agillings

Yes right. But I think it might of been part of my orginal problem. I will do the WOT problem. Thanks

agillings

Did Pressure testing results below on a cold engine:

Normal start
Key on = 49psi than decreases to zero with in 10 sec (no pinch)
Start Eng = 39psi - rev eng psi went to 49 psi (eng started right up)maintained 39psi at idle

Feed line test
Key on then pinched feed line 39psi
Key off went to zero within 10sec (pinched feed)
Release pinch on feed line
Started eng 39psi with eng running

RTN testing
Key on pinch rtn 60psi
Key off 60psi
Start eng 70psi
Key off eng stopped
Released pinch psi to zero.

Checked oil no gas detected

Does the above readings point to a bad FPR?

aklim

So you crimped off the feed line after achieving the right pressure and the fuel leaked out. Your crimped off the return line after achieving the right pressure and it held. Released return line crimp and the pressure fell.

This makes me think the leak is between the pressure line coming out of the pump and return line crimp. Could be the injectors or FPR spring is weak. Can't be leaking out so it has to be leaking into the engine or back into the tank

agillings

Thanks for quick response. There is no gas in the oil so I think the amount of pressure going to zero under the tests must be related to the Tank assy. The engine seems it is not running rich.

So correct me if I am wrong . I should pull the tank unit and check connections.
I have a new FPR if connections are good I should change the FPR Diaphram?

The eng starts right up after the testing. If fuel injectors were leaking, would it be hard to start?

aklim

How did you check the engine for rich running? You'd have to datalog it. I had injectors on the driver side short out so the O2 sensor thought it was lean, dumped a bunch of fuel on the other side. The manifold was glowing on one side, cold on the other. Datalog found an incredible amount of pulse width. Also you have a catalytic converter or 3 so that can compensate for it.

No. After the regulator, it is free flowing into the tank so it is between the crimps that you are leaking. You said you changed injectors. Which ones? All of them and recently? Cold start injector wasn't changed. Was the fuel pressure regulator changed as well?

agillings

The eng runs, no black smoke ,no black residue on tail pipes. No rich smelling exhaust. Starts up 2 or three turns

The injectors are about a 2 years old. All new Bosch (orange color).Cold Start injector was not changed.

Fuel Pressure Reg was rebuilt at the same time

So you are saying that I have a leak internal to the tank or the FPR or the injectors leaking

aklim

OK. Feel free to correct anything I said. I may have spaced out. Blame it on the booze. So let's work this out. It goes from the pump to the filter to the injectors to the regulator and back to the tank. The regulator holds pressure until it gets past a certain pressure and bleeds it off to the tank till it gets the correct pressure. Bleed process repeats.

You did a feed line test by crimping it after a second of prime to achieve full pressure so there would be no way the fuel can flow back. Any rapid loss of pressure is from that crimp on. That means it achieves the correct pressure and you do not allow it to flow back. So only way it goes is from that point to the regulator to the tank.

Can you repeat the return line test and not start the car so we can see if it holds pressure? You started the car so the motor bleeds off the pressure and muddies the waters, so to speak.

We know that from the feed line crimp to the return line, it doesn't hold pressure. If the return line test holds pressure, probably the regulator.

agillings

Ok Thanks. I will do the rtn line test in the morning thanks for you help!

agillings

Redone RTN Pressure test results below:

Key on/eng off no pinch reading 40psi. When it reached 40 psi went to 0 psi.

Key on/eng off Pinched RTN Line reading 40psi. When it reached 40 psi went to 0 psi.


So it looks like injectors or cold start injector leaking according to the Maintenance Manual flow chart

aklim

Looking like it. Just for the sake of it, try this. Crimp off the return line, pressurize it and then crimp off the feed line. If you do this ,it should hold pressure since the system is under pressure and it cannot return to the tank via the feed or return line. If it bleeds down, it will to the injectors or the cold start injector

agillings

I am leaning more towards a leaking Cold Start injector. I just got back from a test ride. The following occurred:

1. Eng started right up after all testing 2 to 3 cranks
2. Idled around at 20 miles per hour FP =39 psi
3. Went on highway 40 mph =FP at 39
4. WOT about 70 mph = FP=49. stablized at 39psi when reached 70mph. I will do the additional test in a few min. Be right back

aklim

Makes me think that the pump is doing the job. If you take the intake off, I suggest sending the injectors for testing at FIC. All 9 of them and ask him for a new fuel pressure regulator.

VikingTrad3r

aklim

I don't know if this is right but from what I heard, nobody sells it so you have to get used. I'd send all 9 for cleaning testing. Jon probably has a few good cold start injectors lying around if this one is FUBAR. I'm sure he has the gaskets on hand

agillings

1. Ok tested, RTN Crimped and Feed crimped after Pressure reached 39psi.
   
2. Result: PSI gauge went to 10psi and after 2 min then to zero.
   
3. Earlier when I to the C4 for a drive it ran great, 600 to 650 Rpm pressure steady at 39. Floored it, eng smooth, no misses, no hesitation pushed me back in my seat

agillings

FIC is were I purchased the injectors. Yes the plan is to take Plemmn off and test injectors. Or just buy new ones

VikingTrad3r

agillings

Thanks That is the
plan

aklim

Sounds like a injector leaking at least. Send all 9 for testing just to make sure

https://fuelinjectorconnection.com/collections/gm-car-rebuilt-injectors/products/24-lb-design-3-injector-set

https://fuelinjectorconnection.com/collections/injector-restoration-service/products/cold-start-injector-service-1

Check with Jon about which one you need He is honest so he will get you the right sized ones and have a look at the cold start injector and see how best to proceed with the order .

agillings

I am thinking of one additional test!

Remove the plenem . Delete the Cold start injector with a kit I have ordered.
With the Cold start injector disabled and it Pressure decreases to zero I will know it is the cold start is ok