My 94 toyota pickup runs great for around a minute then the fuel pressure dies off. Will restart and do the same thing. Put a new fuel pump and mounting bracket in and new strainer and filter. Any Ideas?!?!?

 

What does the fuel pressure drop off to? Does it depend on throttle (accelerator) position?

What part is the "strainer"?

 

Fuel pressure drops to zero over about 3 seconds. Its the strainer that goes on the bottom of the fuel pump. Another thing it was doing originally was when it was cold outside it wouldn't start at all, as soon as it started warming up outside it would start and run perfect and it gradually made it to this problem.

 

Turning the key to STArt runs the fuel pump, then the VAF/COR circuit keeps it running as long as the engine is sucking air. If there is a problem in the VAF/COR it will usually quit a little faster than "a minute," but it's easy to test.

Jumper FP to B+ in the diagnostic connector (this forces the fuel pump to run with just key-on). If that allows the engine to keep running, then your problem in the VAF/COR circuit.

(Don't drive around with the jumper. If you get in an accident that breaks a fuel line, you'll want that fuel pump to shut off immediately!)

 

I am not familiar with the 3.0 but that sounds like a symptom of a bad Cold Start Injector Timing Switch. A quick resistance check will tell you if it is bad. I have never had a Cold Start Injector to fail but the Timing Switch is more common on failing. I have had it to happen twice. Seems like the temperture was in the 50 degree mark and it would not start, when it warmed up later on during the day it would fire right up. The Timing Switch is what you will see missing out of the salvage yards. A high sought item around here.

 

Scope 103, I jumped those two terminals in the diagnostic box and it stayed running. By the VAF/COR circuit are you saying the mass air flow sensor? If so is there a way to test it so i don't have to waist $180.00? Appreciate the help!

 

It could be anything in the circuit

I would check the relay first

 

All answers are found in The Good Book. http://personal.utulsa.edu/~nathan-b...92volumeai.pdf

Now, I'm sure you're not going to make the following mistake:




wyoming9 is correct that it could be the relay, but the VAF ("Vane Air Flow Meter", a mass air flow meter is different technology) is much easier to get to and check with your multimeter.

 

I had this same problem with my 22re. After a lot of trial and error testing connections and swapping parts with a buddy I ran out of hope and Replaced fuel pump for the hell of it and It ran great after that. Have you pulled the fuel pump to check the strainer for rust or chemical buildup?

 

Not sure what other problems you are having but on my 92 4runner I had similar problems. Changed fuel filter, fuel cap, pre start injector and finally fuel pump. still had same symptoms. Finally changed the coolant temp. sensor and walla. Problem solved. I think this is overlooked a lot. It in directly involved with the circuit that starts and maintains the fuel pressure in the ECM. Hope this helps.