Intermittent LT1 Ticking?

[97Formula]

Originally Posted by sweetbmxrider

Actually, your previous fuel pressures were correct. 55-60 is too high. GM specs 40-49 I believe Key On Engine Off and 10 psi less engine running. There is no fuel pressure sensor so the engine wouldn't throw a code for that ever.

I wasn't expecting fuel pressure to throw a code.....was thinking that I should've had at least a trouble code or SES light for a LEAN fuel mixture, or a misfire, or something...

This was a GM dealer telling me where the specs should be for this car. Is there an issue with the fuel pressure being that high? And how would "the customer" (me) challenge the dealer mechanics what the correct fuel pressure should be? The engine runs better now than before the pump replacement (they also "power-cleaned" the injectors).

One other thing I noticed (after the fuel pump replacement).....after filling the tank, the gauge was between 3/4 and F (instead of 2mm beyond F). Took it back, they dropped the tank once again to test the sending unit (I am under the impression that GM sells the fuel pump kit with a new sending unit installed). They told me the new sending unit is at the correct spec (90-OHM), and my old sending unit was too high (103-OHM). They tried another fuel pump assembly unit with the same result, same reading, etc. Then they told me they manually tweaked the float arm (not sure how this is done, and they told me they did not bend it). It's a little closer to F but not quite there yet (not sure if this is because they did not put all the gas back in the tank when they lowered it a second time).

[sweetbmxrider]

Its a pretty known issue that these sending units were off from the factory. If your gauge is closer to F, you should brag about it at car shows

Ask them to show you in the service manual where it specifies the pressure they told you?

FUEL SYSTEM PRESSURE
Ignition ON Engine OFF 284-325 kPa (41-47 psi)
With Regulator Vacuum Applied [1] 3.0 - 10.0 psi less than Ignition ON Engine OFF

REMARKS:
[1] May be checked with either of the following methods.

With Pressure Regulator Vacuum Line Attached at normal idle speed.
Ignition ON Engine OFF with 10 Inches Of Vacuum Applied To The Pressure Regulator.

This is how AllData lists a 95's fuel pressure. They Only listed Key On pressure for 97.

There's a chance that cleaning the injectors helped the car out. If the extra fuel pressure is band aiding a problem, well you have to figure out what it is. The SES light will trigger for lean too only if the computer can no longer compensate for it. There is a chance that your Fuel Pressure Regulator is bad causing your higher pressure.

[97Formula]

Went back to the dealer, and turns out they did wind up referring to the 1998 shop manual for the fuel pressure . However, they ordered the parts based on the VIN number (so I should assume I have the fuel pump for my 1997 model).

I guess I will need to confirm the actual pressure on my own. Car still runs more awesome now than before the repairs. My only concern now is the fuel gauge.....


BTW -- I know the original thread was regarding ticking sounds (which I did ask the dealer to check while in the shop......they indicated on the bill "no unusual noises heard"). Car also doesn't sound as "stressed out" when I punch it and going towards the upper RPM range (instead it seems more willing at that range now).

One last thing -- before the repairs I noticed less "hissing" noises by the CAI filter (actually it was kinda intermittent, wondering if that was due to lack of fuel and the computer was constantly adjusting the fuel mixture to keep it going). Now, there is a "steady" hiss that is most noticeable at startup (which is how it should be)...