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matthewjr77 · Mar 4, 2009, 09:28 PM

The car stalled while driving. Suspected fuel pump problems, so I listened for the 2 second fuel system prime. I could not hear the system "whirring" sound as described by the manual. I followed the prescribed T/S steps. No voltage present at the pump during the 2 second priming stage. Next, I checked for a 12v input into the EFI main relay and there was 12v present. Then, I checked for a 12v input into the circuit opening relay (COR) with the key in the "on" position, and it was present. When I plugged the COR back into the jack I could not feel the relay energize in the "on" position. I could feel this relay energize when I turned the key to the "start" position, however. I jumped the "+B" and "FP" to bypass the COR and the pump ran continuously.

I believe the COR is bad, but a replacement part is over $100. Can someone please help me?:confused:

kitch428 · Mar 4, 2009, 10:08 PM

I can truly say I have never seen a fuel pump problem on a corolla. (25+ yrs)
I would be looking at the coil if I were you or ignition related.
Everything you stated about pump has "normal" stamped all over it. COR is energized only with key in start pos. As for all Toyota's.

matthewjr77 · Mar 4, 2009, 10:36 PM

Originally Posted by kitch428

I can truly say I have never seen a fuel pump problem on a corolla. (25+ yrs)
I would be looking at the coil if I were you or ignition related.
Everything you stated about pump has "normal" stamped all over it. COR is energized only with key in start pos. As for all Toyota's.

Well, I think after 25 years you still haven't seen a fuel pump problem. The pump, when the jumper is in does work. As far as the COR energizing only when the ignition is in the start position, I have a schematic in front of me that indicates otherwise. Additionally, the T/S steps in the manual indicate that it is energized in the "on" position. I have a scanned copy of the schematic in pdf format if it would help to see it.

There are two coils in the COR. One appears to be energized after the EFI relay and the other is energized after the starter relay. Thanks and keep the suggestions coming.

Sincerely,

Appreciative

kitch428 · Mar 5, 2009, 07:39 PM

eng7at.pdf

This should help you out some more. Scroll down to page 70 in the pdf. See C7 pin 1-2
This is the factory EWD.

matthewjr77 · Mar 6, 2009, 08:58 AM

Originally Posted by kitch428

eng7at.pdf

This should help you out some more. Scroll down to page 70 in the pdf. See C7 pin 1-2
This is the factory EWD.

Thank you for the great diagram. I have a few more questions.

I now see that the COR is made when the starter is cranking, but what about the 2 second prime signal. Is that input (the one coming into pin 4 of the COR) from the ECU, and could the ECU be the problem? Remember, the 12v required for the 2 second prime is not present. Is the 2 second prime controlled by the ECU or by a pressure sensor?

kitch428 · Mar 6, 2009, 04:36 PM

I don't know where you're getting this information you stated in your first 2 sentences of your op.
This is symply not true on Typical Toyota's such as yours. Honda, yes, but not a Toyota. The fuel system holds fuel pressure at all times by way of a check valve in the pump.
This will explain how the system works.
Fuel system circuit.pdf

And if you still want to keep checking that COR, then here's a great diag.
circuit opening relay.pdf

Once again, If were me, I'd be looking at the ignition circuit.

Regards.

matthewjr77 · Mar 6, 2009, 10:01 PM

Originally Posted by kitch428

I don't know where you're getting this information you stated in your first 2 sentences of your op.
This is symply not true on Typical Toyota's such as yours. Honda, yes, but not a Toyota. The fuel system holds fuel pressure at all times by way of a check valve in the pump.
This will explain how the system works.
Fuel system circuit.pdf

And if you still want to keep checking that COR, then here's a great diag.
circuit opening relay.pdf

Once again, If were me, I'd be looking at the ignition circuit.

Regards.

OK, OK... you got me. If I've learned anything in my time, it's that I should listen to the voice of those more experienced than me. Before I continue, let me say thank you for the support you've given me. That being said, the car is still not running.

The schematic you sent was very helpful, and I more clearly understand the function of the fuel system. I checked for a spark at each plug, and there is a good, strong, steady spark at each of them. Does this rule out the ignition system? I have fuel at the rail, and each of the injectors ohms out properly. The engine just cranks and cranks but will not fire. There are no codes stored. I'm getting toward my wits end, but because I'm a poor grad student I cannot afford to have it towed to a shop. I will continue to utilize the diagrams you sent, and any other advice you can offer would be a blessing.

Thanks for the patience.

kitch428 · Mar 8, 2009, 07:58 AM

It's important that NE (crank signal) is generated, then the ECM keeps COR on to keep the pump running.
If you have a bad pick up coil, then you'll need a new distributor.

Be sure the rotor button points exactly at #1 at TDC when you pull the cap. If not, your timing belt has slipped.

So, here's a page to start checking things out. An old test I like to start with is use an old plug, break the electrode off, hold the plug 1" away from jumping a spark to test strength.
But, sometimes a coil can ohm out good. Look for heat cracks on the coil where sparks can jump inside the cap. Try swapping distributors with a known good one if you can.

This should get you started. Be sure G and NE ohm out perfectly to specs.
ignition circuit.pdf