Re: Bypass? No...I think my car need therapy!

["content22207" <brobertson@xxxx>]

Practice your troubleshooting techniques now, BEFORE Fall Foliage:

Remember -- there's a reason behind everything (and also remember:
every problem has a solution).

Start by jumping RPM relay. Insert a jumper between brown wire and
white/purple. This should cause pump to spin. If it doesn't, you've
narrowed problem to pump power supply or ground. Test for power at
brown wire (fuse 7 could be blown or not making contact). Test for
ground at pump itself.

If pump spins, test for resistance on air sensor plate. Plate should
not be totally floppy, and you should hear fuel literally squeak past
piston when raised. If air sensor plate behaves abnormally you're
probably not getting enough pressure to crack injectors. Could be bad
regulator in fuel distributor. If check valve on pump is bad system
could be full of air. Let pump spin for several minutes and see if
system pressurizes.

Make sure idle speed motor hasn't stuck closed. Use accelerator pedal
to open throttle plates. Don't bother pumping pedal -- no accelerator
pump. Engine could be slightly flooded from testing air sensor plate
above (you'll know if car finally starts and emits a cloud of white
smoke).

Test for ignition spark. Is a stretch, but center terminal on ignition
distributor is reachable behind/under fuel distributor. Pull coil
wire, push boot back to expose metal contacts, and place very near but
not touching the block. As engine turns over you should see high
voltage spark jump to block. Spark should be blueish or white, not
orange (low voltage). If you don't have a spark, start checking
connections from coil towards ballast resistors. White wire is primary
ignition voltage -- should be 8-10 volts. If you have a spark but is
weak problem could be starting relay -- run temporary wire from jump
start post to positive side of coil.

Note spark test can also be performed with a timing light (just look
for bulb to flash) or an ignition probe.

If you've got fuel and spark but car still won't start, check for
final delivery at the head. I usually use cylinder #3 because it's
easiest to access. Pop injector out of head, place in a coke bottle or
some such, and perform air sensor plate test. You should see injector
spray. Likewise pull spark plug wire, ground next to block (terminal
recessed pretty deep -- may have to extend beyond boot with a
screwdriver), and look for spark. Or test with light/probe.

Make sure you don't have a catastrophic vacuum leak. Supply line to
idle speed motor is 3/4" -- quite a lot of unmetered air if it's come
loose. Make sure cold start tube still seated firmly on manifold (is
visible between cylinders #1 and #2.

Make sure spark advance diaphragm isn't getting vacuum while starting
engine.

Since car misbehaves cold and hot, doesn't seem to be classic "hot
start problem," but is good to practice -- plug warm up regulator
(grey plug) into cold start tube. This will cause cold start valve to
spray extra fuel into engine no matter its temperature. If engine
starts, quickly disconnect cold start tube before engine floods.

While you're practicing -- try using a jumper to turn on headlights
("dipped beam") at relay socket. Is row closest to passenger seat,
relay closest to center of car. Locate two parallel terminals rotated
90 degress from other three -- line in is closest to outside of
socket. Line out is directly opposite on other side of socket (middle
of 3 remaining terminals). If you jump line in to line out, headlights
should come on. This will get you around a broken dash switch.

Try using same jumper to make cooling fans spin. First, pull
connectors off otterstat and jump together. Fans should spin as soon
as car energized (will get you around a broken otterstat). If fans
don't spin, leave otterstat jumped and jump relay just like headlights
above (same row, second from outside end). If fans STILL don't come on
you may have problems with whatever's plugged into fan fail socket
(next to fan relay), circuit breaker, or fans themselves.

Car has two mombo relays next to RPM relay -- Main and Accessory. Are
identical. Since car will run with main relay only, is possible to
swap with accessory if main relay fails on the road. Accessory
adjacent to RPM relay.

Should be enough to keep you busy for a while. Is best to practice
things like this BEFORE they're needed. Most car problems can be 
overcome temporarily.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "Kevin Abato" <delorean@xxxx> wrote:
> This is REALLY strange! 3 times in the past few months, my car has
> refused to start. See what you think...
> 
> The first time was a Saturday morning late spring: It had run fine for
> weeks, and was in the garage. It would not start. 2 hours later, (and
> much tinkering) it started fine. At the time I attributed it to a loose
> relay (it appeared to start after I checked all the relays behind the
> passenger seat)
> 
> 2nd time middle of summer: I was out driving for about a good hour.
> Stopped at my brothers house, and the car would not start again 40
> minutes later. After about an hour or more of tinkering with
> everything, it appeared to work better after having jiggled the intertia
> switch wire. It stalled several times just out of his driveway. The
> inertia switch plug seemed to be the key..jiggle one way, car dies.
> some more, car runs. I found a good "working spot" and stuffed the wire
> in place behind the intertia switch box. Car ran fine and continued to
> do so.
> 
> This past saturday: Car was in garage, had not been used for 2 weeks.
> WOuld not start. messed with inertia switch wire...no dice. (posted
> about ugly plug on the end of the switch, etc...) Decided to give it a
> rest unitl i read info on the DML. I was going to attempt to bypass
> the intertia switch tonight, but first i decided to try starting it.
> IT WORKS!
> 
> Keep in mind. NO bumps, vibration, nothing different had happened to
> the car.
> 
> I think it needs Psycho Therapy for having turned 20 or something!
> Anyone have any ideas or suggestions? I dont want to get stuck
> someplace (the the DMA fall tour) with a finiky car!
> 
> Kevin Abato
> Vin# 16680
> 
> 
> [Non-text portions of this message have been removed]