Engine Delayed Start - Toyota 1NZ-FE 1.5L

[SL Runner]

Hi Scott,

Yes, the technicians checked the fuel line pressure. They installed a pressure gauge in between the fuel line and the engine and they turned on the Fuel Pump using the terminal hooked to OBD2 port. As soon as we turned on the pump, pressure increased to 3.3. then after 5 minutes it came down to 2.8. And then we waited for 1 hour and it was 2.2. Is it normal? Technicians said it is normal. But before I change the pressure regulator, pressure drastically dropped to 1.0. Thats why they suggested to replace the fuel pressure regulator. Please advise.

[CTScott]

Originally Posted by SL Runner

Hi Scott,

Yes, the technicians checked the fuel line pressure. They installed a pressure gauge in between the fuel line and the engine and they turned on the Fuel Pump using the terminal hooked to OBD2 port. As soon as we turned on the pump, pressure increased to 3.3. then after 5 minutes it came down to 2.8. And then we waited for 1 hour and it was 2.2. Is it normal? Technicians said it is normal. But before I change the pressure regulator, pressure drastically dropped to 1.0. Thats why they suggested to replace the fuel pressure regulator. Please advise.

According to the service manual, it should stay at or above 1.5 kg cm2 when measured 5 minutes after turning the engine off. So if you are staying at 2.2 and hour later, then it is within spec. At an hour after turning off the engine, does it start fine? If so, how many hours does it seem to need to sit before you have the starting trouble?

[SL Runner]

Well..the issue is, when you try to turn on the engine after 5 minutes of turning off the engine - it struggles to start. I wish if can show you all this. :P . Just curious to know..Is there any non-return fuel valve available in the fuel pump? Is it exists, maybe fuel is leaking from there..But I'm worried as I witnessed the fuel line pressure back at the garage and it looked fine. Yesterday I drove the vehicle for 100Km and didnt experience any unusual issues. It has done 14Km/L. I wish if I have a tool to observe the fuel line pressure back at home. My gut feeling is fuel line pressure is dropping due to some reason...

[CTScott]

Originally Posted by SL Runner

Well..the issue is, when you try to turn on the engine after 5 minutes of turning off the engine - it struggles to start. I wish if can show you all this. :P . Just curious to know..Is there any non-return fuel valve available in the fuel pump? Is it exists, maybe fuel is leaking from there..But I'm worried as I witnessed the fuel line pressure back at the garage and it looked fine. Yesterday I drove the vehicle for 100Km and didnt experience any unusual issues. It has done 14Km/L. I wish if I have a tool to observe the fuel line pressure back at home. My gut feeling is fuel line pressure is dropping due to some reason...

The check valve has to either be part of the fuel pressure regulator or part of the pump.