I have a 2000 Mazda B3000.
That is the 3.0L Flex Fuel, but I am running Gasoline.
It sat for a few years and I have been through all of the issues except one. It has new plugs and wires, Air Filter, Injectors, O2 Sensors, Fuel Cap, Radiator Cap, DPFE, EGR Solenoid Valve, and EGR Valve. I have also cleaned the MAF and intake.
The previous owner claims he had changed the fuel pump, but I am not certain of him being trustworthy.
After all of this it runs fantastic.

I have one problem left. It will not start at times without holding the gas pedal down. It turns over for quite a few seconds. Sometimes I can just give it a little bit of air by pushing down the gas pedal and others I will pump it a couple of times and then hold the pedal down.

I replaced the IAC and crankshaft sensor to fix this problem, but it still happens.
I tested the Throttle Position Sensor and it appears to be good.

Bought a fuel pressure gauge.
KOEO the gauge goes to 50 psi and will hold for many minutes.

Start the truck and it goes to 59 psi and stays there no matter what the rpm.

Turn truck off and gauge drops to 53 psi and will hold for many minutes.

I did this many times with the exact same results. Truck always starting without hitting the pedal.

I then ran many tests by releasing the pressure and then going to KOEO and I got consistent 50 psi and holds.
Out of all of these samples the truck did not start without pushing the pedal one time. I turned it over for a few seconds and it did not start so I went to view the gauge before I hit the pedal and it was still at 50 psi. I then held the pedal to the floor and it started. Gauge went to 59psi.

I have read fuel pressure should be about 55-65 psi at all times.

Am I on the low side here only having only 50 psi at KOEO or are my results fine?

Any other suggestions to fix this issue?

I have now seen that Flex Fuel trucks operates at a lower fuel pressure than gasoline and my numbers are not low.

Is it normal for the pressure that I have at 53 psi in Key On Engine Off is lower then when the truck is running with a pressure of 59 psi or should the fuel pressure be the same in both situations?

It is fuel injected. You are not supposed to press the gas pedal when starting. Turn the key on, wait a sec, crank.

Yes. I am aware. That is the problem.

wth ???

Did you read my post?

It clearly states that it will not start without pressing the pedal.
That is the problem.
I am well aware that it is fuel injected and that I should not have to push the pedal.

OK. So it does start when you press the gas pedal ?

See what happens when you turn the key on and off a few times. Has the fuel filter ever been changed?

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2014 F150 xl 3.7 6 speed auto.

Yes. It does start when I hold the pedal down.

It starts about half of the time when I do not push the pedal down.

I did change the fuel filter. I forgot to add that to my post.

I did try to turn ignition on and off a few times when the pressure gauge was connected. Pressure will not rise above 50 psi unless I start it or 53 psi if it was previously running.

Consistent 59 psi every time I start it.

No vacuum leaks ? Never know with these picky Vulcans.

When I first replaced the idle air control valve with an aftermarket unit I thought the problem was solved because it did not act up for a few days.
Maybe it was and I got a bad part.
I just ordered another idle air control so hopefully that will solve it.

Problem fixed.
It had three leaking exhaust valves. Two dropped compression 20% and the worse one was down to 90 pounds compression on cylinder number two. I was also getting a bit of a rough idle at times. Surprised how well it ran with those issues.
Installed two rebuilt heads today and it now runs and starts excellent.

Good! To bad it was pretty major but glad you got it fixed.

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2014 F150 xl 3.7 6 speed auto.

Thank you!