[V8] V8 fails to start

[Ed Kellock]

Usually if it's a flywheel sensor it's just dead.  I suupose it's
possible if the sensor is just beginning to fail marginally, it might
be able to get enough of a signal to fire, but I don't think that's
ever been the case.

If it's trying to start but just not catching enough to do so, then it
could be fuel pump check valve not maintaining pressure in the system
when it's shut off.  My 89 200q had a problem with that.

If it's low fuel pressure there's not much you can do but wait and/or
keep trying to start it with the throttle closed.

Or, it could be the ECU coolant temp sensor on the back of the
passenger side head that is bad and telling the ECU to dump too much
fuel.

I simulated this over the weekend with my 1990 V8 by starting it
briefly and shutting down after a quick move in/out of the driveway...
 Sunday morning, I forgot and wasn't ready "catch" it and it flooded
and stalled.  I had to put my foot on the floor to keep the throttle
open and crank it until it cleared itself out.  It took a good bit
longer than I expected and there was plenty of gas smell to confirm
the problem.


There are two things you can try that may help isolate what is causing
your starting problem.  First, treat it like a flooded carburetted
car... hold the throttle open all the way and crank it a while to see
if it will clear out and catch.  Don't get too carried away with how
long you crank though.  Your really only supposed to crank for 10-15
seconds at a time in optimal condition.  I probably ran the starter
continuously for a good 30 seconds or more yesterday before I got it
going.  That was a bit long though.  I knew I was running the risk of
frying something, but I was lazy.  And lucky because everything seems
to be fine now.

A couple of years ago, there was V8 for sale locally that had a bad
temp sensor.  Me and a buddy went over and abused the hell out of the
starter trying to get it to start.  We actually started to fry a
connector somewhere in the engine compartment because we cranked the
starter so much.  After that connector was replaced or cleaned up
everything was fine and was still okay up until a couple months ago
when the car was sold again and I lost track of it.

The other involves pouring some water in a certain place to cool the
sensor and see if the engine starts.  Just keep a small bottle of
water in the car and when this problem occurs, pour some just inboard
of the driver's side distributor.  The water will run down the engine
where the sensors mount.  Usually a few ounces of water is enough to
cool the sensor long enough to let the engine fire.

I did this with the same 1990 V8 a couple years ago when the rpm
sensor failed.  The GF was out doing errands on a Saturday during the
summer and the thing just quit.  This will also prevent it from
restarting.  I went and rescued her and the car and had to repeat the
process 3-4 times before I could get to the interstate to get enough
airflow through the engine compartment to keep the sensor cooled off
so I could get it home.

Ed

On 1/28/08, George Verbryck <georgeverbryck at yahoo.com> wrote:
> I was out in the V8 yesterday and after shutting it off for 5-10 minutes it failed to start. Turns over great and you can hear it trying to start but just won't catch. Lately after it has been run i.e. it will start but stall if gas is not applied. This morning dead cold started fine and easy. Is this symptomatic  of the the fly wheel sensor? This is what I came up with after looking through the archives. If so has anyone bought these sensors recently and where, I know form the archive different  models have cheaper sensors but I could not find any part numbers. Many Thanks, George