3rz Fuel Pressure and Rough Starts (solved)

Is it normal for the fuel pressure win the fuel rail to bleed down after 30 minutes or so. I’m right under 50# when running. I’m having some rough start issues after installing a cold air intake, adjusting valve clearance, replacing plugs and wires, replacing IAC, replacing fuel filter and injectors.

 

@Taco critter

 

Was engine running rough, before all the new parts?

 

No, which makes me think it is a part or something I did; I like your picture I for the first after owning my truck for 20 years saw the 3rz stamped on the block yesterday.

 

Most of the fuel rails I worked on, after time,
do lose pressure after time.

Run a cylinder compression test, check those cylinder compression numbers.

Any engine codes?

 

What injectors did you put in, and where did they come from? There's a rash of bogus ones out there.

 

GB remanufactured. Maybe one is leaking?

 

No codes. Engine compression test was good.

 

Hmm. I just tried searching for the thread on this. Maybe @CS_AR will chime in, he's done quite a bit of good research on the topic.

 

If I let it sit for two days or ten minutes it starts good otherwise pretty rough.

 

This is definitely the case; if it sits for 10 minutes or a day it starts terrible but if it sits a few minutes or two days it starts like a champ.

 

How could I test for a leaky injector? Will I find gas in the cylinder after I turn it off? Will the gas be on the valve seat if it is closed? If that is the case I will need to rotate the crank?

 

Well no luck discovering anything with this test; I’m running out of ideas.

 

https://community.cartalk.com/t/possible-vapor-lock-problem/53280


It kinda sounds like vapor lock, but that isn't something I usually associate with fuel injection.

 

For checking fuel injectors: Check out this video on DIY fuel injector test will need some of the testing tools.
and this video for checking leaking fuel pressure.

What were compression numbers (were those equal)

It could be a defective new or remanufacture part was installed, or new engine issue.
Rechecking new installed parts, o-rings, and other parts might be helpful.
With no engine code, this make trouble shooting the engine problem more difficult.

If you have Factory Service Manual for your year, make and model, and engine size, there are trouble shooting diagnostics that can be done on the parts installed and other engine parts.

 

In that video I question how the injectors stay in the fuel rail when taken off the head?
I forgot if we decided it was normal for the pressure to bleed off slowly?

I’m thinking of doing an oil change to see if any gas is in the oil.

I bought one more injector; I’m thinking I will run the truck for few minutes then shut it off then pull the injectors and hopefully I can see the fuel that has leaked by.

 

Well I think I found the bad injector, one of the four sent by rock auto had a different color than stock and the other three they sent me.

I hoped to be able to see the fuel on the valve or in the cylinder; I could see neither. I couldn’t hear any difference in the injectors either with a stethoscope. Only difference was the design of the ports where the fuel comes out so I chose to replace that one and so far so good.

by the way my fuel pressure is holding at 45# now with the car off.

pics below of the black sheep injector.

 

Well starts are still good but the fuel pressure does bleed down after an hour or so.

 

Well it’s official it was the bogus injector that they sent me that was causing the rough starts.

 

right on good read. i;m currently experiencing this issue on my 3rz except not having a significant rough start, partly due to the fact that i had a really bad rough start issue but a new IAC valve fixed that and i may not be noticing a slight rough start now. but now i still have gas in my oil based on the white towel test and a slight hesitation when i start the truck within an hour or so but not all the time.