Chrysler Repair: 91 Voyager 3.3L fuel supply problems, fuel pressure regulator, vacuum hoses

Question
QUESTION: Roland,

I am troubleshooting my 91 Grand Voyager (3.3L, ~230K miles) that suddenly one afternoon would not start.  Upon leaving work, van fired up but died a few seconds later.  Over the next few hours I kept trying to start it but the van would not start.  Had it towed home and started tinkering with Crankshaft and Camshaft sensors.  After replacing and/or testing both sensors the van still will crank but not start.  Changing directions, I give the air intake a little starting fluid and it started and ran pretty smoothly for a few seconds.  This has me thinking fuel system.  I replaced the fuel filter last night to no avail.  When replacing the filter, I went to bleed of the fuel line pressure at the rail and there was no pressure at all left in the system.  It is my understanding that the Fuel Pressure Regulator runs off of a vacuum, I looked for a obvious problems in the vacuum hoses but did not see anything.  Suggestions on where else to look for a problem that would cause a vacuum problem to manifest itself in the Fuel Pressure Regulator?  To my knowledge, the fuel pump, strainer, pressure regulator, etc are all factory original parts.

I tried to follow the wiring harness for the fuel pump but could not find it.  On the right side (passengers) I have the three fuel lines but no wiring harness, on the left side I have brake lines but still did not see a wiring harness.  Does it lay inside a frame rail or something like that?  What are your thoughts on what part(s) to look for repair or replacement.  Fusible Link (where)?  Fuel Pump?  Pump Strainer?  Fuel Pressure Regulator?

And as a related question, do you know what the 5 relays are for on the inner fender walls?  I have 3 on the left side (drivers) and two on the right.  All the books I have read (Hayes 84-95 book and 94 factory service manual) reference 4 or 5 on the left.  It appears that the 91 year had a different layout but I cannot find any reference to what relay does what.

Thanks


ANSWER: Hi Matt,
Before going into the details of the fuel system, regulator, harnesses, I would suggest that you try to readout the fault codes from the engine controller. I had an identical situation brought yesterday and here are the specifics:
Use the ignition key:"on-off-on-off-on and leave on" doing that in less than 5 seconds elapased time. Then watch the check engine light which stays "on" then begins to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the whole process to be sure you have an accurate count of the flashes. Then write back with the results and we'll go from there. Use the "thank/rate" tab to get to me without having to wait for me to be 'available' for a question. There is a space for comments.
On the new sensors, did you push them in far enough for the tips to contact metal surfaces that they are designed to "sense". The paper spacers on the tips are there so that when the surface spins the paper will wear away but leave the sensor close enough to the surface to detect the cut outs as compared to the surface. If you didn't put them in all the way then you may not be getting the signals you need to make the spark.
After you are sure you have an accurate fault code count, disconnect the - post of the battery clamp for a few minutes, then reconnect it, they try to start the car again. Then re-read the codes and see if there are any differences. The codes you read first are "stale' but relevant, while the new readout is up-to-date. Tell me both results.
On the relays: the two on the right side are the back-up lamp relay and the transmission shutdown relay (puts the trans in limp mode if 'open') while the left side front to back are the engine asd, a/c clutch, radiator fan, and starter on the strut tower. Also, check to see if you have spark when you crank the engine and also listen for the sound of the fuel pump running inside the fuel tank when you first turn the key to the "run" position. It should run for a couple of seconds and then fall silent, then start again when you try the starter motor. Have helper at the ignition switch while you listen at the rear of the van for this sound.
Roland

Thanks for the quick reply. First thing I tried was the codes, I have got 55 since the problem started. I have NOT disconnected the battery and cleared the computer yet but will try that when I get home. When I replaced the sensors, I did make sure the paper spacers were in place. Before trying the starting fluid, I used a ignition tester (mostly used for small lawn and garden engines) and it showed spark on all cylinders. I have only heard the fuel pump once since the problem started. That was about 3hrs after the problem started. The van started but died a few seconds later. At that time I was not sure if the overall problem was related the high 90 temp so I did not think much of it. I have not heard the fuel pump since.

Hi Matt,
My suspicion, if you haven't noticed the fuel pump for that brief humming sound, is that your pump is not working. So recheck that. It is powered by the ASD relay which also powers the spark coil, injectors, oxygen sensors, so if you have spark but not pump action it has to be the pump, or the wire from the ASD to the pump is 'open' (dark green/orange).
Thanks for the evaluation and nomination.

---------- FOLLOW-UP ----------

QUESTION: Where does the fuel pump wiring harness run from?  I wanted to pull the connector on the supply side (under the hood somewhere?) and test for voltage.  I tried to find the harness under the car and trace it back but all I could find were brake and fuel lines.  Does the harness run in the in the frame rail?  Or am I just missing it?

Answer
Hi Matt,
The manual I have doesn't show the details of the harnesses, but you could start at the ASD relay socket (dark green/black* wire) and check for continuity to a plug at the area near the tank. There is a 4-wire connector nearby that couples the harness from the front to the pump and fuel gauge and ground. The other end of the dark green/black is located there so that would prove out whether it is the wire or the pump.
*sorry I miscalled the coloring of the ASD 12V output wire; the orange trace is used on some of the other models in that timeframe, I was going by my memory.