850 no spark no fuel

eboknight · Post by **eboknight** » 14 Feb 2009, 19:42

I am working on a 95 850 wagon, it does not have fuel or spark. I have replace the coil and cam sensor no help. I have checked the injectors they are not firing. Once and a while disconecting the battery for a while will let it start but as soon as you turn it off it won't start. Before this started it was ran very low on oil. I'm out of ideas any help would be apreciated.

Post by **Ozark Lee** » 14 Feb 2009, 20:30

Welcome to MVS eboknight,

When you say you have no fuel do you mean no fuel pressure or the injectors don't work?

The master fuel system relay which is on the driver's side of the fan shroud is key to the injectors.

We have a link to a full, 1995, factory service manual that may help you. The link changed to another host and it is slightly spammy but here you go:

http://www.savefile.com/files/2001813

The problem sounds electrical and I noted that you changed the cam position sensor. Did you check the connections at the RPM sensor? They need to, for the most part, agree for the engine to run.

You have on board diagnostics on a '95. Pull the codes from port A-2 and post any of them that you have back to the thread.

The very low on oil part sounds scary but it shouldn't prevent fuel and spark.

Let us know what you find.

...Lee

eboknight · Post by **eboknight** » 16 Feb 2009, 21:02

I bypassed the fuel relay and the fuel pump is running, I did not check the pressure at the rail I need to borrow a pressure gage. I also disconnected the maf sensor, did not remove.
Will it run with the fuel relay jumped or does it have to be put back in. The connections look fine on the speed sensor, but the thing with sensors they can look good but junk. Is there any way to test the speed sensor.
Thanks for the help.

Post by **Ozark Lee** » 17 Feb 2009, 08:26

Will it run with the fuel relay jumped or does it have to be put back in

Yes, it will run jumped. If the pump is running then chances are good that the fuel pressure is fine. Have you checked the connections on the master fuel system relay? It is more exposed than most of the relays on the car and I have seen corrosion problems.

The speed sensor should put out 4 to 7 volts at idle, 0 volts with the engine not running. It is an AC signal.

Is this a turbo or an N/A model?

...Lee

eboknight · Post by **eboknight** » 17 Feb 2009, 20:24

It is not a turbo model. I checked the master relay and it looks good. I can't check the speed sensor running would I get a reading when the car is cranking. I looked into it autozone gave me a crank sensor not cam so that is what I replaced. Do you think it could be the cam sensor and is there a way to test that.
thanks for all the help

Post by **Ozark Lee** » 17 Feb 2009, 20:42

The cam sensor will kill you dead in your tracks. Unless you have an oscilloscope laying around I know of no way to test other than known good. You might be able to see voltage bumps with a VOM on a good one. It is a hall effect sensor that will bump from battery voltage to zero along with the cam rotation.

If the cam sensor just up and dies it won't throw a code since it waits to compare the RPM sensor with the CPS sensor for conformity after the engine is running before it decides it isn't happy. If the engine doesn't run it never makes the comparison - it just gets confused. The cam sensor controls everything, spark, fuel injection, and timing.

Sadly, they are pricey little b*stards. I've seen a couple of threads where folks have just changed the hall effect sensor inside of it for considerably savings but I can't put my hands on the links at the moment.

...Lee

eboknight · Post by **eboknight** » 18 Feb 2009, 17:53

As far as I can figure the cam sensor is the problem I'll probably shell out the money to get a new one. I'll let you know what happens.
Thanks again

bistrohenry · Post by **bistrohenry** » 20 Feb 2009, 09:38

Did you replace the RPM sensor?
My daughter's car has a similar symptom.
https://www.matthewsvolvosite.com/forums ... =1&t=18855

My mech read code for me and there were mis fires and crank.rpm sensor codes.
By the way disconnecting MAF sensor seemed to work, but it was temorary insanity.
I am waiting for a sensor from fcpgroton.
The fun is always fix one, wait, fix the next....
Thanks,
Henry

eboknight · Post by **eboknight** » 25 Feb 2009, 17:33

Well I changed the cam sensor it started and ran fine, soon as I shut it off it went back to the same thing. When it ran and did not start afterward I realized I had left the rpm sensor unhooked I pluged it back in and tried it again no change. My best guess is replace the rpm sensor and see if that gets it.
Any other ideas please its always apreciated.

bistrohenry · Post by **bistrohenry** » 25 Feb 2009, 19:47

Car runs better with a warm up in temp.
My guy was going to do some diagnostic checking for me... 1 hour limit.
Replaced rpm sensor. Seemed better, than crapped out after 20 miles.
Car starts, runs for anywhere from 20 to 120 seconds and then just dies.
He is leaning towards fuel pump relay.
Makes sense... ?