Hi, I have a 04 S60R and I have this really bad stumble under hard acceleration at about 3500-4000rpm. I've replaced the MAF, Fuel pump, PEM, TVC, fuel filter, and FPS. Car idles fine, but when monitoring the fuel pressure it drops from about 400kpa to 150-200kpa when under acceleration(at roughly 4k rpm). I am stuck at what could be causing this to do that.
It did used to drop fuel pressure at idle, after running for about 10min, it would just drop to about 130-150kpa fuel pressure( verified by fuel pressure gauge hooked to the rail).

Does anyone have an insight as to what could be causing this to drop fuel pressure like that?

 

Hi. Did you change whole fuel pump assembly or pump only

 

I changed the whole pump/sender assembly, ordered one from volvo since we couldn't find a "R" pump aftermarket.

 

It is also back to dropping the fuel pressure after idling for a while. We took it for a drive today to warm it up (5min roughly) then let it idle for another 5-7 min. The fuel pressure would drop about 10psi then shoot back up, then slowly fall, then shoot back up. Then it eventually just dropped too low and the car quit.

 

any fault codes? i had same kind of symptoms after fuel pump change when my in tank fuel filter was clogged. have you checked wiring from pem to pump?

 

just a fuel pressure code. signal too low. we have checked the wiring. all is good, no corrosion or resistance.

 

Hello!

Any update there?
I'm suffering in the same...

 

Apparently the fuel pump we put in(new from volvo) was defective. Needed a new pump