V70 D5 sudden power power loss

[Bernard333]

125k miles and now having problems , replaced failed diesel lift pump with a Denso pump from a 2000 Toyota ( its fits exactly into the Volvo/ Bosch plastic brackets and filter , all the pipes were able to fit and measured pressure is 2 Bar same as original Volvo but cost £10 instead of the £250 quoted by Volvo ). Car is still having problems , when tank gets less than 70%full car will not start and ' Urgent Engine System Service' comes on . Pipes in fuel tank are all in correct place and reaching the bottom of the tank. Second problem is that when trying to accelerate hard the same ' Urgent Engine System Service ' message comes up and loss of power ensues which can be restored by turning off the ignition and back on again . Under normal driving conditions everything seems ok and fuel consumption is fine at 50mpg +. Local mechanic used engine diagnostic on the engine and says there is no problem from the engine forwards , the engine mounted low and high pressure pumps are ok and the injection system working correctly as evidenced by everything being ok , any ideas what could be wrong ?

[John_C]

Did your mechanic tell you what the fault codes were when you had the diagnostic done as that's a good place to start?

If you've not got the fault codes then as a starting point you'll need to get them read again so you know what the car thinks is wrong with it.

Cheers,
John

[Bernard333]

No , I should have asked but also I had flattened the battery and the in car display had reset itself so dont know if this affects the fault code memory also ? I will be taking the car back to same mechanic ( local Volvo dealer actually recommended him and hes got a great reputation locally here in Ireland ) , I have lived with the power problem for about 25k miles and every advice I could get pointed to the lift pump which did eventually fail ,have downloaded scantool.net and am planning to buy an obd11 serial connector from ebay so I can see whats wrong for myself but just a bit concerned that I might do something that might bugger up the car completely .

[shimon340]

I didnt think the Bosch system would work successively with a Denso pump fitted. Control system etc would be different leading to interesting(!) pressure control results!

[Bernard333]

the Volvo/Bosch pump that was removed has just two wires to the motor and the Denso pump looked exactly the same even down to the electrical connector in the Volvo mounting assembly fitting into the Denso pump with no mods . The replacing of the pump did immediately resolve the starting problem and I have covered 4000 miles this past 3 weeks ( learning that the fuel tank needs to be 70% full was an expensive one , broke down near St Quentin in France and they charged 164 Euro to bring 25L of Diesel to me , I suppose I was lucky that the breakdown man spoke good english as I could see he was having difficulty believing me that just adding deisel would get it started again especially as he checked himself that the tank was already showing three quarters full - he was shaking his head in disbelief). I cant see that there can be any pressure control for the fuel tank lift pump as its either receiving power or not as its just a 12V pump with a constant 2bar pressure output feeding the low pressure section of the engine mounted pump please correct me if I am wrong , or is there some voltage control applied to the motor to regulate the pressure ?

[shimon340]

ah.. the fuel tank pump.

Interesting that they are so similar. So long as the output at a given voltage is the same then I suppose the denso one could work. The fact the tank needs to be over 70% is interesting. Are there no fault codes registered?

there are a number of reasons why high pressure diesels can cut out, one can be if the high pressure pump pressure regulator fails and the output pressure rises too far, the common rail will note the over pressurisation and release all the pressure from the rail - via a kind of safety valve. This results in the engine cutting out. this should log a fault code however.

alternatively, the low pressure feed pressure is too low. would also trip a fault code though but might explain the 70% issue. below 70% full the output pressure from the pump is too low. high pressure pump maintains rail pressure by measuring input and fuel return levels.

are the symptoms the same now as when the original bosch pump was replaced with the denso one?

alternatively, there is a pressure regulator on the common rail, this could be at fault too. or, if one injector intermittantly returns too much fuel, the HPP responds by cutting the pressure to the rail. This then means the injectors are leaned out which can result in stalling.

where abouts in the uk are you? I have a friend who works for Bosch and who is also a volvo and D5 expert.

[Bernard333]

thanks for the explanation it makes sense , I will go down this route and investigate , unfortunately so far if there has ever been a fault code its always managed to clear itself by the time anyone has been able to plug in to the system . I am based in Donegal Ireland but driving to Glasgow and then Liverpool on a regular basis . Looking at the Denso and Bosch pumps I would say they both came out the same factory down to the same plastic mouldings around the electrical connectors and the metal canister but surely it cant be ! Would be great to get a Bosch engineers angle on it and I am sure you are right that its something to do with pressure that needs the tank to be 70% full so I am not 100% certain now that the Denso pump is ok even though output pressure measurement showed it be 2bar , fuel filter has been changed and fuel pipes have been checked and found to be ok . I now think I have two separate problems , it just seems strange that for normal relaxed style driving you would never know there was anything wrong and the fuel consumption is certainly not affected . Also when I checked with a Volvo main dealer they advised that the fuel pump/sender assembly for D5 models was subject to a number of design changes even over the period 2003 to 2004 ( mine is a Dec 2003 model which they advised I needed the 2004 fuel pump ) , I wonder what problems Volvo may have been having with these to need so many changes .

[shimon340]

hi

try calling my friend Howard on 0161 707 9224. He is a Volvo expert and also works for Bosch.

If you are travelling to Liverpool maybe call in and see him. He's in Manchester so thats just down the M62 from where you are. He has the latest Bosch diagnostic kit too.

He had an S80 recently which keppt cutting out too. I think he changed the low pressure tank pump...

when you speak to him tell him Shimon recommended him via the Volvo club

keep us posted with the updates!

[shimon340]

hi there

how goes things with the D5 V70? did you speak/go to howard??

Shimon

[Laney760]

There is reference on the net to a problem of 'sudden loss of power' in V70s due to the electronic throttle module and it seems that in the USA V70 owner's guide there is actually a reference to this (!) and the recommendation is - to turn off the ignition and restart and the fault clears (as the member posting this said this cleared the fault in his). Bit worrying if you're out on a motorway in the fast overtaking lane! There is also reference to replacing the unit and it quickly having the same problem again. I have to say I read of so many faults in the newer models that I am becoming more inclined to have an engine rebuild in my 940 diesel when it finally dies than buy a newer model Volvo