C70 S70 V70: Fuel pressure

[LANGEN6]

Fuel filter blown off Volvo v70 D5 163

Broke down on way home car just cut out, AA came out and found fuel filter O ring to be hanging out ( just to front of rear wheel)
Took filter off and reseated, when cranking car over the filter housing was blown off. Got it home fitted new filter and refitted housing . Started cranking car and again blew filter housing off. Asked at local Volvo when picking filter up, they have never had fault. Some how the high pressure system is leaking back and pressurising the low side, would appreciate any feedback

[LANGEN6]

No one could throw any light on this problem , checked with fuel Injection specialists, their advice was a possible blockage on return line.

Found fault to be in tank pump creating too much pressure, had to drop tank down to access filter housing retaining bolts, checked fuel pressure created from pump and compared with good pump. Normal pressure was 20psi whilst original pump created 120psi. Replaced pump and fitted replacement filter housing all ok

[Bernard333]

The in tank pump should produce approx 29psi max on a D5 at the pump body outlet , by the time the fuel reaches the inlet to the engine mounted pump the pressure is way below this level . I am now on pump no 4 in my 2003 D5 , its been the only major failure on the car in 160000 miles . How a D5 Bosch pump could produce 120psi is beyond me but I take your word for it . The pump I am using at the moment was taken from a T5 and produces 55psi maximum , the rest of the D5 fuelling system copes easily with this pressure with no ill effects , it been in place since January . I am puzzled as to how your problem can happen , I would have said replacing the in tank pump would not have solved it but clearly its worked for you . If you believe the actual metal canister Bosch pump rather than a blockage caused the problem I would flag this up directly with Bosch as it seems like a first to me . The leak back from the injectors is sent back to the tank along with excess fuel from the low pressure side of the engine mounted pump , its normally not under much pressure but when I measured the flow rate it was several gallons an hour on mine (this is normal) , it goes straight back to the tank and not via the fuel filter first . A solid blockage in the fuel return line could maybe cause excess pressure to reflect back through the injection pump to the fuel filter ? But if that were the case you would still have the problem .

[gooien]

Originally Posted by Bernard333

The in tank pump should produce approx 29psi max on a D5 at the pump body outlet , by the time the fuel reaches the inlet to the engine mounted pump the pressure is way below this level . I am now on pump no 4 in my 2003 D5 , its been the only major failure on the car in 160000 miles . How a D5 Bosch pump could produce 120psi is beyond me but I take your word for it . The pump I am using at the moment was taken from a T5 and produces 55psi maximum , the rest of the D5 fuelling system copes easily with this pressure with no ill effects , it been in place since January . I am puzzled as to how your problem can happen , I would have said replacing the in tank pump would not have solved it but clearly its worked for you . If you believe the actual metal canister Bosch pump rather than a blockage caused the problem I would flag this up directly with Bosch as it seems like a first to me . The leak back from the injectors is sent back to the tank along with excess fuel from the low pressure side of the engine mounted pump , its normally not under much pressure but when I measured the flow rate it was several gallons an hour on mine (this is normal) , it goes straight back to the tank and not via the fuel filter first . A solid blockage in the fuel return line could maybe cause excess pressure to reflect back through the injection pump to the fuel filter ? But if that were the case you would still have the problem .

Hello all. I have exactly the same problem on my car this weekend. Filter housing was blown off when the car was running on idle. Could not find any fault with threads, or why this happend. I reinstalled fuel filter and housing, and started car again. It blew off again(this time the treads is the housing cracked), i checked return line from engine to tank, this is not blocked (i can hear the diesel bubbels when blowing). I installed a pressure gage out from pump (connector into filter). And reading was 110psi. This is 4 times higher than i expected. So i suppose the fuel pump must be faulty, but i cant see why it shall build up this pressure. Nobody i have talked to in Norway has had this problem. So now i have to replace pump and filter housing.. Hmmm.

[gooien]

Originally Posted by gooien

Hello all. I have exactly the same problem on my car this weekend. Filter housing was blown off when the car was running on idle. Could not find any fault with threads, or why this happend. I reinstalled fuel filter and housing, and started car again. It blew off again(this time the treads is the housing cracked), i checked return line from engine to tank, this is not blocked (i can hear the diesel bubbels when blowing). I installed a pressure gage out from pump (connector into filter). And reading was 110psi. This is 4 times higher than i expected. So i suppose the fuel pump must be faulty, but i cant see why it shall build up this pressure. Nobody i have talked to in Norway has had this problem. So now i have to replace pump and filter housing.. Hmmm.

Ref above. Car is a v70 2006 2.4diesel. And i am talking about the pump inside the diesel tank.