General rule, according to me:

You never assume that multiple symptoms are from a single cause. You can waste time looking for common denominators that don't exist.

The coolant warning is likely a bad coolant sensor. Please be sure you are identifying the correct icon on the instrument panel, I have had people tell me they had a low coolant light on, but were in fact out of windshield washer solvent.

There is a two wire connector for the low coolant sensor adjacent to the LH hood latch. Trace the wires back from the sensor, unplug it at the latch, connect the two wires on the harness side of the connector, and the icon on the dash should go out. Please note that this is a temporary fix: if you leave it that way, broken or bypassed as described, you won't know if your coolant ever gets low. That's the first warning you should get when you blow a coolant hose. And I bet you haven't changed the hose at the water pump inlet from the block, so one day you will need that warning light.

We don't know why the car is running rich, that has been your problem from the get-go. If you have not seen fuel pressure gauge readings over 40 PSI, you have ruled out high fuel pressure.

The pump relay operation, as you describe it, is wrong. That is the problem you need to trace, and once corrected you can prodeed from there. At a minimum, that takes an accurate wiring diagram, a testlight, brainpower and time. You likely won't find this problem unless you have all four, or bring it to Ohio and pay for the time.

Neither the relay operation you describe or the rich running condition are common fault symptoms for your car, particularly when no fuel fail codes are displayed. Track down the relay operation first. Sometimes you will end up finding a common denominator after all: have you looked at the ECU connections as I previously suggested? That's where the pump relay ground signal is coming from, wouldn't it be a treat if corrosion at that point was causing the spastic relay operation, and also affecting another connection which was altering injector pulse duration? Sometimes you get two for one, but you chase the one you can positively identify first.

 

Thanks JagTech!

I had a pretty major breakthrough today. Knowing that the relay was not functioning correctly, I decided to bypass it by bridging terminals 30 and 87 in the fuel relay terminal. It almost fixed the problem. I was able to drive the car about 10 miles (as opposed to 2 miles with relay in place), and when it did stall, i simply let it sit for a minute with pump still pumping, then it ran for another five miles (as opposed to 10 seconds with relay in after a stall)

So I've determined that it's a fuel supply issue, and when the pump is running constantly, it has enough fuel to keep it going for a while. Then when it runs out, it only takes the pump a few minutes to refill the fuel rail.

Knowing this, my first plan is to change the fuel filter. Would you suggest this as a starting point? Then I suppose a new pump, and perhaps build-up in the fuel lines could be a culprit? Sound good? Let me know!

 

Change Fuel filter only, road test car with gauge connected and set up so you can watch it. If you lose fuel pressure, change the pump.

 

OK It's been a while. Let me update/grumble. I replaced the fuel filter. I'm getting slightly better fuel pressure, but the problem is still there. In fact, after i changed the filter, it seemed to run worse, only running for 30 seconds or so before stalling. Since then (2 weeks ago) It's been pretty much the same as before. Pressure doesn't drop before stall (32-ish constant when idling), relay still clicks on and off. It does not maintain pressure after a stall, slowly drops to 5 psi or so.

So here's my next option: replace ECU, thinking it's a computer problem, or replace fuel rail, pressure reg's, and injectors.

I've checked out the ECU and all grounds look OK. Still slightly better when fuel pump relay is bridged. ?????????

Any advice is always appreciated!

 

Give me your ECU number, I'll send you one to try. The deal with the pump relay is not right.