Hi have a 1988 camy 2litre i just recenty got from a friend. He gave it to me for a hundred dollers and he said he thinks it needed a fuel pump. So of-course i was eager to get it running and jumped right into taking the tank off(i didn't make waste time making sure the pump was functional before i took off the tank) to change the fuel pump when i got the fuel pump out i tested it just to make sure it was bad and sure enough it was good. So now i have a tank to put back on and wasted about 2 hours of time taking it off its going to be a **** trying to get it back in. So anyways i have no idea what to do from here. The symptoms are the pump not turning on when i turn the key. I override the relays using the diagnostic box and my friend told me he put some new relays in it anyways. The only thing i can think it would be is something wrong with the ecm or mayby a cut wire. I did notice some frayed wires on the fuel pressure regulator, could that be the cause of it not turning on. Also could i somehow hard wire the pump by switch or would that make the pump overwork itself. I tried to trace the wire from the fuel pump but was unable to recognize the fuel pump wires when i got under the dash. So what do you guys think. thx jake

 

It appears the pump will only run when the ign switch is turned to start or the engine is running.

The relay controlling fuel pump operation appears located behind the lower center console of the dash, near engine computer. It's called a Circuit Opening Relay (COR). May be mounted on the firewall?

This relay has two solenoids (instead of the typical one) that control the actual switch operation inside the relay. This switch turns on power to the pump.

This switch inside the COR relay that turns on the fuel pump receives power from the EFI relay (might be a Red/White wire) via the EFI fuse through the switch to the pump (might be Blue, this wire going to pump).

The EFI relay and fuse should be in a fuse/relay box in the engine compartment.

This EFI power also connects to one of the solenoids (call this solenoid A) of the COR. However since the other electrical terminal of this solenoid is not grounded at this time this solenoid does not turn on.

When the ign switch is turned to start, power runs for the ign switch to the 2nd solenoid of the COR (call this solenoid B, Black/White wire), through this solenoid and to ground (White/Black). When this solenoid is powered the COR switch is closed and power runs to the pump run to turn it on.

Once the engine is running, a switch inside the MAF sensor closes. The sensor contains a vane which moves with intake airflow to close a switch.

This switch is wired into the ground wire for solenoid A of the COR (Green). When the MAF switch closes, the circuit for solenoid A is complete (remember it had power but was not grounded) and it turns on keeping the COR fuel pump switch closed and the fuel pump running.

Might help to make a drawing.

 

I must have confused you the fuel pump only works when directly connected to power like on a separate power source the fuel pump does not work when it is plugged into the car(no matter what position the key is in) So far i have not even heard the car run. So is it possibly the (cor) relay. Also would it override all relays when i connected b+ to fp in the diagnostic box because i did that and got no result.

 

The pump should run when the B+ and FP terminals are connected AND the ign switch is on. If it does not run, there is problem. This method overrides the COR relay but not the EFI relay which powers the pump.

When this method is used, power comes from the EFI relay (same as when pump is operating normally) but bypasses the COR via the jumper cable then through the Blue wire (via a few wiring connection points) to the pump.

With ign switch on, check for 12V DC between the B+ terminal and ground with ign switch on. If power is here, the EFI relay is OK and the fuse that powers it. If no power there is problem with these items or further up the power stream.

If power at the B+ terminal the problem is wiring between the COR and the fuel pump.

Check the ground wire for the fuel pump, White/Black.

You can apply power directly to the pump via the Blue (+) and White/Black (-) wires.

The fuel pressure regulator is mechanical, no wire.

Take note, the fuel pump area also has the fuel tank sender for the gas gauge. You don't want to apply power to the sender whose wires might be Yellow/Red, Yellow/Blue, Brown and White/Black (ground-might be same ground as for fuel pump).

There might be a fuel pump access by taking out the lower rear seat cushion. Once the lower seat is out, there might be a cover plate. Remove the plate and this will expose the upper part of the tank allowing access to the fuel pump area. If this is the case, the pump can be removed without dropping the tank.

Or if the tank is off, look up under the car chassis at where the fuel pump would be when installed for a oval hole covered by a plate.

 

Can i just run my pump directly off the battery and a switch, and how does the regulator work does it just make the pump run all the time and when it gets to pressure it bleeds gas back to the tank. Thanks for your help you been giving me some good info.

 

You can connect the pump to the battery via a switch. The COR switch is there to prevent the fuel pump from running when the engine is off as in the case of an accident.

If going this route suggest at least wire the pump to a circuit that only powers on when the ign switch is on.

The link below has info on an inertia switch that will cut off power if the car is hit in an accident.

http://www.smartracingproducts.com/p...00_fuelshutoff.

The pump runs when the engine is on.

The fuel runs to the engines fuel injector rail under pressure from the pump, excess full is routed back to the fuel tank by another line.

The pressure regulator is installed on the fuel rail before the fuel return line. The regulator has a diaphragm installed in an airtight can. One side is connected a valve controlling the amount of fuel routed back to the tank the other to a vacuum hose going to the intake manifold.

For fuel injected engines it is ideal to control the fuel pressure to within a narrow range (say 37-42 psi) to obtain a decent injector spray pattern and quantity of fuel injected within the pulse range given. The injectors pulse to inject fuel, the amount of fuel injected is control by pulse duration.

Without a fuel pressure regulator, fuel pressure would fall as the engine used more fuel when driving at say 60 mph and rise when the car is stopped and engine at idle RPM.

When the engine load changes (driving versus idling) the manifold pressure will also change in response to the load. The diagram controlled to manifold pressure will move in response to this and if connected to a valve, the valve will also move (open or close).

This system effectively controls fuel line pressure to within a narrow range.

 

ok so i wired up the fuel pump and i have fuel pressure now there is fuel getting to the engine but i have a new problem. There is no spark, so i am guessing that the reason why there is no spark is the same reason there was no fuel(fuse or realay) so i got a haynes manual and i was looking at some diagrams of the fuel pump schematics and the ignition schematics and the olny thing i see in common is the ign and the ecm. Also the thing that is on the air intake I am guessing it is the maf its the thing that has a the little flap that opens and closes. The flap is not opening. I have it pluged in though. So what do you think.

 

Send a private message with email address and will send a file on troubleshooting this ign system.

The pump should still work when the ign key is turned to start. The vane switch takes over when the engine is running and pulling in air.

 

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Hello brotherhood,

¤As it is, my car does not start due to not having fuel delivery during cranking * I have jumped the fuel system, it all functions (*including opening the AFM door) * The COR solenoid relay interests me greatly, and try as I might - especially after Mr. Yomoha's kind commentary about where to find it - I tried to locate it with no luck - all I have found are some A/C controls & seatbelt relay & such - nothing like the part that I've seen in Rock Auto Parts * please help, thanks¤

 

¤Sorry, correction, in due respect.. , my blog should read '...after Mr.Toyomoho's kind commentary...' * Once again any and all recommendations as to where to find the elusive COR relay - will be hugely appreciated, danke ¤