I posted earlier about referrals for a Volvo friendly garage in the Lexington area:

http://www.brickboard.com/RWD/volvo/1546295/volvo_friendly_garage_south_lexington_ky.html

In an effort to avoid a tow to a garage I have continued to try to diagnose the problem from afar.

I sent a known good coil assembly and a fuel pressure gauge setup (image below). Replacing the coil did not solve the problem but the pressure results were telling.

The car will sometimes start and run poorly, but not for long. Once the gauge was installed it initially showed just shy of 30psi pressure during cranking and the car started. It ran for several minutes all though it required a feathering of the throttle to keep it running.

During the time the car was running the pressure fluctuated between 15 and almost 30psi. The pressure fluctuations did not correlate to throttle position. The fuel pressure regulator does not have a fuel smell at the vacuum side.

I don't remember what the specs are on Rex Regina fuel pressure but I believe it should be over 40psi. (43?)

So while I think we have found the source of the problem I wonder if it is the pump or perhaps the filter? If the pressure was constantly low I would have a better feeling about pointing a finger at the pump failing. With the varying pressure I wonder if there could be debris moving around inside the filter occasionally allowing a better flow of fuel?

Thanks for any hunches and the pressure specs of the Rex Regina system if you have them.

Randy

Randy,

I agree with Mike, and wouldn't suspect the filter unless it was 3 or 4 times older than the pump. When the brushes get worn way down they don't have the normal contact pressure, which can lead to arcing and burnt spots that cause pressure fluctuations.

The Regina pressure specs ate the same a LH 2.4

36.5 psi at warm idle with vac hose connected
43.5 psi with vac hose pulled and plugged (simulating WOT)



--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I concur with everything Mr. Mullet has said. Classic pump failure. Fortunately they aren't too bad to replace.

---------------
Chris Herbst
Phoenix, AZ

2005 S80 2.5 53k
1992 940 (sold!) 170k
2012 Subaru Forester 2k

I looked back at your original post. The car has 200K on it. If it still has the original pump in it then your friend has been running on borrowed time.

From (failing) memory.... Fuel pressure at idle should be in the neighborhood of 36 psi and hold steady there if the throttle isn't touched. If he jabs the throttle (reduced intake vacuum) the pressure should increase to around 42-44 psi. When it's just sitting there idling there is minimal fuel flow through the filter, so it's doubtful the pressure fluctuations can be blamed on that.

As a final verification that the problem isn't related to a bad relay or some other interuption to the electrical power supply, your friend could dig around by the LH trunk hinge and locate the pink pump power wire. There is a disconnect in that area that provides a handy place to tap into the pink wire with a volt meter and see if there are power flucuations that corrolate with the pressure fluctuations. If the power holds at a steady 12v, then it sounds like it's new pump time - what fun!

Chris,

Thanks for your input.

While it could be more than a fuel system relay fault I did have him swap out that relay as a possibility earlier in the process of chasing this and it did not produce a change.

He is not getting over 30psi and it was dropping to about 15psi during our phone conversation. This was during one of the times that the car was actually running; not well, but running none the less. We haven't talked since that time but I am thinking that perhaps during one of the no start periods the pressure might be much less.

I think he has a new pump in his future.

Randy

hi Randy
we had a rex/regina that was stalling and sometimes not stalling.
i put a gauge on it and it was 2 psi low. a new pump fixed the problem.
if you pinch the return hose the pressure should shoot up instantly but dont hold it pinched very long.
i forget the correct pressures but i think 34-36 comes to mind.
im sure Bruce will have the correct pressure or the FAQ.
im betting the fuel pump and filter needs replacing.
good luck
mike