My 3rz swap is functioning on 18 psi fuel rail pressure according to the lce gauge. It used to run/start fine however its having some hard starting issues now after it sat for a few months in my shop after changing the transmission.

It will crank forever with no dice until I shoot some acetone/cleaner on the air filter and it starts up.

Ive taken apart the throttle body and am cleaning the iac valve. The intake is gross inside lots of black carbon and soot. The fuel pressure regulator is plumbed to return to the tank. If i plug the return the rail pressure only rises slightly ~20psi

so either
1 my iac valve is messed up
2 the fuel gauge pressure is incorrect
3 the fuel pump is not making pressure
4 the fpr is also messed up

Im new to these engines and the swap was done by the previous owner is there any reason why someone would run the engine at low fuel rail pressure?

 

I can't think of any GOOD reason someone would do that. Maybe they had a leaky crush washer someplace and lowered the pressure somehow to make it stop. I'm not sure HOW they would do that, though.

Sounds to me, for what it's worth, that either the fuel pump is getting old, and not putting out the pressure it should, or the system is clogged up with gunk. The "sock" on the fuel pump, the fuel filter, the lines, etc.
The pressure regulator is plumbed correctly, BTW.
To me, I would check the pressure at the fuel filter inlet. That will tell the tale. If it's still low there, fuel pump is going bad. If it's good there, filter is probably getting clogged up. If the filter is full of gunk, though, where did it come from? Bad, dirty fuel, rust flaking off in the tank, something.

Does this help at all?
Pat☺

 

yeah thats a good plan. Im wondering how its running at 18 psi. I just wanted to make sure I’m not unfixing a mod or something

 

Poorly, at best, I wager

I don't THINK so, for whatever that's worth. Not unless the PO put in an aftermarket, adjustable, fuel pressure regulator someplace. You would be able to see something like that pretty obviously, I would think. I can't imagine WHY someone would want to do that but hey, whadda I know?

I don't think your oem pressure regulator has gone bad on you, but it might have. Pull the vacuum line off the fuel pressure regulator, plug the vacuum line so it's not leaking vacuum, start the engine, and see what the pressure is in the system. According to the FSM, it should be 38-44 PSI. If it's low, as you've been describing, try all the stuff I said last post before. If it's normal, reconnect the vacuum line, and see what it does. It should drop to 33-38 PSI, at idle. If it drops to the 18 PSI you're describing, it may well be the pressure regulator. Only way I know of for sure to verify it, is to replace it. See if you can isolate the problem before you throw parts at it, though.
Make sure the vacuum line isn't leaking! Not expensive, and easy to replace if you have ANY doubt about it. Can't hurt to replace it if you have any doubt about it.

Remember, you can never reuse crush washers. Always replace with new if you undo one for any reason. Any crush washer you remove, even if you just screwed down onto it briefly and lightly. It's a good idea to have several washers on hand, for any join you might take apart during all this. You never know.

A last note: Be wary! If you are about to install the last washer you have for a particular join, it will try to leap out of your hand. It will then jump around until it falls out the bottom of the truck, and vanish. It can fall onto a clean, dry, level, bit of concrete, and it will STILL manage to vanish. They are malicious that way, they really are. That's why it's a real good idea to have extras. It tricks the little devils so they don't try to get away so hard.
REALLY!

Have fun!
Pat☺

 

I really appreciate the input. Yeah its funny it ran great all last summer went offroading a few times. Drove around alot haha. Guess its just a toyota so its hard to kill 😬😬

 

Ok so I replaced the fpr the regulator was working fine it seems and my gauge was wrong. The fuel system is working.

The engine makes a weird high frequency buzz when running now i cant tell whats causing it. The engine starts fine if I shoot some cleaner down the intake, but it dies if you crack the throttle. If I slowly open the throttle and coax it into increasing rpm it responds fine.

mystery continues anyone have ideas?

 

Fixed the issue by replacing the engine coolant temp sensor on the back of the block. Pain in the buttstuff to get too but now starts first crank and runs perfectly