Reuben1

I have a 1992 Toyota Pickup with a 22RE engine and the truck would not start when warmed-up. I have read many threads regarding this issue but nothing worked. After much frustrations, just by chance, I noticed that the battery was 8 years old. I replaced the battery and it made all the difference. The truck not only started with gusto every time, the truck ran a lot better. If you every encounter this problem with your truck, and it runs fine except for warm start-ups, try replacing your battery. I hope this helps.

Schrade

You might want to check your static fuel pressure, AND pressure leakdown time.

If you have leaking injectors, or a ruptured FPR bladder (which will allow fuel into the vac supply line), you'll get more fuel in the cylinders than is needed. Fine for COLD starts, but HOT restarts will be hard.

RAD4Runner

Define "Start"

Crank as in starter turning the engine?
Combustion as in VROOM?

Reuben1

Start: engine turns over (cranks) normally but the engine does not run by itself. Warmed-up: normal operating temperature.

scope103

If the FPR regulator diaphragm ruptured, wouldn't you be pumping fuel directly into the intake manifold whenever the pump was on? While the pressure to the injectors would be too low, fuel pumped directly into the manifold should flood out the engine, hot or cold. (Could you be thinking of a leaking vacuum line to the FPR? That would result in higher rail pressure, more fuel, run rich.)

Actually, adding more fuel pressure for HOT starts is exactly what the FPU (Fuel pressure-up) system does. It's purpose is to address vapor lock.

Schrade

Correct scope - it WOULD increase fuel pressure, but it would leak more fuel into the FPR vac hose and into the manifold FIRST, not the rail.

But this would be in fuel injected system, not carb'ed. I had that part wrong...

I don't THINK this is correct scope - at least not on FI systems. I gotta' see that in the Toy. Shop Manual. Hot starts require LESS fuel. ECM on the vehicle would be getting a temp reading from CTS, if equipped, and REDUCE injector pulsewidth. Again, this would be FI systems.

I bet carb'ed systems have a similar function.............................

scope103

ALL answers are found in The Good Book. http://personal.utulsa.edu/~nathan-b...82operatio.pdf "When the engine is hot, the fuel pressure is increased to control percolation in the fuel system and improve restartability and idling stability."

What did you think was the purpose of the FPU? http://personal.utulsa.edu/~nathan-b...ne/99fuelp.pdf

I don't make this stuff up.