s60 t5 2006 stalling

volvomadness · Post by **volvomadness** » 28 Jun 2021, 18:22

On initial start the idle jumps around and then finally settled down. Can Drive the car then with no problem
After it sits for a while when started and i take off it will stall out (especially if AC is on), starts right up. I have to let it run for a few minutes before I take off and then no problem. NO CEL

Replaced fuel pressure sensor, plugs, fuel filter, cleaned MAF, still have the problem

I suspect I am losing fuel pump pressure. Also the gauge sometimes doesn't register correctly.

Replacing a fuel pump is fairly expensive so I want to make sure its that.

Question:
If I disconnect the wires to the fuel pressure sensor and the problem goes away does that mean its the fuel pump.
Question :
If I connect a fuel pressure gauge to the schrader valve and test before I start (with ignition on) what should the pressure read 40psi?

Any Thoughts would be appreciated.
Madness

Post by **xHeart** » 28 Jun 2021, 18:28

Is the check engine light (CEL) on, if so, you may want the error code read at a place like O'Reily.

volvomadness · Post by **volvomadness** » 28 Jun 2021, 18:32

NO CEL

volvomadness · Post by **volvomadness** » 28 Jun 2021, 18:32

I Have a scanner

Post by **cn90** » 28 Jun 2021, 22:54

I wrote a Throttle Body cleaning in XC90 forum.
You can do it w/o removing the manifold.

EngineeringBloke · Post by **EngineeringBloke** » 29 Jun 2021, 09:12

Fuel pressure should be around 55 PSI.

Mine starts out at that and then drops to 43 PSI after a few seconds (30 seconds or so and/or after I start to move). I see that on the Torque app and also confirmed it with a loaned fuel gauge from an auto parts store. I think pressure dropped when the ignition and fuel pump were off - the system should be holding pressure, so this is suggestive of a fuel system leak.

My main symptom is poorer than expected MPG (16 - 18 local) and a hot top of engine. I also see the measured A/F ratio rise from 14:1 to 28:1 when I take my foot off the accelerator. This is a lean mix which could account for the hot engine but may be unrelated to the MPG issue.

I replaced front O2 sensor, PEM, FPS, and fuel filter. (Plus plugs, new MAF, and new after-market throttle body).

I suspect that the CEM is setting a lower pressure in response to a problem in fuel air management.

I am going to try replacing fuel injectors as if one is leaking then extra fuel could get into the engine. I have new injectors, ignition coils and a VIDA/DICE unit, but I want to get the latter working first to see if I can find a code or bad module - no CEL at the moment.

My throttle plate never closes below 11%, although I did replace the throttle body with an after market one - no change. Perhaps extra air needed to balance leaking fuel?

I have a couple of days off soon and plan to work on DICE, injectors and coils.

Edit - corrected some typos and added fuel pressure loss after turning off car. Corrected A/F ratios.

jkatz · Post by **jkatz** » 30 Jun 2021, 15:06

I suspect that the CEM is setting a lower pressure in response to a problem in fuel air management.

I am going to try replacing fuel injectors as if one is leaking then extra fuel could get into the engine.

I replaced my fuel pump, then later I replaced all 5 injectors, of which one leaked all the time and at least one other must have been leaking a little.

With the new pump I was maintaining 55 psi at the sensor while driving, but I was experiencing hard hot starts. Fuel pump duty cycle at idle/low speed was about 54%.

After replacing the injectors it is easy to start every time and fuel pump duty cycle dropped to 46% at idle/low speed.

I think you both should watch the pump duty cycle and fuel pressure while on a test drive. You want to see if your CEM is telling the pump to run, and if the pump is responding by maintaining pressure.

EngineeringBloke · Post by **EngineeringBloke** » 30 Jun 2021, 15:55

Yes, thanks for your post. It is the inspiration to replace my injectors.