850 stalling/not starting: SOLVED

Hi, A few wks ago we posted the problem we were having w/ a '94 850
that would intermitently not (re)start when the engine was hot.Along w/
it just quitting while driving dwn the road too. We first tried
repalcing the plugs, then the distrtibutor cap/rotar w/ no luck. Along
w/ the spark coil and the RPM/Impulse sensor as recomended by a couple
of folks here. So we finally decided it was time for a visit to the
dealer. BIG mistake,,,. We got PORKED to the tune of over $600 for a new
fuel pump. Hey like the car has less than 200K mi on it,,,. The very
next day,,, the SAME problem again... But the fuel pump did give me the
idea to check what was CONTROLLING the pump,,. This came to mind after
recalling how the fuel pump relay on my old 240 had given me fits,,. It
took a few to ID exactly where the fuel pump relay/controller was
located, but we found it under the cover for the fuse holders; Its the
big, green, square one, marked "103". We knew we were on the right track
when we got the engine to die whenever we tapped on the realy a few
times,,,.

We pulled the relay and snapped off the cover. Althought the contacts of
the relay itself looked ok( we gave them a quick burnishing though), I
could CLEARLY see on the small printed circuit board where the relay was
mounted, what would be described as "cold solder joints" on the two
pins/leads from the realy's coil. At least it wasn't as burnt up as the
circuit board on my 240's relay,,. We proceeded to carefully "reflow"
the connections w/ some fresh solder, then reinstalled the relay. That
was two weeks ago, and Im happy to report, NO further problems! While
doing an oil change on my other 850( a '95), we decided to check its
fuel pump relay too. Even though Ive had no problems, so far,, we DID
see evidence of the SAME type of problem. So as a prventive meassure, we
resoldered the relay connections there too.

For most "gear head" types(no offsense,,), I would recomend simply
relacing the relay. However if you are handy w/ a soldering iron, you
might also want to fix the old one and have it handy as an emergency
field replacement,,. You would want to use a 40-50 watt soldring iron w/
a grounded tip as the circuit card has a 4538 logic chip on it. I
suspect the chip's function is as a timer to energise the relay during
initial startup.(?)

Apart from the cost, what iritates me about my experience at the
dealership is how they apparently diognosed this problem by replacing
the first(and most expensive) thing the mechcanic saw fail. INSTEAD of
trying to further isolate the problem. Given the degree of electronics
in vehicles these days(it would seem) that if mechcanics were trained to
think more like electronic techs, they would be far more effective in
isolating intermitent problems of this nature. I also wish that Volvo
could find/use relays that didnt burn up over time; I noticed that while
troubleshooting this problem that besides the fuel pump relay getting
hot, the 3x "J" relays were also getting hot too. I previosuly had one
of the J relays go on my 95 850 a few yrs ago. Could someone please tell
me what EXACTLY the 3x "J" relays do, so I'll know what to check when
this or that doesnt work,,,.

Cheers Steve

 

I've done the same, and this is why I won't be buying any new Volvos.
Their service manuals exist only in the form of online "subscriptions"
and a grossly-overpriced DVD set. Volvo wants to make it impossible
for me to work on my own car, so I'll buy another brand next time.

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The fuel pump relay is a well known fault on 850s.

For something of that nature and cost, I would have asked them to get
my permission before spending $$$...I would also want to know if there
was any other part that could fail that would appear to be the fuel
pump....then you would have recourse to claim costs back if they
change a fuel pump and the problem still exists.

The real problem I see is that the vehicle technicians are now trained
to just read off computer codes, and fix that fault.
They don't seem trained to fault find themselves, or even to think
outside the script of what the computer tells them.

In this case, the fuel pump or relay wouldn't even log an error code,
so you're relying on someone who knows the foibles of an 850...here in
the UK my local Volvo dealer knows appears to know bugger all about
850s and the 'usual' faults.

 

Hey all

My 83 850GLT is doing something similar and I am wondering if I have tthe
same problem.
I am a "Computer guy" and I understand how temperature differentials can
cause soldering and circuits to
eventully fail due to repeated expansion and contraction.

'bout 3 weeks ago it was very hot outside and the engine would crank just
fine but not light up.
After two days of head-scratching I tried again and tadaaa, it started just
fine, and ran up until yesterday.

The night before last the tempature outside dropped from 85 degrees F, to 45
degrees F.
Once more, the engine turns over but will not start.
I want to check the fuel pump relay as you did, is the '93 850 similar?

I'm also wondering about fuel filters maybe getting fouled. I have never
replaced and have no idea where
they are. Must get Haynes manual I guess.

Any tips or suggestions would be greatly appreciated.
Thanks for consideration!