'89 Caravan Won't Start

3 liter six cylinder, 115,000 miles.

Symptoms: Turns over fine but doesn't try to start. Started and ran fine
when I drove it home from work last night.

So far I've tried:
Check trouble codes with the Check Engine light method. No codes stored;
55 was the one and only message.

Checked cap and rotor (about one year old), both showed wear but looked
adequate.

Tried disconnecting MAP sensor. No change.

Checked spark at distributor end of coil wire; spark looked good. This
rules out the auto shut down relay (ASR), right? Or does the ASR only shut
down the fuel?

Sometimes when I turn the key I hear the fuel pump running for a few
seconds, sometimes I don't. How long, typically, will the system stay
fully pressurized with the engine not running?

Gas gauge said 1/2 tank. Just to be sure I walked to the nearest station
and brought back a gallon. Put 9/10 of it into the tank. No change (still
wouldn't start), although the gauge may have moved up a little. Poured a
few ounces into the throat. Motor started immediately and ran until the
prime ran out.

So obviously, it isn't getting fuel.

Does the lack of a stored error code rule out the throttle position
sensor? I have an analog multimeter, but the Haynes manual doesn't say how
to test the TPS. Can anyone tell me how to do that?

Also, is the fuel filter that is mounted to the frame under the van the
only fuel filter, or is there another fuel filter under the hood?

 

Comments inline.

Excellent. Not many know to do this.

The ASD relay controls both the fuel pump and primary voltage to
the ignition coil (and more).
So, yes, this rules out the ASD relay.

Ideally, a long time, easily overnight if not longer.

The TPS has three circuits;
5 volt feed
return signal
ground
I'd love to be able to give you wire colors but my laptop is at
work.
Using a straightened paper clip or largish sewing needle, back
probe alongside the wire going into the TPS connector until
contact with the terminal inside is established, connect you
voltmeter negative lead to battery negative, key on engine off
you should read 5 volts on one wire(5 volt feed), appx. one volt
on another wire (return signal) and zero volts on the third
(ground) wire.
An open ground will result in a full five volts on the signal
return, an open 5 volt feed will result in zero volts anywhere,
an open in the signal return typically can't cause a no fuel
condition.
If you're unfamiliar with back probing, see the picture(s) at:
http://www.aeswave.com/products/Product.asp?i=161&ci=6&sa=Y
Switch your meter to ohms, only the ground should show continuity
(low ohms) with ground.

Other than the in-tank strainer, it is the only fuel filter.

I think you really need to measure fuel pressure.

 

Thanks for the info. It rained today so I couldn't work on it (no garage)
but I will check that on Sunday when I'm off.

You're right about that. But first I'll try taking the fuel filter off,
and unless it it very open I will try my luck by replacing it. If that
doesn't do it, it is time to invest in a fuel pressure gauge.