Volvo V70 II 2.4 B5244S6 Fuel pressure problem

Tomaszabc · Post by **Tomaszabc** » 23 Jan 2020, 11:10

Hi. I have 2004 Volvo V70 2.4 170 HP gasoline. SULEV version B5244S6 USA.
Check Engine is something that i live with. Fuel pressure- that is a problem but engine run fine.
I would like to deal with this issue so i start to check voltages, signals and look for PWM signal. I dont understand, why fuel pump get all the time 5v and no difference. For checking i'm using some kind of oscilloscope.

Wires going to PEM (fuel pressure module) are thick blue, thin blue, yellow and black. Going from module to fuel pump we have Orange and Blue.

From ECM to PEM, at yellow wire there is about 12V all the time.

At thick blue there is kind of oscillating (not PWM in my opinion)signal. From 0 to 3 V.

At Orange wire from PEM to pump there is about 0.8 V and maybe this is negative wire from pump.

At Blue from PEM to pump there is straight 5V.

Att thick blue there is 14V.

Im not expert at electronic issues. Why pump is getting same voltage even if signal at thin blue is oscillating? That is a bit confusing to me. If pump get the same voltage all the time, then it will be no regulation on fuel pressure.

Does anybody have idea what can solve my problem and where the issue is?

Tomaszabc · Post by **Tomaszabc** » 24 Jan 2020, 07:18

Something comes up. I have opened PEM module and there was a lot of oxidation and I'm pretty sure problem is there.
I have read some posts but I'm not sure. PEM number is 0 580 001 001/ 8634953, should I use exact same number or will it cross with different?

Post by **abscate** » 24 Jan 2020, 07:38

You can cross reference part numbers with the Volvo Webstore site which gives part numbers and changes.

Also FCP has afitment guide on each part which I have found to be very reliable.

I found the same corrosion problem on my PEM

Tomaszabc · Post by **Tomaszabc** » 24 Jan 2020, 08:46

I got that information:
Volvo Webstore is little bit easy on this. Everything are correct

so im not sure are they reliable.

Crossing reference is from ford:

That means ford module will be right?

Tomaszabc · Post by **Tomaszabc** » 28 Jan 2020, 10:27

I have changed the PEM for 30769225 and problem is still the same. No difference. Looking on live data on SUN PDL diagnoscope, fuel pressure is from 43.5 psi (3 bar) at engine off to 72.5 (5 bar) at engine running.
My next step is to educate myself and take a good look at fuel pressure sensor or fuel pump. Lastly, issue can be at TCM.

I can't find fuel filter. That's SULEV+ version and fuel system is different.

Any ideas?

Tomaszabc · Post by **Tomaszabc** » 29 Jan 2020, 00:54

Problem solved. Probably fuel module PEM fail and previous owner/mechanic shortened fuel pump ground. Because fuel pump is controlled by negative/ground signal, so it was working on 100% load.
After replacing PEM and remove shorting cable in fuel tank, everything is fine and no check engine light.

https://imgur.com/a/vQdUSfW

Post by **abscate** » 29 Jan 2020, 05:34

That is a nasty piece of work to hack that. Very bad work by the previous owner.

Your troubleshooting path was excellent and efficient.

Post by **vtl** » 29 Jan 2020, 07:48

Nice!

Tomaszabc · Post by **Tomaszabc** » 29 Jan 2020, 08:26

Thanks. I hope that can help somebody. Rare case but this situation can demonstrate how system behave at grounded fuel pump.