I sure thought the fuel pump relay would be it

belyle · Post by **belyle** » 14 Dec 2012, 18:50

Last Tuesday on my way home, my '96 850 Turbo up and died on me. No warning, no lights, no real sputtering, just dead. I couldn't start it but it cranked over fine. After sitting a few seconds, it sort of tried to start but sounded like only one cylinder was working. I couldn't even limp to the side of the road. I had had no other issues with the car until it just died.

After reading through a bunch of topics here, I thought I'd start by reading the codes and by testing the fuel pump relay. The fuel pump relay is the original one (210k+ miles), so it seemed like a good place to start. OBD revealed two codes: Fuel Rich and O2 sensor slow response. I figured those two codes were because I tried to start my car so much after it died, including pumping the gas. No engine light on, but it does work when in position II.

I jumped the relay slot and my fuel pump kicked on immediately. Problem solved! I bought a new relay today and installed it. Everything seemed OK. I ran some errands and no problems.

I came back out to my car after about an hour and it started fine, but hesitated a little when accelerating. It tended to idle a little rough. It is stuttering when taking off from a stop, but once rolling along it's OK.

I'm wondering what else I should check next. I am thinking something may have screwed up when (if?) the fuel pump relay died and/or I kept trying to start it. I really don't want to have to get another tow home, so I want to make 100%sure the car is fixed before driving it to work again.

Post by **cn90** » 14 Dec 2012, 18:58

Maybe your fuel pump is on the way out.
Search forum for Walbro vs Bosch.

At 210K, I'd replace the fuel pump and fuel filter anyway.

Post by **jblackburn** » 14 Dec 2012, 21:17

I would check fuel pressure at the rail. You should see 38 at idle and around 43 under moderate throttle.

See if there are any more stored codes. If those two are back, it may indicate a mass airflow sensor problem or dirty sensor.

Post by **erikv11** » 14 Dec 2012, 21:33

Or a vacuum leak?

belyle · Post by **belyle** » 15 Dec 2012, 08:25

jblackburn wrote:I would check fuel pressure at the rail. You should see 38 at idle and around 43 under moderate throttle.

See if there are any more stored codes. If those two are back, it may indicate a mass airflow sensor problem or dirty sensor.

How do I check the fuel pressure at the rail? I have to clear the codes and check then again. I forgot to clear them the other night.

Post by **jblackburn** » 15 Dec 2012, 10:25

There's a blue cap under the black plastic cover over the throttle body. Undeneath that is a normal tire valve that you can connect a fuel pressure gauge to. You can probably pick up a cheap one somewhere at an auto parts store (or Harbor Freight if there's one close to you - great store).

Vacuum leak idea could also turn up something.

belyle · Post by **belyle** » 16 Dec 2012, 11:00

I went out this morning to try a couple things. First off, I checked my fuel pressure . I used a tire gauge, but pressure is pressure. It read 38 psi at idle. Seems about right.

While I have the little cover off, I noticed a hissing sound. Turns out, there was an open vacuum port. A couple months ago, I found a hose that was not connected to anything in that vicinity, but couldn't find any place to plug it so I ignored it. I plugged the hose on to the open port and no more hissing.

I checked my oil and it's really low. I have never noticed it leaking oil, but I am not sure I've ever checked it between oil changes (my bad).

I took it out for a test drive to the local auto parts store. Everything seemed OK until it got good and warmed up. Then, it started missing at idle and stuttering a little at take-off. Once moving along, everything was great. Plenty of power, seemed normal.

I noticed though that in Drive or Reverse, it stutters/misfires at idle. In Neutral or Park no stutter or misfire.

I think it's really really weird that it never did this before the car died out earlier this week.

At this point, I'll definitely be taking my other car to work. Not trusting the 850 until I'm 100% sure I've solved the root cause.

Post by **erikv11** » 16 Dec 2012, 13:43

I would try cleaning the Idle Air Control valve (IAC valve). Just as routine maintenance and to rule it out as a problem.

You just need carb cleaner and a few minutes, maybe a few hose clamps if your still has the original clamp style (in which case it is probably dirty, too!). Remove the IAC, spray carb cleaner inside, shake it around (protect your eyes!), dump out the carb cleaner on a rag. Repeat until the valve inside moves freely upon shaking and no more gunk comes out with the carb cleaner.

ThommyKent · Post by **ThommyKent** » 16 Dec 2012, 15:45

Mine did the same thing. You need new Plug Wires.Get Volvo OEM Bouicord brand. .Old wires will cause misfires under slight loads like going from park to drive. Fixed mine. I would throw in plugs (again Volvo brand) and cap and rotor. If your wires are the original ones, they will be date code stamped and you can identify how old they are.

belyle · Post by **belyle** » 17 Dec 2012, 07:32

What would the advantage of using "Volvo" branded plug wires and plugs be? Seems like plugs are plugs and wires are wires. I know they don't like the platinum plugs, but other than that, can anyone else chime in on using Autolite or Bosch or whatever else?