P0305 Fuel Regulator/Pump?

dinosd · Post by **dinosd** » 21 Dec 2019, 19:35

2002 Volvo V70 (non-turbo) 212,000 miles

I’ve been trying to help my son trouble shoot a P0305 - miss-fire on cylinder 5. It has been running rough upon start-up, but then settles in and seems to run normal. The code doesn’t show up on every start, but maybe every 2 or 3 days.

Weekend one: Coils
We replaced the plugs and coils within the last 6 months, so they are relatively new (Volvo plugs, Bosch coils), but first switch the #5 and #4 coils just to rule that out. (No change.)

Weekend two: Plugs
Next we removed and inspected the # 5 spark plug. It looked normal. But we went ahead and switched the #4 & #5 just to see if the code followed. It did not (no change)

Weekend three: Compression
We pulled the fuse on the fuel pump and did a compression test.
# 1 185
#2 180
#3 165
#4 180
#5 180

All of the plugs looked normal.

Weekend four: Injectors
We removed the fuel rail, inspected and cleaned the injectors with throttle body cleaner. This car has the Denso injectors, all of which have hairline cracks in the casing near the nozzle end. I’m not sure if this is a potential issue or not? We replaced the rubber gaskets and then swapped the #4 and #5 injectors to see if the code would follow. It did not. (no Change)

Weekend six: Fuel Pressure.
Following the instructions on the test kit, by turning the ignition to the “run” position for three seconds in 10 second intervals, the fuel pressure went up 10 psi each time until it reached a maximum of 48 psi. Then we let it sit and observed 30 minutes later that it dropped to 32 psi (16 psi loss) 30 minutes after that it had dropped to 27 psi. We measured 27 psi with the car idling. Are these specs normal for this car? Suspecting maybe we have a regulator or fuel pump issue, I had him turn the key to the on-position a few times to “prime” it before he actually started the car. (Each time he drove.) No code all week… until Friday, he could remember if he primed it (he said he got lazy) However, this time he got a P0300 – Random/multiple cylinder misfire. I was still thinking regulator, but later in the day he got a low coolant warning. (He has apparently been topping it up every few weeks)

Weekend seven: Hydrocarbon test.
So the coolant loss pointed me back to a possible cylinder breach. However, the hydrocarbon test did not change color at all indicating no hydrocarbons present in the coolant. I did observe the telltale white deposits/dripping from one of the heater hose connections. The screw on the clamp was not very tight. Hopefully this WAS the source of the coolant loss and is unrelated to the misfire issue.

Any advise where to look next? Can the fuel regulator be replaced independent of the pump?

Post by **RickHaleParker** » 21 Dec 2019, 23:01

dinosd wrote: ↑21 Dec 2019, 19:35 Any advise where to look next?

1. Battery condition.
2. Connector Oxidation, Fuel injectors, Coils, ECM and wiring defects in between.

Post by **abscate** » 22 Dec 2019, 00:42

We measured 27 psi with the car idling

I believe P2 spec is 52 psi , so it looks like you should focus on fuel delivery,

These cars use the CEM andPEM modules to regulate fuel flow rather than the “ traditional “ fuel pump relay.

I experienced a PEM failure on my 2005 and wrote it up here

dinosd · Post by **dinosd** » 22 Dec 2019, 10:45

Thanks. I read your write up and other posts on the PEM issue. I definitely don't have the electronics background to test and diagnose the PEM, but will try to locate it and inspect it for corrosion ... next weekend, kid took it to the desert to go hiking today! Several posts suggested swapping it out with $15 one from a salvage yard, but if it's a common problem, how do I know that one isn't bad as well? Does anyone sell tested "reconditioned" modules? Also, I noticed on Volvo parts websites, there are different part PEM numbers for cars with plastic gas tanks vs.cars with metal gas tanks listed for the same years and models. (I haven't checked which one ours has yet) but is there a general rule which year they switched or is it a S60/V70 vs models?

Post by **abscate** » 22 Dec 2019, 11:46

Get one from a wrecked car in the junkyard, you van pretty much count on that it worked.

I think you will have fewer problems in dry SAN than we do up here.

The price for certainty is steep, about $350 new , but that’s what I did , since this car is often 500 miles from home, so she gets new Volvo part only.

I,think pretty much any PEM from 2001-2008 will work, but it isn’t hard to confirm part numbers either

Supergrunged · Post by **Supergrunged** » 22 Dec 2019, 15:09

Depending on the chassis number, 2002 didn't have a PEM, but still a fuel pump relay located on the stack for the CEM under the dash drivers side.

I know this, because I have a 2003, that is supposed to have a PEM, but is 50,000 units from when the PEM model number changed.
I would plan on replacing the fuel pump as needed, but I suspect it's the Fuel Pump Relay under the dash. Also could be the regulator under the fuel rail, as that year, I don't believe the sensor was at the end of the rail. If it was, I'd replace it still. The pressure sensor, and fuel pump relay are cheap enough parts

Post by **oragex** » 22 Dec 2019, 16:52

Other leads - look along coils wires, sometimes gets crushed by the small engine cover. Check ground wire bend the engine. Check wires to the coolant temp sensor electrical connector. May also replace the fuel filter on plastic gas tanks.

Post by **RickHaleParker** » 22 Dec 2019, 20:10

abscate wrote: ↑22 Dec 2019, 00:42 I believe P2 spec is 52 psi , so it looks like you should focus on fuel delivery,

Fuel line pressure Desired value
Relative pressure 380 kPa ( 55 PSI )
Absolute pressure 480 kPa ( 70 PSI )

dinosd · Post by **dinosd** » 23 Dec 2019, 08:52

Supergrunged wrote: ↑22 Dec 2019, 15:09 Depending on the chassis number, 2002 didn't have a PEM, but still a fuel pump relay located on the stack for the CEM under the dash drivers side.

I know this, because I have a 2003, that is supposed to have a PEM, but is 50,000 units from when the PEM model number changed.
I would plan on replacing the fuel pump as needed, but I suspect it's the Fuel Pump Relay under the dash. Also could be the regulator under the fuel rail, as that year, I don't believe the sensor was at the end of the rail. If it was, I'd replace it still. The pressure sensor, and fuel pump relay are cheap enough parts

Thanks! I need to do some investigating to see if this car has a PEM or a relay under the dash. You are correct this car does not have the sensor at the end of the rail and it does have the It there a way too test the regulator under the rail Volvo calls it a "damper" It appears to be a discontinued part, is there a way to test it?

dinosd · Post by **dinosd** » 23 Dec 2019, 08:53

Thanks everyone! Lot of good leads to check.