Hello all.
Car is a 1994 Volvo 850, non-Turbo, with about 220,000 miles on it. I've had it for just over a year, and it always started right up.

One day it died right after I'd started it. I could not get it to start again. It would Crank, but not start. I made sure nothing obvious was wrong. Fuel, temp, etc. Checked for loose wires. Nothing. So I had it towed to a volvo shop nearby. It was after hours so I took the bus home.

Next day the mechanic called and said it starts right up for him! He couldn't find anything wrong with it. They replaced the distrib cap and rotor and wires and plugs (related more to my other complaint of it hesitating).

When I went to pick it up, it cranked but wouldn't start. The mechanic couldn't believe it. He sat in it, and IT STARTED RIGHT UP for him.

He was baffled. We stopped and started it about 10 times, and it never repeated the behavior.

Anyway I paid and went home. 2 Weeks later, after it'd been fine, it died while I was driving at a steady speed. I pulled over and tried to restart... it would crank, but not start. Frustrated, I sat there for a few minutes. Then before calling for a tow, tried again and it started !

I don't trust the car, so my question is: ANY IDEAS?

Here is the real catch: The computer will not communicate. The mechanic said the OBDC doesn't send anything at all. And the self-diagnostic LED built into the computer also does not function. This probably is caused by a jolt it got in a collision before I got the car.

Mechanic said he DOESN'T think it's the cam or crank position sensors, because once they fail, they tend to stay failed. Same story with the fuel pump.

SO... with no way to read the codes, does anybody have any suggestions? Should I replace the computer? Give up? Have another beer?

Thanks folks,

- james

Replace the Ignition Control Module and coil:

While we find your parts, please enter your ZIP Code at PartsAmerica.com

TX,
I really appreciate the response. Once you said it and I thought about it, I agreed that the control module & coil was a good bet, so I replaced the part. I confirmed that before I put it in, the car was not starting. However, it still does not start with the new part. I checked for spark at 2 different plug wires by pulling the wires from the plugs, inserting a screwdriver, and turning the ignition. There was no spark.

I'm going to follow some more troubleshooting procedures today, but was hoping you could offer any other bits of advice or ideas. A bad crank position sensor wouldn't case ZERO spark, would it? I thought it'd just cause spark at the wrong times. Am I looking at a possible bad ECM?

Thanks again,

James

It sounds like the ECM may be bad. Using a multimeter, check for reference voltages at select sensors; e.g. MAP sensor or Throttle Position Sensor. If there are none, or woefully low, the ECM is likely bad. Read Sticky, Section A. Many Civic ECMs, for instance, only last around 120,000 miles or 10 years; however, I'm not familiar with Volvo ECMs. Be sure to check all under-dash and under-hood fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-t...tml#post252145

It could be a bad ECM; however, if the crank sensor isn't reading, then that will cause a no-spark condition. Have you checked to see if there is fuel when it won't start?

Hello:

I'm NOT a mechanic... But, I'll relay what my older Volvo did all the time. After it heated up pretty good on the highway, it would vapor lock, and die. When it cooled down a bit, it would start right up.

I had a fuel injection system, and I had an electronic fuel pump. When it was locked, the overheated fuel pump would be humming loudly...

Or, I'm out to lunch.

excon

Thanks for the info. This afternoon when I get home I'll use a multimeter to troubleshoot the sensors.

Will post any results I find. Cheers, james

Hello.
Now the car does not start at all. The intermittent problem has become constant.

Following my shop manual, I tested the Camshaft Position sensor, and it is within specified range. Next I tested the Crankshaft position sensor connector, which has 3 leads. #1 is supposed to be ground, #2 supposed to be 5V, and #3 is supposed to be battery voltage (~12V) with ignition ON.

In my test, I found 12V (12.3V) at all 3 input/output leads.

The shop manual says the following: "If the input or output leads are not within range, repair the circuit."

Repair the Circuit? Can somebody tell me what that might mean?

When I look at the wiring diagram, the 3 leads from the sensor are drawn directly to 3 terminals of the ECM. The way I read it, it's suggesting the ECM has gone bad. The ECM is not sending the proper voltages to the sensor, and thus even if the sensor is still good (which is likely), it will not send proper responses.

I've verified that the fuse to the ECM is good, and the ECM is supplied with 12V. Beyond that, what am I missing?

A more important question is, how can I find a good ECM? My favorite parts suppliers online (RockAuto, FCPGroton) do not stock controle modules. Am I stuck with Ebay? A Volvo dealer?

Really appreciate the assistance, as always. Cheers.