Sudden Fuel Pressure Loss '05 v70 n/a

Faust · Post by **Faust** » 31 Oct 2024, 06:35

When I attempt to start my Volvo, fuel pressure kicks up to about 40psi. When the pump stops it's 5 second run, pressure rapidly fall to about zero. Won't start of course.

Post by **abscate** » 31 Oct 2024, 07:09

That’s way under pressure but troubleshoot PEM, wiring, system before going after pump replacememt

Faust · Post by **Faust** » 31 Oct 2024, 08:48

The corrugated hose on the pump had developed a pin hole leak. and caused the original problem. I am confident that I patched that. Wrapped it with rubber and put on a fuel injection clamp. High pressure leak no longer visible.

Faust · Post by **Faust** » 31 Oct 2024, 12:37

" That’s way under pressure" Working by myself with hard time to keep meter visible. I may be wrong on the highest pressure, but not the rapid drop to zero.

Post by **abscate** » 02 Nov 2024, 06:03

For a P2 the spec is 54-57 psi on key turn. And >29 psi after 20 minutes key off.

This assumes B+ is good

Faust · Post by **Faust** » 02 Nov 2024, 17:23

It could be reaching mid 50's, hard to get pressure gauge in easy position to watch (short hose). When the pump stops after five seconds, you can watch the gauge drop to zero, maybe 10 seconds

Faust · Post by **Faust** » 04 Nov 2024, 09:12

OK, after diagnostics, I am assuming that the fuel pump check valve is at fault. Can anyone tell me where this is on a '05 V70. I am fearing that it is part of the fuel pump, is that correct?

Post by **erikv11** » 04 Nov 2024, 11:56

I'm confused by the sequence of events?

1. fuel pressure drops rapidly to zero
2. fixed a pinhole leak, problem gone

those two make sense, but how do you get from there to
3. it must be the check valve

Are you saying the problem never got fixed? It seemed fixed but suddenly came back? If it seemed fixed but came back, did you eliminate PEM as cause (sounds like it, just checking)?

The check valve is inside the fuel pump. If you don't want to mess with inline check valves, the only solution would be to replace the pump.

Faust · Post by **Faust** » 04 Nov 2024, 13:17

Whole story. Can appeared to run out of gas. I had recently replaced the fuel pump with one from my parts car, and had left seat out for easy inspection if things did not go well. Opening it up I found high pressure leak on the corrugated hose on the pump. As luck would have it, I found myself broken down in front of a house where the guy's hobby is antique cars. Together we were able to cut come rubber to wrap the pipe and secure it with a fuel injection clamp. It appeared that the leak had been solved by watching through the floor hatch. Still, car would not start. I had AAA tow it to my house. I then tested fuel pressure and found that it would pump up to around 50lbs, then fall to zero immediately when the pump finished it's five seconds. Then, because it is always recommended, I replaced the pressure sensor with a known good one. No difference. So that is where I am, no visible leak from the pump and a rapid fall off in pressure, so I am thinking check valve. I am not anxious to replace the pump again because the last time the job took almost two weeks before I found the right combination of led lights and mirrors.