1995 violvo 850 turbo

ariete57 · Post by **ariete57** » 15 Jan 2009, 18:10

Can anyone tell me what the minimum fuel pressure is on a 1995 volvo 850 turbo, and how can I testthe pump and regulator?

Post by **rgrady** » 15 Jan 2009, 18:50

It should hold 43.9 PSI measured at the schrader valve on the end of the injector rail, key on, engine not running.
I just went through this process of low acceleration and no power. It turned out to be the hose inside the fuel pump assembly that connects the pump to the discharge nipple was not connected properly to the discharge nipple so I was not getting the required pressure.
If you check the pressure and it jumps up to proper pressure then falls to a low pressure within in few seconds then check the hose in the fuel pump assembly first.

Post by **Ozark Lee** » 15 Jan 2009, 18:55

rgrady beat me to it but here are a few other nuggets:

Normal fuel pressure is in the 44 PSI range. If the FPR is working correctly you should be able to clamp off the fuel return line and it will climb rapidly (Don't let it get over 55 PSI or so). Once the fuel return line is unclamped it should settle back to the normal range.

The other test is to turn the car off and see if fuel pressure is maintained. If it rapidly falls off it may be a bad check valve in the fuel pump (hard starting) or a breach in the FPR diaphragm. The latter will cause the car to flood.

...Lee