[DMCForum] Re: very frustrated!! - starting problem

["cruznmd" <racuti1@xxxxxxxxxxxx>]

Ah, good question. Sorry :)

At the inertia switch, you need to do a "continuity" check. The 
ground wire from the fuel pump is black/purple, it goes to the 
intertia switch. Clip one ohm meter probe to the ground wire on the 
pump, then clip the other one to the black/purple contact on the 
intertia switch plug. If it reads "open" your fuel pump is grounded 
elsewhere and you need to find it. It's probably fallen off. If it 
reads "short" then the b/p wire is attached to the harness as it 
should be.

Also, inspect the BLACK wire on the inertia switch plug to make sure 
it's grounded properly. Just touch the one probe to the black wire 
contact and the other probe to the body or frame somewhere. Again, 
short=good, open/resistance=bad. If the pump is grounded at the 
switch but the -switch- ain't grounded you'll still have the problem. 

Lastly, (regarding the inertia switch) remove and inspect the black 
box. Look at the contacts. Is the plastic melted around them? The 
older style were a point of failure. They were underrated. You can 
also put your ohm meter on the contacts and pull the plunger to make 
sure it's operating properly. Plunger down= short. Plunger up= open. 
This is the correct mode of operation.

I'm really pushing this grounding issue because you jumpered your RPM 
relay and still only had 00.00 volts (flashing 7v). That clears the 
relay from the problem. BTW, I think your jumper was probably fine.

Oh hell, I just remembered. DeLoreans use the European habit of 
switching grounds on and off, not power. Definitely follow the steps 
above, but also jumper the RPM relay again, and measure for 12v on 
the white/purple wire but do it with a ground OTHER than the ground 
wire on the pump. Use the body or frame somewhere. 

If you have no voltage, go back to the inertia switch and touch 
white/purple, and an independent ground again. (Frame/body).

If you have no voltage THERE, go back to the RPM relay and do it 
again! Unplug the relay and touch W/P and an independent ground. The 
seat belt mounting bolts make a good ground I think. You're tracing 
the flow, finding the break in the pipe.

Electricity is just plumbing. Electrons flow instead of water and the 
pipes are really tiny.

Post your findings when you can.

Rich A.
#5335

--- In DMCForum@xxxxxxxxxxxxxxx, "Brian" <TK581@xxxx> wrote:
> > Ok, two or three people have told you where the interia switch is.
> 
> What exactly am I supposed to check here?  It's pluged in and it's 
a 
> black box... :)
<snip!>

---

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