1994 Volvo 850 GL randomly stopping

Question

My 1994 Volvo 850 GL has recently begun to halt the engine at seemingly random intervals. Some backstory: Since I bought it second-hand in 2013, it's had an intermittent problem where when I start the car back up a short time after having used it, it'll immediately die, and refuses to start back up unless I let it sit in neutral with the power turned off for 1-2 minutes. This occurred pretty rarely, maybe once a month or so, and was never an inconvenience since the car would start back up and run perfectly again after waiting a few minutes.

However, the last couple of weeks, this has started happening while the car is running and in motion. While driving a friend home last weekend, the car suddenly stopped responding to the accelerator, all the dashboard lights lit up, and the car rolled to a stop. I first attempted to start it back up immediately, being a little panicked to be stopped in what was essentially the middle of the road. It didn't work, so I flipped on my emergency blinkers, waited two minutes, and it started back up without so much as a cough from the engine.

Yesterday, the exact same thing happened on my way home from work. I was doing 80kph, and suddenly the accelerator stops responding, all dashboard lights light up, and the car is unresponsive until I let it sit for a few minutes.

My first suspect during these stops has been the battery, but all electronic systems such as the AC and the stereo keeps working, and there are no other signs of excessive battery use that would "out-drain" the charge provided by the alternators.

My father, although not a car mechanic, has experience with Volvo 850 maintenance and repairs, and has told me it might be the petrol filter, or the lid that keeps the spark plug cables in place on the engine block. However, he's unable to help me start tinkering with the car until at least the end of this weekend, so even though I know the basics of what components are and what they do, I don't feel confident enough to start messing with the car on my own. I got a severe backlash on my taxes this year, and have very little money left over, let alone for a mechanic or a garage. This is my only car, and I need it to run for at least another half year to a year, when I've saved up enough to replace it.

What could be causing this problem?

Answer 1

I had an '94 940 GL with the same problem. While it could be any number of things, my issue was a failing ignition coil. Initially the car would stall and be able to quickly be restarted. But since the problem 'fixed itself' I could not figure out what it was. Eventually it got bad enough that I slept overnight in a church parking lot far from home before it would restart in the morning. I fixed it just in time to sell it.

In any failure to start scenario troubleshooting, one isolates broadly what the engine is not receiving to run - gas, spark, air. In this case I'm suggesting a failure to spark. The ignition coil provides high voltage to the spark plug cables and to the spark plugs.

When your issue occurs, what you could do is remove a spark plug wire, connect it to a spare spark plug, ground the spark plug to the block or other grounded metal, and crank the car to check for visible spark. Be careful as this is high voltage, and the idea is to ground the plug's threads similar to how they normally are when installed (the threads ground to the block).

To isolate fuel as the source of the problem, you could use a can of starter spray, and when the problem occurs, spray some into the air intake and attempt to start the car. If it will run for a few seconds with spray but not on it's own, their is a fuel delivery problem. Cheap checks are the fuel pump relay. More difficult checks are a fuel rail pressure test.

Answer 2

could be sludge in the gas tank coming to cover the gas filter intake therefore cutting of the gas supply, and causing the car to stall, some folks say it starts after a few minutes no problem this is because the junk in the gas tank for lack of a better word has moved off the gas filter intake, you might try draining the gas tank and putting in fresh fuel.. just a thought.