Increase the pressure in the pipe to say 1 bar.. Not squeeze the damn thing < insert faceplam here >

Never mind, pulling it off and putting it back on again pretty much says it's working fine.
Forget it, it's not the issue.

 

 

Rig,the readings you have on the guage matches what mine reads too.

i believe it shoots to 3bar during the prime time is normal and mine also holds pressure as yours does too.

overnight the pressure in the line does fall but the fuel is simply returning back to the tank.i may stand corrected tho