kiromarc

My old 740 keeps cutting out, one moment it is fine, next nothing, the
engine just stops in an instant, kinda dangerous when the PAS and PAB
stop! Ive replaced the coil and HT leads, no change !!! Any ideas anyone
out there?

Boris Mohar

On Fri, 11 Mar 2005 09:26:44 -0500, "kiromarc" <martineau.family@virgin.net>
wrote:

>My old 740 keeps cutting out, one moment it is fine, next nothing, the
>engine just stops in an instant, kinda dangerous when the PAS and PAB
>stop! Ive replaced the coil and HT leads, no change !!! Any ideas anyone
>out there?

Fuel pump relay probably. Take it out, remove it out if its case and
resolder the connections on the small circuit board that contains two relays.
Next, clean the relay contacts with fine grit paper. Glue two pieces back
to back and cut a small strip from that. It should be stiff enough to insert
between the contacts. The contacts that are situated in the center of the
board are pump contact and see most of the wear. If you are really diligent
you can unsolder and swap the two relays.

Could be the Hal sender also.





Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

Stewart Hargrave

On Fri, 11 Mar 2005 09:26:44 -0500, "kiromarc"
<martineau.family@virgin.net> wrote:

>My old 740 keeps cutting out, one moment it is fine, next nothing, the
>engine just stops in an instant, kinda dangerous when the PAS and PAB
>stop! Ive replaced the coil and HT leads, no change !!! Any ideas anyone
>out there?

Common problems are the Hall Effect unit in the distributor, and the
fuel pump relay behind the fuse panel.

Both the brakes and steering will keep working, but they won't have
any power assistance - you need to work harder at them, but they don't
stop.
--

TSH


For email, replace 'SpamOnlyToHere' with my initials

Michael Pardee

"kiromarc" <martineau.family@virgin.net> wrote in message
news:6747c11d9458a7e1e6f95f2a696dbc57@localhost.talkaboutautos.com...
> My old 740 keeps cutting out, one moment it is fine, next nothing, the
> engine just stops in an instant, kinda dangerous when the PAS and PAB
> stop! Ive replaced the coil and HT leads, no change !!! Any ideas anyone
> out there?
>
If it truly stops in an instant, and the tach plummets like a stone, it is
almost certainly the ignition rather than the fuel.

Besides the Hall effect sensor in the distributor, I understand there is a
radio suppression relay in the ignition circuit that can become
intermittent. I've looked for mine a few times since Mike F mentioned they
can be trouble, and for the identical relay beside it that can be swapped
for troubleshooting, but I haven't actually seen them... or looked very
hard.

The "power stage" mounted to the fender above the battery is also a frequent
complaint, but most people report a more gradual loss of power rather than a
switch-off. If you get bored or ambitious or desperate you can unmount it,
clean under it and remount it with silicone grease (I like the dense white
"heat sink compound" electronic and computer stores carry). I don't know if
they ever actually fail completely, or just overheat and get tired of
working.

Finally, it's worthwhile to clean up the battery terminals. If that separate
ring terminal on the positive post doesn't make good contact the engine will
cut out just as you describe. I scrape it every time I clean the posts.

You'll probably do the easy things and leave the more expensive Hall effect
sensor for last. The sensor is hard to pin down as the cause because they
typically fail on their own schedule. A replacement from a wrecking yard may
be an affordable alternative.

Mike