PetesPonies

Low mile delSol, 88K. It was sitting about 3 weeks, went to start, it wouldn't start. First thing I did was check for fuel pressure; none. Went online, found information about the main relay, fuel pump and injectors . .seemed like maybe my issue. I looked for testing procedures and tested my relay. It failed the first test. This was energizing #8 and 36 terminals. No click, nothing happens. I went and tested the other two combos, #5 and #2 . .nice solid click. tested #3 and #8, nice solid click., Back to #8 and #6, nothing. OK, ordered a relay. The correct relay showed up, no #4 terminal. Plugged it in, same problem. No fuel pump coming on, no pressure. So I tested the new relay . . it failed the same #8 and #6 terminal test. Huh?? So I think I must have read some bad info or?? Can't be a faulty replay to start ( shouldn't be ). Thoughts????

PetesPonies

Did more. I jumped the black/yellow wire with the yellow/green and the fuel pump came on. So my pump is good. My wiring to the relay and to the pump is fine. It stills eems like I have a bad relay . and it's new smh

mk378

The way it works, the ECU grounds one of the small wires (I forget which number) which closes the relay and starts the pump. Or, when the key is turned to start, the starter signal circuit energizes one of the wires which closes the relay and starts the pump. This is not going to let the engine start if the ECU is dead though. If you're sure the main relay and power and ground circuits are good, yet the CEL stays on constantly and the relay control wire from the ECU never goes to ground, it's a bad ECU. Additionally an ECU that doesn't boot up won't spark the plugs either. Sometimes if you leave the key on for several minutes, the fuel pump will eventually prime and the CEL goes out and then you can start the car. Again if that is not the main relay its a bad ECU.

Still I would open up the relay and resolder it just for kicks. The OBD1 main relay is known to always have cracked solder problems, and a new part isn't necessarily good.

PetesPonies

If I spray fluid, it runs. There is ignition. I believe the ECU is working. Here's the deal, was the test I was given a good one? Because the old relay and new relay are both testing bad. That is energizing the #8 terminal and completing it with the $6. I hear nothing, no click. It test says it should. If you look at a diagram, #8 and #6 are the winding for one of the relays The control circuit ). You energize that electromagnet through #8 and #6, it should pull in the controlled circuit, hear a click. All solder joints on original relay are good. I used to teach soldering, these are fine.

PetesPonies

Just went through through the diagram and #8 and #6 were backwards in the write up, as far as polarity goes. Time to retest.

PetesPonies

So the mystery gets deeper. I was correct in that the #8 and #6 terminals were reversed in polarity from what I read. After seeing the schematic of the relay, #6 is obviously the positive terminal. When I hooked it up that way, it worked fine. And that was the original relay . so I put it back in the car, turned the key for grins and giggles and . . it started. Only thing that was really done was the pump was turned on for a send or so, without any help from the ECU or the relay. SMH !! Many many times throughout the years of teaching and doing restoration and such . . . . I have taken things apart, put them back together and they work. This is either my lack of ability in seeing the problem or my ability in returning things to the way they are supposed to be. Either way, it leaves a query , an unsettled feeling. I would rather know exactly what changed. Now I'm not calling this fixed, lets see how it does tomorrow and the next and the next and . . .

PetesPonies

I started it several times yesterday. Tried it today, no fuel pump again. It hasn't been hot, nice cool day.

strategy400

Any update?

PetesPonies

Bought a used ECM for cheap, plugged it in and that was it.