1993 Volvo 850 with 256 kmi Stalled and will not start.

The car was driven a couple of miles. It was behaving well but had a fairly rough idle. The car came to a stop, the accelerator was press, the car began to move and then stalled and has not started since.

The plugs are new and have good spark The fuel rail has 43 psi. Pressure bleeds away overnight. The pressure reaches 43 psi very quickly.

If i crank the engine, the plugs do not appear to be wet. If I stick in a twist of paper towel in the spark plug hole in place of a plug, the towel does not appear to be wet after a 5 second crank. I can however smell gas then.

-The resistance of the VSS speed sensor is 1740 ohms instead of the expected 200 ohms.

-There is 11 volts between CMP sensor term 3 and ground (10 V is expected)

-CMP terminal 1 to ground is 0 ohms, as desired

-when I check the power stage control signal (terminal 4 to ground) I get 0.2 volts, where I read I should have 0.7-1.3 V (what does this mean?)

I have an 98 S70 to pull parts from.

Questions:

  1. I have a diagnosis write up(named "BasicTesting-Turbo.pdf" for a Volvo and it says to use a breakout box( I don't have one) for a CMP sensor test, that is "check between BOBox terminal 20 and 4 and Operate the starter voltage should vary between 0-5 volts" Would the terminals 20 and 4 correspond to wires labeled 20 and 4 in a Haynes Volvo 850 wiring diagram?

  1. Can a ECU from a 98 s70 go in an 850? Roughly what would I have to pay for an ECU?

  2. What do I do next? I wish I had a better write-up.

Thanks for reading. Many Thanks, Mark

Reply to
Mark Barron
Loading thread data ...

Do you know if you're getting a spark? That's the first thing I'd check, if you have a spark, then the problem is probably fuel, but if you smell gas, I'm leaning towards ignition.

Reply to
James Sweet

I removed the air filter assembly and shot Starter Fluid into the intake. It did not fire although the engine turned over well. I quess I will swap CMP sensor from my 98 s70. Thanks, Mark

Reply to
Mark Barron

I have spark, but even when I squirt starter fluid into the intake directly, I can not get the engine to even cough. How can that be? I will check again to insure that I still have spark. Thanks you for replying. Mark

Reply to
Mark Barron

Is there compression? Timing belt didn't break did it?

Reply to
James Sweet

Belts are good, I replace the timing belt last summer, I honestly have not checked compression will do tonight. I think I may have found the problem. I tested voltage at 3 of the five injector connectors. The wires are green and white. When I turn on the ignition, BOTH wires have battery voltage , +12.85. Is this right? Does one of the wires get cyclically grounded by the ECU and thereby cause the injector to fire? Or is this situation indicative of wires crossed? I am not yet sure where the green and white injector wires run, I am guessing to the ECU. Let's say for argument, that the cause of the no start is the fact that the injectors don't fire. If I find 12.8 at the injectors then what is left to explain the injectors not firing? -- The ECU right? Thanks for reading.

Reply to
Mark Barron

Generally speaking, yes, one wire receives +12V and the other is pulled low by a power transistor in the ECU. The pulse is brief though, especially at start/idle. You really need to connect a test light across the injector connector and crank it, if all is well the light will flash. Sometimes you can also hear the injectors tick but the starter can drown it out.

Reply to
James Sweet

The timing belt did not break. I got the following compression readings

1-4. Battery was too low to get #5. 75 85 98 65 psi
Reply to
Mark Barron

I will be on the hunt for what I think is called a noid light. Thanks!

Reply to
Mark Barron

That's the tool designed for the job, but it's not the only way to do it. In a pinch you can take one of those wedge based bulbs used as side markers on a lot of cars, bend down the wire contacts and poke them into the injector connector. Another approach is a regular automotive test light, the sort that looks similar to a screwdriver with a sharp tip and a bulb in the handle. Poke some thin wires into the contact sockets on the injector connector and connect the test light there.

Reply to
James Sweet

the IAC does buzz. I have ordered a Fuel Injector Main Relay, circa $29, since I don't see anything wrong with the wiring. I am so grateful for your input. I will advise.

Reply to
Mark Barron

Did you check the output of the injectors? I'm not sure where the relay is wired in those cars, but normally that just serves to control power to the whole system, a relay is much too slow to do the actual injector pulsing. Don't just throw money at it, diagnose.

Reply to
James Sweet

Check the distributor cap to make sure there are no cracks. I put a brand new one on (aftermarket) that had a crack. Caused rough idle and dying at stoplights like it had bad gas. Drove me to drink b4 an excellent mechanic in Austin, Tx (hey Troll!) finally figured it out ;-) Good luck! jimmy

Reply to
jimmy

My 850 would do this occasionally, and the only way I found to get it going was to turn the key and crank the engine until it did start. this could take quite a long time, and I am talking several minutes not seconds. I always thought the battery would give out but it never did, you just got to keep your nerve Chris.

Reply to
bassdiva

That sounds like the relay coil resistance, I don't know the pinout off hand, but if that's what it is, then that's about right.

With the ignition turned on there is voltage there, so if you try checking resistance you'll get a meaningless value. In this case it sounds like your meter is effectively pegged.

Reply to
James Sweet

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.