Fuel Pressure Test 1998 5.7

I tested my fuel pressure today and was wondering is this is correct. Keep in mind this is a new engine with the upgraded injectors. Fuel Pump is an 8 month old Delphi.

Initial turn on gauge goes to 62 psi then when the pump shuts off the needle goes to 60 psi and holds.

When I start the engine the needle "vibrates" between 52 PSI and 62 psi.

When I shut of the engine the needle goes back up to 62 psi while the pump is still running then settles down at 52 psi.

Are these numbers correct?

I tested my fuel pressure today and was wondering is this is correct. Keep in mind this is a new engine with the upgraded injectors. Fuel Pump is an 8 month old Delphi.

Initial turn on gauge goes to 62 psi then when the pump shuts off the needle goes to 60 psi and holds.

When I start the engine the needle "vibrates" between 52 PSI and 62 psi.

When I shut of the engine the needle goes back up to 62 psi while the pump is still running then settles down at 52 psi.

Are these numbers correct?

I don't see anything wrong..how does it run with this work completed.......

It runs like a champ. I just thought the needle was supposed to stay stationary while the engine was running.

What made me check it is that I can hear the fuel rushing through the return line, something I never heard before, and I am getting P0420 and P0430 Cat Codes when I come to a stop and idle after driving for awhile on the highway. Wanting to eliminate all other posibilities before I buy new cats.

It runs like a champ. I just thought the needle was supposed to stay stationary while the engine was running.

What made me check it is that I can hear the fuel rushing through the return line, something I never heard before, and I am getting P0420 and P0430 Cat Codes when I come to a stop and idle after driving for awhile on the highway. Wanting to eliminate all other posibilities before I buy new cats.


when the engine is running the injectors open /close this is causing the fuel pressure to rapidly pulse...normal..

with your codes the cat converter is reporting a condition to the PCM that pollutants are not being controlled...I would swap the O2 sensors to see if the codes change...If not then the cat converter is bad..

Didn't figure that the needle would keep up with the injectors but I see I does.

I don't think that swapping the O2 sensors will do any good since I am getting codes for both. Thanks :iceslolan

Didn't figure that the needle would keep up with the injectors but I see I does.

I don't think that swapping the O2 sensors will do any good since I am getting codes for both. Thanks :iceslolan

I'm sure you already checked for the exhaust having, no leaks, and the O2 wires/connectors are good...

I could not hear or feel any exhaust leaks but will get in and re-torque things this weekend. As for O2 wires, all are good and hooked up. Thing about the O2's, dealer had it the day before I got first codes and did an Exhaust
Pressure test that I believe involves removing the O2 Sensors. They pled not guilty of course. :sarcasmsign:

I could not hear or feel any exhaust leaks but will get in and re-torque things this weekend. As for O2 wires, all are good and hooked up. Thing about the O2's, dealer had it the day before I got first codes and did an Exhaust
Pressure test that I believe involves removing the O2 Sensors. They pled not guilty of course. :sarcasmsign:


because both dtc came on at the same time this is strange..I would try some emission cat converter cleaning additives to the fuel,,give it a few hundred miles to work...

new engines produce a lot of dirty exhaust when first running, this may be why the converters are not keeping up with the removal..the products used to help clean the converter with the cost of the converter is worth a try..

I look for Cat Cleaner this weekend. Could the dealer have damaged the O2 sensors they removed?

FIRST! Clear the codes and see if they come back.

FIRST! Clear the codes and see if they come back.

I guess I have cleared them a dozen or so times now. I was hoping that my long highway drive last weekend would clean things up but as soon as I came to a stop the light came back on.

I look for Cat Cleaner this weekend. Could the dealer have damaged the O2 sensors they removed?

It is possible that they put too much anti seize on the threads and messed up the sensor,,,sensor loose, wires /connectors not properly secured...I would remove and inspect the sensor see it it looks good..
make sure they installed the same correct sensors...

I have seen and also been a victim of dealer fraud...they will put older defective parts in to get more cash out of you...or just break the part...

this is my opinion ..my experience...

I have seen and also been a victim of dealer fraud...they will put older defective parts in to get more cash out of you...or just break the part...

this is my opinion ..my experience...

Funny you should bring that up. When I first started this motor up I had a dieing issue I could not figure out so I took it to the "stealer". They traced the problem to the ground on the front of the block. Then on their second test drive, the Crank Position sensor, which is right by the bolt that they tightened, mysteriously went bad. (This is when they did the exhaust test.) I cried foul and settled a $650 bill for $300. The Cat Codes showed up the very next day.

Funny you should bring that up. When I first started this motor up I had a dieing issue I could not figure out so I took it to the "stealer". They traced the problem to the ground on the front of the block. Then on their second test drive, the Crank Position sensor, which is right by the bolt that they tightened, mysteriously went bad. (This is when they did the exhaust test.) I cried foul and settled a $650 bill for $300. The Cat Codes showed up the very next day.

this is so common ...I hope you get all this resolved with no more dealer trouble...this is why I was against the GM bail out...why help crooks..gm buyer since 1967...

bad / loose grounds can very much damage the electrical system/computer...

No more trips to the dealer for me, that's why I am buying an Autoxray 6000.

Thanks.