Engine

Engine Cut-Out

This morning on my commute to work the engine completely cut-out twice! The first time I was
about 10 miles into my drive, when out of the blue it felt as if I lifted of the gas (going about 75
mph at the time). I re-acted by trying to give the car more gas - but nothing! Coasted off the
highway and it died before coming to a complete stop. Tried re-starting to no avail. It was
turning over fine, just no start. After about 5 min. of trying - Bang - it fires right up, like nothing
happened. No sputtering, nothing weird sounding, nothing!!!!
So, I take off again and continue my drive to work. Then about 5 miles later, same thing!!! Just
cuts-out, like I turned the key off or something? This time it take about 30-40 minutes before it
restarts. Once again, I get back on the road and continue my commute. I make the rest of the trip
(about 15 mi.) with no problems. Anybody have any ideas as to what's going on? Could the
fuel pump start and stop working like this? The fuel filter is new. Can the relay act up
intermittently before going out?
Help!!!!! I have to drive this beast home!!!!!!
*Dana '85 928S

Response #1
Sound like the classical symptom of a bad fuel pump relay to me!
You wont be able to find a replacement part at Radio Shack. You'll have a better chance at an
import parts store instead. The relay has electronics in it. Volvo and Mercedes uses the same
part. Bring your original relay in to match. Actually, there's a good chance that you can
resurrect your old one. Pry off the relay cover box and look on the underside of the printed
circuit board. You'll probably find a few cold solder joints; specifically the pads that goes to the
relay frame's body. Just resolder it and that should fix it. You need to use at least a 50 watt
solder gun. Try your local TV repair shop for a quick resolder; they might do it for free! You
might want to check on the contacts as well but generally they're quite durable. Whatever you
do, DO NOT FILE THE CONTACTS! If you can't clean it, then trash it.
To lessen the damage done by the voltage arcing, some relay manufacturer uses a special alloy
on the contacts. If you damage or remove it by filing, the lift expectancy of the contacts are
reduced dramatically; pitting will occur at a much faster rate. This is especially the case in area
where high-amperage draw is frequent and continuous. eg. fuel pump, anywhere from 6-10
amps at 12 volt.
*Vince Yu
'83 928S
'78 928

Response #2
I had a problem that sounds identical to yours. In my case, the problem was the relay that gives
power to the electronic "brain". I took out the relay, opened it up, and found that one of the
solder joints inside had become cracked. I soldered it back, but replaced the relay later with a
new one just to be sure. That was two years ago, and no problems since. It took me a couple of
months living with the intermittent cut-outs before I figured this out. Good luck.
*David Leith
'87 S4 5-speed

Response #3
Check and clean the various grounds on your car. I had a similar problem with my 83' 928, it
turned out to be a fuel injection ground. This ground is located in the engine compartment on
the passenger side, by the valve cover. (if I remember right). good luck
*Randall