General Fuel rail pressure testing.

[murfman53]

Hi to all,

The car is a 2004 panda 1.2 with 90k miles on it.

The problem is at higher rpm the engine struggles to go faster. Like fuel

starvation. I'd like to do a fuel rail pressure test.

I see there is a schrader valve ( I believe its called ) at the end of the

fuel rail.

I removed the plastic cap on top, now I need to screw in a connector or

adapter into the schrader valve. The inside diameter is around 8mm.

Is there any place that would have this adapter instead of buying the

whole fuel pressure test kit.

Thanks a million.

John.

 

[g8rpi]

Hi to all,

The car is a 2004 panda 1.2 with 90k miles on it.

The problem is at higher rpm the engine struggles to go faster. Like fuel

starvation. I'd like to do a fuel rail pressure test.

I see there is a schrader valve ( I believe its called ) at the end of the

fuel rail.

I removed the plastic cap on top, now I need to screw in a connector or

adapter into the schrader valve. The inside diameter is around 8mm.

Is there any place that would have this adapter instead of buying the

whole fuel pressure test kit.

Thanks a million.

John.

Hi,
A Schrader valve (same as fitted to tyres) is normally coupled by the threads on the outside. The Panda uses a quick release coupling with a Schrader insert. You need the proper coupler that fits the outside, not someting that screws inside. The only thing that might fit is an airconditioning coupler but the seals may be damaged by petrol. get a garage to check it or buy a chep kit off ebay.

Robert G8RPI.

 

[koalar]

Should be able to indirectly see if it fuel starvation by logging the upstream O2 sensor.

As it leans out there should be a lower voltage from the O2 sensor


Not saying that this is the problem. A few people have had a problem reving. As they have pressed the accelerator it get to a point and the drops down again. This has been a faulty crank sensor. The quality of the signal is not good enough and the ECU gets confused

 

[murfman53]

Hi,
A Schrader valve (same as fitted to tyres) is normally coupled by the threads on the outside. The Panda uses a quick release coupling with a Schrader insert. You need the proper coupler that fits the outside, not someting that screws inside. The only thing that might fit is an airconditioning coupler but the seals may be damaged by petrol. get a garage to check it or buy a chep kit off ebay.

Robert G8RPI.

Hi,

As you say, I need the proper coupler that fits the outside, and not something that screws inside. I'll see what i can find off ebay.
Thanks a million.
John.

 

[murfman53]

Should be able to indirectly see if it fuel starvation by logging the upstream O2 sensor.

As it leans out there should be a lower voltage from the O2 sensor


Not saying that this is the problem. A few people have had a problem reving. As they have pressed the accelerator it get to a point and the drops down again. This has been a faulty crank sensor. The quality of the signal is not good enough and the ECU gets confused

Hi,

I've checked the upstream 02 sensor, and checked the short and long term

fuel trims, and the result is that its running on the lean side. Used a smoke

machine to see if any vacuum leaks, but all is good.............no leaks.

My logic is either too much air (which doesn't appear to be the case)

or, not enough fuel to injectors ( hence, my interest in checking fuel rail

pressure). Never considered the signal quality to the ecu from the crank

sensor.

Thanks for your reply.

John.

 

[Goudrons]

As it leans out there should be a lower voltage from the O2 sensor

Higher voltage.

It's the heat that causes the sensor to generate a small voltage.
The leaner the engine, the hotter the exhaust gas, so the voltage of the O2 sensor rises.

A car in good order will average out a reading of 0.45v or there abouts. (they peak and trough 0.9 and 0.1V about once a second at idle)
Lean the mix out and it increases, enrichen it and it drops.

But

Overall fuel status will cause it appear to be running the opposite (confusing I know).
It'll be trying to dump extra fuel in to compensate for the lean signal and take fuel away to lean out a rich signal, so the fuel trims are reverse.

Before diving in the deep end, swap the O2 sensors over, they are both the same.
I've had a duff O2 in the past and it caused similar issues and it didn't cause a DTC.

 

[koalar]

https://www.fiatforum.com/panda/448396-wont-rev-past-2-5k-now-wont-start-2.html

 

[murfman53]

Higher voltage.

It's the heat that causes the sensor to generate a small voltage.
The leaner the engine, the hotter the exhaust gas, so the voltage of the O2 sensor rises.

A car in good order will average out a reading of 0.45v or there abouts. (they peak and trough 0.9 and 0.1V about once a second at idle)
Lean the mix out and it increases, enrichen it and it drops.

But

Overall fuel status will cause it appear to be running the opposite (confusing I know).
It'll be trying to dump extra fuel in to compensate for the lean signal and take fuel away to lean out a rich signal, so the fuel trims are reverse.

Before diving in the deep end, swap the O2 sensors over, they are both the same.
I've had a duff O2 in the past and it caused similar issues and it didn't cause a DTC.

I was thinking along those lines, and I replaced the 02 sensor. It made

alittle difference, but didn't cure the problem. I'm convinced its a lack of

fuel is my issue, I could be wrong, but a fuel rail pressure test will tell me

one way or the other. My long term fuel trims are at 69!!!! So with these

type of figures its something fairly major.

John.

 

[murfman53]

https://www.fiatforum.com/panda/448396-wont-rev-past-2-5k-now-wont-start-2.html

Thanks for this link. Interesting read alright. This car too has a square oil cap.

The systems I have would be slightly different in that I can reach higher rpms

but I must not overlook the crank positioning sensor.

John.

 

[murfman53]

The Latest,

I finally concocked a connection to the schrader valve on the fuel rail.

Rigged up the pressure gauge, then switched on the ignition.

The dial went to..............18 psi. And when the petrol pump motor finished its

cycle ( about 3 seconds ), and switched off, the dial on the pressure gauge returned

to zero immediately.

Firstly,I'm not sure of the panda fuel pressure spec, but 18psi seems very low, when

considering earlier punto fire engines were at and around 40-45 psi.

Secondly, once the pump switches off the pressure should remain there for sometime.

Is there a check valve in place along the input line, or in the petrol tank somewhere.

I honestly don't know to be honest.

Should I consider the pump motor has had it, and get another one instead.

I may have stuck open injectors, which might account for poor fuel consumption.

If I have to buy a petrol pump motor, is it possible to purchase the motor only.

John.

 

[koalar]

Info here

 

[murfman53]

Info here

Thanks for the info. Looks like all the interesting devices are located in the

tank.

You wouldn't happen to know the operating fuel rail pressure?

I suspect between 40 to 45 psi. Not 18 psi which this car shows.

The pressure regulator looks like one of the goodies in the tank.

If I knew the proper pressure then I'd know my next step.

The punto is basically the same engine, must have a look over there.

Keep looking.............name of the game!

John.

 

[koalar]

3.5 bar

 

[murfman53]

3.5 bar

Thanks for the info koalar.

Looks like the issue is with the pump seen better days. My guess would be that

its unable to hold pressure at all, because of contamination to the pressure

regulator or its non functioning.

At 3.5 bar (50 psi), is a big difference to the actual reading of 18 psi

(1.24 bar).

Whip out the pump tomorrow, and get a closer look at it in detail.

Again, thanks koalar for the info, much appreciated.

I'll keep all up to date on the progress.

John.

 

[murfman53]

Hi,

The latest,

Removed the fuel pump relatively easy enough, although the outer locking ring was

tricky but came loose after a little patience. Must make up a plywood outer ring

template with notches cut out on the inner diameter, so when its time to put back

in place the template will make tightening process easier.

https://www.ebay.ie/itm/173041704720?ViewItem=&item=173041704720

I came across this fuel pump, not an original, an after market, but that doesn't worry

me at all. Comes with a 2 year Warranty. The one I took off the car is a carbon copy.

Second hand ones here, if you're lucky enough finding one is selling between 70-85

euros. Apparently, its a common fault on the panda......fuel pump fails. I'll wait until

it arrives, put it in place, check fuel pressure, and run it for a week. If all is ok, I'll

get another one, as I drive a 2007 1.2 skydome panda myself. At that price you can't

go wrong.

 

[varesecrazy]

I tried rigging up a spanner to undo the nylon ring nut.. failed miserably..
upon seeing the guide in the punto section I realised I should've depressurised it 1st..


got a punto one undone ok once I knew.

 

[murfman53]

Hi,

I know where you are coming from alright. My biggest problem was adapting my fuel

pressure gauge hose connections to the fuel rail schrader port connection. I bought

this set

http://www.ige.ie/fuel-pressure-test-kit/

Unfortunately it works great for GM/Chrysler cars................not designed for Fiat.

Not until I got my hands on it. With the aid of a schrader valve removal tool, cut to

length of 50mm approx. I then used one of the fittings in the above set, and hey

presto, clicked on my pressure gauge and ready to go. It'll be part of the set now.

John

 

[murfman53]

Hi,

I also bought this set

http://www.ige.ie/12v-fuel-injector-tester/

It'll be useful to check flow rate from each injector,against pressure loss, and give me an indication if any

of the injectors are dirty/blocked and need cleaning.

John.

 

[murfman53]

The Latest news.

Took delivery of the new fuel pump during the week, and looks the biz.

Installed it into the tank, connected up the fuel pipe and wiring connector.

Rigged up the fuel pressure gauge to the fuel rail, and switched on the ignition

hey presto..................52psi. Lovely Jubbly.

Then one by one I disconnected each injector plug and placed the new injector pulse

reader in its place. And checked each in turn. I used Pulse 1 on all the injectors,

and the 4 of them went down to 47 psi. Happy with result, when they are all the same,

connected up the diagnostic tool to see the short and long term fuel trims readings. Up to now,

the readings were adding fuel all the time, now live data are taking away fuel and almost at

normal at up to 8%. Then I took the car for a spin........................and as my brother says

Drive it as if you stole it!!! I hit 80mph..................going up hill!!! Like a bullet now, no hesitation

throughout rpm range, smooth all the way. Checked live data with multiecuscan on normal run

the injector pid. Gave a reading of between 2.2 to 2.7, where before it was reading 4.6 and

more at times practically double.

The pressure gauge and the injector pulse reader were absolutely great to check everything

after the installation. With these two devices used together its very quick to know how your

injectors are performing, and if one is reading different from the other 3 then you can suspect

it straight away. I could have coarse removed the fuel rail with injectors still connected to it

and used the devices together and visually see the spray pattern each injector emitted from its

nozzle................but I went the lazy route.

When I get my own 2007 Panda back................I'll run a check on it just to make sure all

is as it should be.

John.

 

[Wee Smurf]

Those checks all sound good to me. I could lend you my Multijet...