First I need to check that the pressure is indeed low. What is the best method to check pressure and confirm a bad pump?

Also, do you recommend getting the Hella insert versus the entire assy? I assume the tear-down and replacement is not too difficult.

This car is a wagon. Anything else I need to know?

You really need to remove the cover and pull/inspect the sparkplugs. If they are black or sooty, a vacuum leak will be the primary suspect. Also check the air hose between the filter box and throttle body.

Keep the spare FP relay in the glove box.

Klaus
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Always willing to listen, just not able to take direction.

I did this in May I believe. Cut and past links to pics in the thread below.

http://www.brickboard.com/AWD/volvo/1480703/850/uhoh_start_turbo_wagon.html

I could have used an insert but with a long trip facing me and not knowing how easy it would be to disassemble the unit, I went with an OEM replacement.

Live and learn.

Erwin

Hi, don't forget the fuel pump relay, at this age it migth also be reason for dropping fuel pressure. New costs about $50.
br Tapsa

Thanks. That sounds like a wise suggestion. This car is perfectly maintained and has 150K miles on it.

Where is this relay located on the wagon? I'll change that out first.

Hi, the relay is located below the fuse box cover, often numbered #103.
you migth also test it by hard wiring the relay, pin 15 to 87 key into pos II.
br Tapsa

So you need to remove the screws holding the black plastic fuse box 'surround' then it is underneath it somewhere? I couldn't see it poking around with a flashlight.

Prior to my junk yard trip, it appears that the same part number works for 1994-96 models. How do I tell a '96 from a '97?

Yes, remove the torx bolts and the relay is under there. Its probably red, but could be green with a big 103 on top.

If its stalling out, turn off the radio (so you don't have the antenna making noise when you turn the key) and turn the ignition from off to posII and listen for a little him from the fuel pump. If you can have someone turn the key and you can listen in the trunk would make it easier to hear it.


The fuel pump also has a two stage operation design where one is for idle/low rpm and the other jumps up the amperage for when you're over 2500-3000rpms. If you have a pressure gauge you can verify both ranges getting enough power. Otherwise try replacing and see how it goes.
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If you're not driving it "like its stolen," are you really driving?

Thanks Tapsa.

Since my problem is intermittent, I'll just replace the relay. I've never had the car stall in my driveway or garage where I could troubleshoot the failure.

I'll post again a week or so after I replace the relay.

So I finally installed a new (used) relay and my problem seems to go away for a week, then the car stalled again (twice) while idling with my foot on the brake. The car always has difficulty starting after stalling and, when restarting, seems to only fire on a few cylinders until I give a little more gas. Then the idle smooths out and the car runs fine for another week.

So now I don't believe the relay is the root cause of the problem.

Maybe I have a bad injector. Will the car idle running on 4 cylinders with my foot on the brake (I guess I could pull a wire and find out myself but removing the plastic cover and grounding the lead is not an option anytime soon)?

Any other suggestions?

I hate intermittent problems!

Oh, there are no codes stored in the computer.

Relay position: I have it out and jumpered the contacts to run.

http://img.photobucket.com/albums/0803/eroman/850/HPIM1116.jpg


When I replaced my pump I also replaced the filter. Here's what poured out of the filter.

http://img.photobucket.com/albums/0803/eroman/850/HPIM1113.jpg

By the way, listening for the pump when you turn the key can be misleading. My pump motor would run but apparently, the diaphram or other rubber bits had disintegrated. Maybe that's the black junk collected in filter.

http://img.photobucket.com/albums/0803/eroman/850/HPIM1114.jpg


Erwin

I had a fuel pump go bad on my 850 turbo. It would start, but when I hit the gas, it would conk it. The pump motor had a short in it somewhere. I went through a couple of fuses before I figured that out :o)

I think Bay 13 has a photo instructional of how to get at the fuel pump in an 850 wagon. As I recall, it's under the carpet near the wheelwell by the gas tank. Fuel is always under pressure, so have some sort of container to collect the spewing fuel, and rags to sop up an advertent spray. oh, and put out the stogie too.
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'96 855 Wagon, 200k (and formerly 97 850, 120k)

Good advice, but the fuel is not always under pressure. While the engine is on expect around 40psi. Within one minute of engine shutdown, the psi should fall below 20psi. After about 30 minutes, there should be no pressure.

What will be is fuel in the line, so be careful taking the lines off the fuel pump. An old rag to soak up any spills is always needed, the stench of gasoline in the cabin is not desired.

Klaus
--
Always willing to listen, just not able to take direction.

You can get a fuel pressure gauge at autozone that'll fit. Test off the rail.


Get the entire assembly at a junkyard. They're like $20, and odds are quite good that the system will still be pressurized. If its not, see if there are broken connections in the engine, (ie they unplugged the rail) otherwise I'd grab one from a different car. Just because its not pressurized doesn't mean its bad, but my junkyard usually has 3-4 850s sitting around, so when I needed one I could "shop around"
--
If you're not driving it "like its stolen," are you really driving?