94 850 t come and go gremlins

kyles850 · Post by **kyles850** » 03 Jun 2009, 22:26

Hi ,I am a new member.
I have a 94 850 turbo wagon that runs great, but sometimes when I go to start it, it just turns over and won't start.
The first time it did this, it fired up and ran perfectly the 3rd time I turned it over.
A week of diving it daily with out issue, and suddenly again it will only turn over.
After many tries, I open the hood, I first check the fuel rail, good fuel pressure there, I then check all the vacuum hoses and elbows,
I disconnect the battery for a couple minutes and wiggle every connection I can see. But nothing.

I then go into the back seat and fold them down so I can listen if the fuel pump is running when I turn the key on.
I hear it priming and decide to try turning it over again, bang it starts right up. So I guess folding the seats down helped somehow.
I get the car home, shut it off and try and start it right away while its still at running temp, thinking maybe cold start is a factor,
but she wont start.
The onboard code reader does not work, I can't even get a 1-1-1
the red light comes on when I push the button but thats it.

Over the next few days the car starts when it wants to right away,, about 3/4 of the the time cold or hot, the other 1/4 its temper-mental but will not give me an indication of which sensor or relay is failing. but when It does start, its always as soon as I turn the key.

So far I've changed the fuel pump relay, fuel pump and fuel filter and the mass air flow sensor, I've checked the distributor and the wires, all looks good.
When its starts it runs perfectly. So what have I missed?
I have had this volvo since 97 and its been trouble free, till now,
Hope someone can help ,, thanks Kyle

STEVE DELA MONTAGNE · Post by **STEVE DELA MONTAGNE** » 03 Jun 2009, 23:56

I currently own 2 x 850's - - one is a high Km early model ( 330,000 Km's ) which still goes like a smokey-train - - the other is a mid life version 237,000 Km's - - - the problem you describe could be any of the things you mention already - -and a good few more - -but if you have tried all the usual ones ?? - - then check the two large computer cards in the Air cooled Plastic Box - - attached to my front right inner wing ( on an Australian Model ) - - there is a slim Duct connecting the mounting box to the Radiator - - and the lid must be removed carefully so the cover clips aren't damaged - - - - . I must admit I am not next to the car - - so check your Manual about removing the box lid carefully . - - then I found that my similar problem was solved by removing each of the large computer cards ( only after the car ignition was turned off! ) - - each card removed very carefully and the connectors on the lower side of the card checked for debris ( Lots of dust - -and i suspect a dried out joint in evidence !! ). I would recommend earthing yourself to the car when you are removing the cards ( touch the metal part of the car body with a sweaty palm ) .

I removed each card carefully and Air dusted the mounting points with the air blower I have in my garage ( perhaps carefully vacuuming in the mounting box will help ).

Take care and best of luck - - my fault did not recur - -but I suspect you will need to use the "remote" to reset the security before a satisfactory restart . ( The car ran well for a further 20000 Kms after - - its about to die from terminal Ring Blow By - -hence the newer mid life version ).

kyles850 · Post by **kyles850** » 04 Jun 2009, 00:26

Thanks for replying. I love the blue mountains but its been over 15 years since I've been to Kurajong pub.

I have 2 sets of e.c.u.s for my 850 t,my original and one out of an R, and I've tried switching back to my original one just to see, but It did nothing.
I will try and clean out the box as you mentioned, thanks again,,
have a V.B. for me, the ones they import here to Canada don't taste the same, cheers Kyle

Post by **Ozark Lee** » 04 Jun 2009, 21:55

Kyle,

Try pulling the codes from the OBD-II port under the coin tray. The pushbutton on the OBD-I port is subject to corrosion which leaves it inoperable. Your car should have both ports since it is a turbo.

FYI, the OBD-I box comes apart easily and some contact cleaner on the pushbutton contacts will often bring the OBD-I reader back to life. There is a spring that will want to go flying but if you remove the upper housing carefully it is an easy DIY fix.

...Lee

kyles850 · Post by **kyles850** » 06 Jun 2009, 00:31

Thanks Lee,, it does have a connection behind the coin tray.
I will try cleaning up the one under the hood. Right now the gremlin is away, so the car has been starting no problems the last 20 times or so. I just hate the feeling of not knowing if it will start each time, Kyle