https://youtu.be/wmJ_KwS5ohc
//youtu.be/wmJ_KwS5ohc
1994 Toyota Truck left me on the side of the road again. At anything over 800-900 RPM. Precisely timed on-off-on-off. Sounded so much like a faulty rev limiter that I changed out the distributor. Is it the Fuel pump again ?

 

I wish mine did that! I'd check all the regulars -- fuel pressure while running (luckily it runs) would be the start, then go from there. Keep in mind that fuel pressure within spec on the cold start banjo doesn't mean your fuel system is all good, it's just a good sign. If that seems fine then I'd try to spray some starter fluid into the brake booster port on the intake -- if it stays running with starter fluid, it's a fuel problem. If it doesn't, it's an electrical or air problem. That's the easiest place to start in my opinion. Autozone's "OEM Fuel Pressure Tester" rental includes the correct banjo adapter for our trucks if you don't own one (just be careful not to over tighten, it's very flimsy brass that WILL break).

 

Not letting me type an answer - It was the TPS coming loose

 

Does it only pulsate if the RPM is above idle, say much above 1000 RPM, and the brakes are applied?
If so, it's functioning correctly. There's a circuit built into the ECU that cuts the injectors if the RPM are anywhere above idle, and the brakes are applied. Toyota figured that if you had the brake pedal pressed, but the engine was above idle, they'd save a little fuel by shutting the injectors off until the RPM are down to idle, then allow them to function again.
So, if the idle RPM is set too high, when you step on the brakes, the ECU will shut the injectors off, the RPM will drop, the ECU will allow them to function, the RPM will climb back up, the ECU will shut them off, and so on. Easiest thing to do, is make sure the idle RPM is below 1000. IIRC, 850 is the correct idle setting.

Also, bear in mind that it's not just fuel PRESSURE that matters, but the flow RATE, the VOLUME of the fuel flow, matters just as much. It can be checked at the return hose of the pressure regulator. I believe it requires 0.5 liters per minute, minimum. I'm not certain about that, though. Pull the return line off the regulator, put a clear hose on it going to a graduated container, and use the jumper and key switch to turn the pump on. Time the run for 30 seconds, or one minute, and see how much has flowed into the container.
If the volume is low, it could be the pump, or the filter. The 22RE filter is large, but actually pretty effective. Problem is, it's so effective, that it can get clogged up if there's enough crud flowing into the system from the fuel tank. The "sock" on the fuel pump can get clogged up too, if there's crud floating around in the tank.
The Pulsation Damper, at the entrance to the fuel rail, can get clogged up as well. If the pump and filter are good, that might be something to check.

Also, the injectors might be dirty/partly clogged. The FSM has a good procedure for checking them. If the are clogged, you can get them cleaned/remanned for a reasonable price. I don't recall the names of any good shops that do injectors right off the top of my head, but I'm sure one of the super pros on the forum can chime in on that.

Finally, make sure the vacuum line to the pressure regulator is going to the right places at both ends. It should go to one of the VSV's mounted on the top of the valve cover. You can see it clearly on the vacuum diagram on the inside of the hood.
Make sure the VSV is functional as well.

Good luck!
Pat☺

 

The TPS had come unscrewed - You can see it doing monkey motion if you look closely.
Carb cleaner into the manifold did not diagnose this.
It ran continuous and gave a false answer to fuel pump fault test