1994 850 Turbo Randomly Shutting Off

IG-88A · Post by **IG-88A** » 29 Jan 2015, 12:29

Like the title says, the car will just randomly shut down, as if I've turned the key back a notch. This had happened three times shortly after buying the car back in May, and just happened again two nights ago. When it happens, the car won't instantly start right back up. But if you try for a minute or two, it'll fire right up and run just fine. I've ordered a cam position sensor from FCP, and I plan on taking that step once its delivered. But I was under the impression that a faulty cam sensor would throw a code. I do have an EVAP code 315 that I can't seem to track down, and a randomly recurring 143 knock sensor code that I'm planning on replacing both sensors to try to rectify. This random shutdown doesn't seem to correlate with either of these two codes at all. In fact, after the incident the other night, I instantly checked my codes via the diagnostic box, and no codes were present at all . But the KS code and EVAP code came back today. My A-6 diagnostic port doesn't seem to work. And its my understanding that on 94s, the ignition diagnostics are handled via the OBD2 port under the coin holder. Correct me if I'm wrong. I used an OBD2 scanner from Autozone today, and it was unable to find anything. Since owning the car, I have replaced the PCV system and cleaned all involved parts along with the IAC and throttle body. I have replaced the coolant temp sensor and thermostat. And just last week I replaced the plugs (Volvo), wires (Bougicord), cap, rotor, air filter, fuel filter. Any help as to how/why this problem is ocurring with no corresponding code would be appreciated. As well as any other things to check on when trying to diagnose the 143 KS code. I'm hoping the sensor replacement will help that. And I'll add that I only use 91 fuel. Sorry for throwing possibly too many other issues into the mix and/or too much info. But it always helps to throw it all out there in hopes some of it may help lead to a solution. Thank again.

Post by **abscate** » 29 Jan 2015, 12:59

Ignition switch (electrical part) and fuel pump relay are two common causes of this symptom.

Try searching to learn about these, Ill find links and post shortly.

IG-88A · Post by **IG-88A** » 29 Jan 2015, 13:35

Thanks. I've read about the fuel pump relay being an issue, but didn't consider the ignition. The relay didn't even dawn on me for some reason. I may as well order both of these as well.

Post by **cn90** » 29 Jan 2015, 13:50

"Random-turning-off" potential culprits in an 850...

- B cable
- ignition switch in cars with high mileage
- MAF (usually there is an error code)
- ECT (but usually cold start issue)
- fuel pump relay, search for Ozark Lee DIY using Radio Shack capacitors vs jumper wire btw 15 and 87.
- fuel pump itself, if so google for Bosch 69693 and posts by "stephansvolvo".

Post by **erikv11** » 29 Jan 2015, 14:13

Common for a cam sensor that fails intermittently to not throw a code.

IG-88A · Post by **IG-88A** » 29 Jan 2015, 14:18

thanks much. ECT was replaced only a couple of months ago along with the T-stat. I've had no MAF codes, and cleaned MAF with CRC cleaner recently. A new ignition switch and fuel pump relay are on the way. So all that I'll have left to possibly address will be the battery cables and the fuel pump motor, if these other items fail to cure it. The thing is, it could take another seven months to realize that the problem is still there, waiting. Thank you all for the guidance.

IG-88A · Post by **IG-88A** » 31 Jan 2015, 08:45

A bit of an update. While driving home yesterday, I pulled into an auto parts store to buy some cleaning products. Upon returning to the car, it wouldn't fire up. I thought, "Haha. I've got you now!" and promptly went in to borrow their fuel pressure gauge, in hopes I could either detect low pressure, or rule out a fuel pressure problem. Much to my chagrin, The fitting on their gauge was too big to fit between the schrader valve and the bracket for the throttle cable. At any rate, it finally started and I made it home. When I arrived, I thought I'd just swap the fuel pump relay from the '95 into the '94 and see if i noticed a difference, since the '95 hasn't exhibited this problem. I fully expected to see old yellow relays in both vehicles. Or at the very least, in the '94. The '95 had the old yellow relay, but the '94 had the new red one with the current part number. Even stranger is that the red relay also had a dab of burgundy colored paint on top, making me think that it was original to the car. Very strange. Anyway, I installed the yellow relay for now to see if I notice any changes, until my new parts arrive. Am I correct in assuming that all the parts I see under the hood that have little paint stripes on them are factory installed parts? If so, it's odd to me that they would use that red relay way back in '94, only to switch to the yellow ones, and then back to the reds.

Post by **erikv11** » 31 Jan 2015, 09:24

I have about 10 fuel pump relays from Volvo, every one of them has a 6 digit code on the side, that is a date code. If it dates to 94 etc., then it is original.

nascenta · Post by **nascenta** » 31 Jan 2015, 14:55

When you try to restart is everything lighting up and the starter spinning? Or is it black; no lights in the dash?

IG-88A · Post by **IG-88A** » 02 Feb 2015, 07:41

nascenta wrote:When you try to restart is everything lighting up and the starter spinning? Or is it black; no lights in the dash?

All is normal when I try to restart it. Dash lights on, starter cranking. I will add that I've never had a cold start problem ever.

So far, I haven't had any issues since the fuel pump relay swap. But then again, its only been a couple of days. This issue went away for several months before, to the point of me actually forgetting about it. Time will tell on this one, I suppose. Thanks to all for your assistance. I'll report back with any changes and/or findings.