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?

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

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

Thanks for reading.
Many Thanks, Mark

 

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.

 

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

 

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

 

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

 

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.

 

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.

 

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

 

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

 

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.

 

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.

 

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.

 

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

 

When you say, 'check output of injectors' you must mean pulling
injectors to see gasoline
spray right?

I have replaced the distributor cap. I thought the distributor rotor
looked ok.

I tried again to start the 850 with a fully charged battery. A2 and A6
were
totally empty of codes both before and after the try. The car did
turned over
well but did not even cough. Half way through the 20 second crank I
tried some
Starter fluid into the intake. The Air Filter assembly was removed.
and the
MAF sensor disconnected. I was thinking about the possibility that the
FIMainRelay
being good but the wires to the same being bad. Below are the readings
I got.

Fuel Injector Main Relay Connector 4-Female .
Wires going out below page
____________
/ \
| 87 30 |
| |
| 85 86 |
| |
----------------

87 Thick Green
30 Thick Red
85 Thin Brown
86 Thick Red

With Ignition Off
-----------------

Wire To Grnd Volt To Grnd Ohms
87 0.0 1590
30 12.6 16 Meg
85 0.0 infinite
86 12.6 16 Meg

With Ignition ON
----------------

87 0.0
30 12.6
85 0.0
86 12.6

DVM readings done later with weak battery at 12.6 Volt

 

Hey guys I think I found something.
The 1590 ohms at pin 87 did not seem right.
I tested the resistance at pin 87 with the
ignition turned on, it read 2.6 Mega Ohms.
I don't know the specs for the fuel injector
current, but it would be a very tiny current
flowing at 12 V through that kind of resistance
- or am I looking at this wrong?
Where do I find the other end of the wire at pin 87
of the main fuel injector relay?
Thanks for much for reading.

 

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.

 

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.