98 S70 T5 - no fuel pressure

shegarty · Post by **shegarty** » 21 Jan 2018, 12:41

Hi folks - so I have been chasing a no start problem now for a long time on my 98 S70 T5. There are some details here and here but the long and short of it is that it started out being a hard/no start issue only in cold weather (below -15ºC) and has now migrated to being a hard/no start all the time. Once it is running there have been no issues except an odd stumble that appears infrequently and that I believe was tied to a bad vacuum line to the fuel pressure regulator which has now been rectified.

I have replaced the cam and crank sensors, ECT and still no progression. I recently thought I had narrowed it down to a lack of fuel pressure after sitting for 20+ hours. When checking after this length of time there would be no pressure at the rail (meaning that depressing the shcrader valve resulted in no fuel coming out - once the system is pressurized fuel will spit out as expected) but if I cycled the key to Position 2 3-4 times to prime the system it would start. Also, after sitting for 5-10 hours with the engine cold it would also start. Doing some research on the forum led me to believe that the check valve which is integral to the fuel pump housing was bad so I replaced the pump assembly with a whole new Volvo unit yesterday.

When I went out this afternoon to try starting it again there was no pressure at the rail and it failed to start by just turning it over normally. I also tried the new fuel pump relay that I ordered at the same time as the pump and no dice. When I cycled the key a few times before trying again I was able to get it running but it was quite rough for the first 10-15 seconds. I have checked the entire system for leaks and that there are none. So, now I am at a loss ... what should I do next? Install my own check valve on the line leading to the fuel filter? Any help would be greatly appreciated.

addendum - just reading through a few other posts - I have had the P0455 evap code for a long time now, could this possibly be a culprit in allowing a route for air to infiltrate and allow the system to loose pressure over time???

Post by **tryingbe** » 21 Jan 2018, 12:50

Was the fuel filter changed?

shegarty · Post by **shegarty** » 21 Jan 2018, 12:56

yeah, its fairly new - if it was clogged or having issues I would imagine that it would also lead to drive-ability issues. I doubt that a clogged filter would lead to a loss in pressure.

Post by **RickHaleParker** » 21 Jan 2018, 12:58

It looks to me like there is one pathway you have not covered. Fuel pressure bleeding off through a leaking fuel injector.

shegarty · Post by **shegarty** » 21 Jan 2018, 13:03

That sounds possible Rick - how exactly would I check that?

Post by **RickHaleParker** » 21 Jan 2018, 13:15

Pull the fuel rail with injectors and fuel line attached.
Reconnect wiring harness.
Turn key a couple of time to pressurize fuel rail but do not crank.
Look for leaks.

Paper towel under the injectors will help spot fuel leaks faster and better.

Post by **scot850** » 21 Jan 2018, 13:23

Smell the engine oil shortly after switching off from the dipstick and see if it has a smell of gasoline.

Neil.

shegarty · Post by **shegarty** » 21 Jan 2018, 13:55

RickHaleParker wrote: ↑21 Jan 2018, 13:15
Pull the fuel rail with injectors and fuel line attached.
Reconnect wiring harness.
Turn key a couple of time to pressurize fuel rail but do not crank.
Look for leaks.
Paper towel under the injectors will help spot fuel leaks faster and better.

Will try this tomorrow and let you know how I make out - hopefully I will be able to coax the injectors out the manifold without them coming out of the intake first. If not I am pretty sure I have new o-rings, I have found in the past that they are not reusable!

shegarty · Post by **shegarty** » 21 Jan 2018, 14:37

Should I find a leaky injector does anyone have a set of whites for sale???

Post by **abscate** » 21 Jan 2018, 15:21

Get a fuel gauge on that valve and get some real measurements

It’s normal for pressure to be gone overnight, the spec is something like 50 psi and 30 psi after 20 minutes. You cannot predict pressure by how much it squirts, get some good data