1st gen fuel delivery issues

My 95.5 V6 is having an odd symptom. After driving, if we try to start it up 5-60 minutes or so after shutting it off, it fires off for a second or two and shuts off. I have tried a few things and now realize it has to be fuel pump/delivery is not happening. Today I shot a small amount of starter fluid in past the filter location and it ran for 5 seconds very smooth and shut off. After the second time of this (and installed the filter back), it continued to run just fine. I feel comfortable to eliminate injector leakage and flooding.

This leads me to the fuel pump, the EFI relay or the green relay under the dash known as the "circuit opening relay". I found that relay a few moments ago. I am considering attempting to bypass that relay. Has anyone had an issue with this device similar to what I am seeing?

I understand 1st gen tacos do not have a resistor for a 2 speed fuel pump operation. What is the purpose of this circuit opening relay? Is it for detecting oil pressure to continue fuel delivery? I would have thought that would be through the ECU and signal control to the EFI relay.


Thanks in advance for your inputs,
Mike

 

From your description of symptoms it sounds like either the check valve in the fuel pump is bad or the fuel pressure regulator is bad and is not holding fuel pressure with the engine off which is allowing the fuel to drain out of the lines causing a long crank.

You would need to tee a fuel pressure gauge inline to confirm this.

 

I could see the check valve in the pump.

pressure regulator I sort of rule out as if I cycle the key 10 times to pressurize the system, it still won’t start and run.

It literally runs for a second or two anytime at initial cranking. It just doesn’t stay running. I have been reading on the COR, and find likely cause to be there. I am not wanting to buy an $85 relay that doesn’t fix it.

I am still listening to you and others about this. Please understand I am not discarding your suggestions. I don’t want to drop the tank yet either. I do have a new Denso pump if really needed.

Mike

 

Toyota does not use a key on prime like many other manufacturers, the pump only runs during cranking and after the engine has started so cycling the key will have no effect.
The best way to diagnose this would be to have a fuel pressure gauge hooked up to it and verify fuel pressure holds after the key is turned off.

 

I will look at what I need to do to see this.
Is there and easy way for me to connect a gauge? Any leads are appreciated.


Mike

 

I'm not sure where the best spot would be to tee in on a 1st gen, I'm thinking where the line from the engine connects to the line on the frame in the engine bay.

I think it's either a 5/16 or 3/8 flare fitting but I'm not 100% on that, I work on very few tacos and I own a 2nd gen which has quick connect fittings.

 

Well now… that’s not fair. lol

 

Srry lol.

Last one I had to hook a gauge up to was a 1st gen Tundra and it had flare fittings, I'm thinking 1st gen tacos would be similar being they were on basically the same platform.