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Mechanical loading- tight Alternator, A/C compressor - had that myself; A/C still worked but put a hell of a load on the engine and burnt the aux belt.

It is not just the mechanical load - it pull s the battery down as well on starting, even thought it is a new battery.

You could just slip the belts off and check!
 

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Mechanical loading- tight Alternator, A/C compressor - had that myself; A/C still worked but put a hell of a load on the engine and burnt the aux belt.

It is not just the mechanical load - it pull s the battery down as well on starting, even thought it is a new battery.

You could just slip the belts off and check!
Clearly you've never changed a serpentine belt on the 3.2 JTS. smh

To the OP .. if you revisit post #24 where you provided a plot of fuel pressure vs rpm, you'll find the devil is in the details(personally had to adjust monitor brightness to see), the major reason I like to export data into a spreadsheet. Anyway.
From ignition on @ about 8:27:30 you're only reading about 250 Kpa - this is what your intank fuel pump is delivering before cranking. By specs should be delivering 600 Kpa - 6 Bar or thereabouts. It's a tad confusing that the intank fuel pump has been deemed as operating to specification. Its not what this plot is showing.

Given that all the plots provided are showing accurate fuel pressure readings with engine running ie. 5500+Kpa Cold start, 3000KPa idle warm engine then its safe to conclude the fuel pressure sensor is a.o.k as is the HP pump and your diagnostic software is up to the task as such you can dispense with using a dedicated fuel pressure gauge. So an easy test for you to perform would be to remove the fuel pump relay/fuse before hooking up diagnostics/ignition on, read the fuel pressure, should be zero on cold start - insert relay/fuse - should now be reading ~600 Kpa.
 

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Clearly you've never changed a serpentine belt on the 3.2 JTS. smh

To the OP .. if you revisit post #24 where you provided a plot of fuel pressure vs rpm, you'll find the devil is in the details(personally had to adjust monitor brightness to see), the major reason I like to export data into a spreadsheet. Anyway.
From ignition on @ about 8:27:30 you're only reading about 250 Kpa - this is what your intank fuel pump is delivering before cranking. By specs should be delivering 600 Kpa - 6 Bar or thereabouts. It's a tad confusing that the intank fuel pump has been deemed as operating to specification. Its not what this plot is showing.

Given that all the plots provided are showing accurate fuel pressure readings with engine running ie. 5500+Kpa Cold start, 3000KPa idle warm engine then its safe to conclude the fuel pressure sensor is a.o.k as is the HP pump and your diagnostic software is up to the task as such you can dispense with using a dedicated fuel pressure gauge. So an easy test for you to perform would be to remove the fuel pump relay/fuse before hooking up diagnostics/ignition on, read the fuel pressure, should be zero on cold start - insert relay/fuse - the new reading should be you base reading + 600 Kpa.
”Clearly you've never changed a serpentine belt on the 3.2 JTS. smh”.

No! I cut it off my 159 engine which had failed. It got the engine running - sufficient to confirm the compressor had seized.

As the engine was being replaced by my rebuilt Brera, it didn’t matter, other than to prompt me to to buy a new compressor.
 

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Discussion Starter · #85 · (Edited)
Clearly you've never changed a serpentine belt on the 3.2 JTS. smh

To the OP .. if you revisit post #24 where you provided a plot of fuel pressure vs rpm, you'll find the devil is in the details(personally had to adjust monitor brightness to see), the major reason I like to export data into a spreadsheet. Anyway.
From ignition on @ about 8:27:30 you're only reading about 250 Kpa - this is what your intank fuel pump is delivering before cranking. By specs should be delivering 600 Kpa - 6 Bar or thereabouts. It's a tad confusing that the intank fuel pump has been deemed as operating to specification. Its not what this plot is showing.

Given that all the plots provided are showing accurate fuel pressure readings with engine running ie. 5500+Kpa Cold start, 3000KPa idle warm engine then its safe to conclude the fuel pressure sensor is a.o.k as is the HP pump and your diagnostic software is up to the task as such you can dispense with using a dedicated fuel pressure gauge. So an easy test for you to perform would be to remove the fuel pump relay/fuse before hooking up diagnostics/ignition on, read the fuel pressure, should be zero on cold start - insert relay/fuse - the new reading should be you base reading + 600 Kpa.
That plot was not a cold start. The below image is cold crank and is depicting the engine cranking for a couple of seconds before building up enough pressure in the fuel rail to actually start the engine. Or at least that is how I interpret the info. I managed to download the plot on a CSV, should you be interested in having a look. I will test your suggestion tomorrow and report the findings.
Screenshot_20210720-200637.jpg
 

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~08:27:30, ignition on. Surely the in-tank pump is not expected to hold working pressure indefinitely, when the engine is switched off.

But, it is a question of how long it takes to reach working pressure? Assuming the pump is good, this must therefore be down to any pressure regulating device - is it being relieved, and terminal voltage of the battery.

8:28:20, and a bit - the starter motor cranks the engine and the Alternator begins to produce an output.

Virtually at the same time the in-tank pressure rises swiftly, the engine “Strikes”, idle rpm settles quickly and the pump pressure settles to the correct value - yes/no?

I could be barking up the wrong tree but, it suggest two things to me:-

1.) Initially, whilst the engine is off, the pump is relieved of pressure, which should stop as soon as the ignition is switched - to enable the pump to “Prime” the High Pressure Pump. However, there is a delay, which may be a function of low voltage on the relief valve - not closing until the Alternator spins and lifts the terminal voltage across the relay!

2.) There is a problem with Alternator/Battery regulation, which is only overcome when the engine is running and the alternator is giving an output.

This plot suggests to me, the problem lies with the Pre-ignition phase. Relatively speaking, this is at a point where battery voltage is lowest (not being supported by alternator output current) and any “High Impedance/corrosion/poor earth return or supply connector”, would have greatest impact upon the in - tank terminal voltage.

Corroded connections can form semi-conductor junctions. Semi-conductor junctions have internal “PD” across them which are Opposite Polarity to the supply voltage.

This can cause a reduction of terminal voltage seen by control circuits; at a time when a system is drawing low current, until such time as Supply voltage and current is sufficient to overcome it.
 

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If the engine is cranking the High pressure pump is operating hence building fuel rail pressure. Problem as i see it - the intank pump cannot provide enough flow to support the high pressure pump. Looking at the latest plot, the engine is cranking a while at 200 rpm with fuel pressure increasing(HP pump), its not until fuel pressure gets over 500Kpa @ 350rpm that the engine starts.

Also, with ignition off fuel rail pressure should not drop more than 0.3 Bar over a minute(according to the alfa bible). Intank fuel pump specced for 5.7 - 6.3 Bar.

Sure, ignition on, intank pump should be getting battery voltage naturally there is a relay operating between the two which could have a pitted contactor affecting supply voltage to the intank pump. Or as mentioned corroded connectors. Or simply a fuel pump on its way out. Or a fuel leak in the system(this includes injectors) which ultimately leads to reduced fuel rail pressure.
 

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Discussion Starter · #88 ·
Also, with ignition off fuel rail pressure should not drop more than 0.3 Bar over a minute(according to the alfa bible). Intank fuel pump specced for 5.7 - 6.3 Bar.
Thats the drop in pressure in the rail after ignition off. I totally agree with you on your review on the situation. I now have to go eliminating possible causes until the issue is resolved.
Screenshot_20210721-172434.jpg
 

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What exactly are you saying? - you may be OCD, but that does not mean you have to reduce everyone else to it!

Tell it as it is, explain your understanding and clear up any ambiguity between yourself and those trying to help.

Given how little you, and indeed all of us know about these cars, and the way they work, things will not get better unless knowledge, or lack thereof is shared.
 

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Discussion Starter · #90 · (Edited)
Brian, while I understand your desire to learn new things about the 3.2 JTS, I have to remind you that I am a father of two and I barely manage to squeeze in 5 mins to share a brief post here. Unlike you, I am no engineer! I am just a petrolhead with lots of love for Alfa. I have learned a lot here and I created the thread precisely because there ain't a lot of info on the 3.2 and all its gremlins. So far I tested a few hypothesis and none seemed to solve the conundrum. As I see it, for some reason the car is struggling to build up pressure in the fuel rail quickly enough on cold starts. At times it is also a bit slow to react on harsh acceleration with downshift after cruising on 5th ot 6th gear on lowish RPMs. From what was said, I believe that the pump is holding pressure long enough after ignition off. Doesn't have any visible leaks,that is confirmed. The only possibility of leak is with the injector(s), but that is hard to confirm without uninstalling all of them and testing. Your AC theory seems unplausable in my case, since no deterioration in MPG is observed and one would suggest that it would affect much more than cold starts. Alternator is working well and this was also tested. Battery is brand new. Fuse seems OK. MAF and coolant temperature sensor were tested to no avail. So, IMHO, its either, injectors, pump going bad, or bosch plugs not being genuine,ooor some electricalgremlin preventing the pump from operating properly on cold start. IDK.
 

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IVO, sorry for letting my frustration get the better of me and yes, I appreciate it isn’t that easy with everything else going on in the “Real World”.

True, it is difficult to eliminate issues as everything, bar nothing is so interconnected with these engines.

However, chasing ghosts can be very expensive - particularly with the 3.2 JTS. So it is particularly important, to have more than a suspicion about any components, before swapping them out.

But, as much understanding of what it is not, is needed to eliminate things from the equation. I just don’t think you are any closer to that than at the outset. It is easier sometimes to prove what it is not, than what it is. But at some point, more than casual suspicion has to develop into firm belief.

That won’t happen however, unless individual elements are focused on to the point that they can be eliminated from the equation, or otherwise.

If economy is still as expected, it should theoretically eliminate the HP pump and by the same token, the LP pump. But it doesn’t discount the likelihood it is associated with the initial start-up process of the LP pump.
 

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Ivo, how many miles has your engine covered? Like you I am an Alfa lover. I defer to those with greater engineering knowledge. If you can afford for the car to be off the road for a short while I would encourage you to injector refurbishment. Minimally you could remove one injector rail and examine the injectors on one bank. I wish I had taken pictures and will do so for anything else that might be of use to others. Mine were heavily varnished and gummed. Regarding fuel economy it might be hard to detect if you've owned the car for a long time and injector degrading in efficiency has taken place over time. Would be also hard to compare Brera to 159 due to weight and driving differences. I typically found I would achieve 23mpg. Now with injectors cleaned and an extra 22cc flow per minute it is now about 25 mpg. That same drop in pressure after shut down could be explained by faulty injector solenoids which could also account for the low pressure during start up if the injectors are leaking?
 

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After seeing this last plot I've got my money on a partially stuck open return fuel shutoff solenoid. If you follow the front most fuel line from the Hp pump(return line) you'll see it attached to a solenoid/valve and latter to the return line back to fuel tank. Its function is to prevent a pressure drop in the system when the engine is stopped.When the engine is running the solenoid/valve is opened to allow fuel return to tank.
So if it's partially stuck open you wont get adequate LP fuel to start engine(when solenoid should be closed) due to it leaking back to the tank and on shutdown when it is again closed to hold pressure in the system.

Some information for comparative purposes. I primed the fuel system with ignition on, pulled the fuel pump relay and tested for pressure drop.

87 psi was maintained for 10 minutes then dropped to 55 Psi and slowly dropped to 50 psi over the next 5 minutes.

I've got no idea how you can test for a partially open valve but can tell you it takes battery voltage to operate.

edit: i guess you could always plugged this outlet at the HP pump and check your fuel rail pressure with ignition on.
 

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Quote Petromet:- “When the engine is running the solenoid/valve is opened to allow fuel return to tank”.

From the above quote, it is safe to say the solenoid valve is “Relaxed” - de-energised when the engine is off. If the valve has closed properly, pressure down-stream of the valve should fall to zero? and flow cease.

Switching off the engine and “cracking open” the down-stream line one ought to see if it is “Weeping”.
 

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well come to think of it .. disconnecting the return line at the quick dis/connect connector to see if there is leakage past the solenoid would do the trick too. What's important we don't want see any leakage other than what's in the short line from solenoid/ valve to connector.

Edit: Just had a quick look, you would need to disonnect the hose from the solenoid outlet and simply run a temporary hose to a suitable container.
 

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well come to think of it .. disconnecting the return line at the quick dis/connect connector to see if there is leakage past the solenoid would do the trick too. What's important we don't want see any leakage other than what's in the short line from solenoid/ valve to connector.

Edit: Just had a quick look, you would need to disonnect the hose from the solenoid outlet and simply run a temporary hose to a suitable container.
“And Don’t Start the Engine”!!!!!!!!!!
 

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this test was performed and no issues were found...
Over the years, I have changed four or five in-tank pumps on 3.2jts cars, which may not seem like many but considering the number of these cars on the road, it is relatively high.
How exactly did they test the pump? If they turned the ignition on, or started the car (to move it into the workshop for example) then testing it immediately afterwards would be pointless. Ideally connect a gauge, start the car and make sure everything is ok, then leave it overnight. Check the pressure in the morning (without starting or turning the ignition on) and the observe the gauge reading as you attempt to start the engine.
I assume that you have already checked the relay and its connectors (in the fusebox), as this was quite a common issue when these cars first came out (the relay would overheat and melt the fusebox).
 

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Why not start the engine ..just plug the removed line.

I'm one of those statistics of having to change the in tank fuel pump. Unrelated to poor flow, @ 50K km's it had developed a hairline crack to the housing of the outlet channel, allowing fuel to slowly leak with a lovely cabin aroma to follow.
 

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Why not start the engine ..just plug the removed line.

I'm one of those statistics of having to change the in tank fuel pump. Unrelated to poor flow, @ 50K km's it had developed a hairline crack to the housing of the outlet channel, allowing fuel to slowly leak with a lovely cabin aroma to follow.
Whichever is easiest. Could check for Zero Volts across the solenoid valve when the engine is switched off!

However, not discounting LP pump, It is a lot quicker and simpler to check the solenoid to elimiate it from the equation.
 

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Discussion Starter · #100 ·
guys, currently I am out of town..on some sort of vacation, visiting the in laws at the seaside. Therefore I will postpone all further checks for when I am back in civilization. However, I would like to point out that the fusebox is ok. Also there is no visible leakage,nor smell of gasoline. I wanted that ruled out,since I have 2 kids and a Golden retriever at the back. What would you recommend? Checking 1st the solenoid, then the pump itself and ultimately the injectors? Hypothetically, if an injector is leaking, how would the symptoms differ from those of a bad solenoid?
 
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