E34 Touring (M50) Won't Start

[ClayW]

This is a friend's 1994 E34 Touring. I've changed the fuel filter for him, but to no avail. This is what happens when we try to start it:



Any ideas? Fuel pump? Fuel pressure regulator?

[e30austin]

Sounds like a classic case of "cranked it too many times with a weak battery" or something of the like. Seems like it has low compression.

I would pull all plugs, clean them well with carb or brake cleaner, dump a little bit of oil down each spark plug hole, reinstall plugs and try again. When it fires, it will want to die...do not let it die, it will be a pain in the ass to restart.

[ClayW]

What will that procedure accomplish?

If it's low compression, are we talking about a head gasket? Rings?

[e30austin]

What will that procedure accomplish?

If it's low compression, are we talking about a head gasket? Rings?

When you're cranking the motor with a weak battery (or whatever the case may be) for extended periods of time, the oil is getting washed off the rings and it causes a no start condition due to loss of compression. Dropping oil down the cylinders will get the oil back on the rings and build up compression again.

I've had this happen on a couple cars and have tried this little trick and it worked fantastic.

[ClayW]

Thanks! Will try.

What might have caused the no start condition to begin with?

[e30austin]

A weak battery (due to cold weather or other factors) is your likely culprit.