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  1. pkufeldt

    Valve Stem Seals Differences

    An update. Groveling through the service manual, I found the valve stem specs, looks like GM parts would need to stretch around the stem (0.3410 > 0.3270), but the FelPro would loosely fit onto the stem (0.3410 < 0.3440). Would the FelPro's even seal? And I see from the service manual there...
  2. pkufeldt

    Valve Stem Seals Differences

    Thanks for your recommendations, was worried there was some material/temperature differences between exhaust and intake. Didn't even notice the difference in seal type. Appreciate your pointers. However, looking around at the differences between positive and umbrella seals I am seeing a...
  3. pkufeldt

    Valve Stem Seals Differences

    So looking at replacing my valve stem seals and notice a couple big differences between FelPro (SS72861) and GM Genuine (10212810,12564852) seals. First is that the GM Genuine exhaust and intake are separate product numbers and look different, while the FelPro set supposedly has both but they...
  4. pkufeldt

    Instant 10psi drop in fuel pressure

    Just to wrap up this thread, thank you for your video showing that this fuel drop is probably OK, with just the check valves on either side of the fuel loop contributing a small drop (4-5psi each) while closing.
  5. pkufeldt

    Instant 10psi drop in fuel pressure

    No one seems to know what CMP Retard Alternate is. It is not listed in the service manual as a valid PID, but Car Gauge finds it during the scan.
  6. pkufeldt

    Instant 10psi drop in fuel pressure

    I will look into this. I got my CMP retard to 0 and it varies from 0.1 to -0.1°. You setting yours to 2 got me worried. Does this look OK? I don't know exactly what CMP Retard Alternate is, but I watch it anyways. Car Gauge Pro weirdness.
  7. pkufeldt

    Instant 10psi drop in fuel pressure

    How do you do that?
  8. pkufeldt

    Instant 10psi drop in fuel pressure

    Just saw your video, I guess I am chasing my tail with the fuel pressure.
  9. pkufeldt

    Instant 10psi drop in fuel pressure

    I was afraid of that. But the larger context is that the engine is misfiring (See https://www.gmt400.com/threads/misfires-return.62862/) and fuel pressure is an issue I can't seem to resolve. From the service manual: When it is idling I drop from 51-52 to 49-50psi - I assume that is due to...
  10. pkufeldt

    Instant 10psi drop in fuel pressure

    I replaced the fuel pump because of this issue and this drop remained unchanged from the original pump to the new pump. Even so, wouldn't a leaking check valve cause a continual drop in pressure? After this 10psi drop the pressure holds. There is very little from the fuel filter and the...
  11. pkufeldt

    Instant 10psi drop in fuel pressure

    BTW: The J 42873-1 shut off valve has schrader valves on both sides of the valve and I have measured the pressure on both sides. On supply side the pump is capable of 100+psi.
  12. pkufeldt

    Instant 10psi drop in fuel pressure

    Delphi FG0092 fuel pump. GP Sorenson 800-1513N spider.
  13. pkufeldt

    Instant 10psi drop in fuel pressure

    I have a 1999 K1500 Suburban with a 5.7l. It exhibits an instant 10psi drop in fuel pressure when the fuel pump stops while doing a key on engine off test. It goes from 61-62psi (in spec) while the pump is running to 51-52psi (out of spec) when it is off. It holds there. I have followed the...
  14. pkufeldt

    Misfires return

    So I am still struggling with the misfire problem. Since the last message I have replaced all of the O2 sensors, buttoned up the intake leaks and FTs have lowered. I also replaced the fuel pump. I still have the same fuel pressure issue, fuel pump running (power on engine off) it clocks in at...
  15. pkufeldt

    Misfires return

    Just an update, I re-installed the old possible lazy O2 sensor which raises the FTs and the misfires disappeared. So I am still thinking it might be the fuel pump.
  16. pkufeldt

    Misfires return

    Just re-looked at my fuel pressure test video's to get accurate numbers: Pump running, engine off: 61psi Pump off, engine off, immediately drops to 51psi and holds (there might be a small loss 51.8->51) Running at idle: 50-51psi Running at higher rpm (>2k): settles down to 50psi and holds Let...
  17. pkufeldt

    Misfires return

    1999 Suburban K1500 5.7L 133k miles I have been tracking down a long standing misfire problem with my suburban and have done many repairs and tests along the way in an attempt to fix. Here is the sequence: P0300 and P0306 DTCs appear Arbitrarily replaced plugs, wires, disty rotor and cap...
  18. pkufeldt

    Newbie Looking at O2 sensor data

    Too freakin funny. :-) I am still new enough to this and I haven't invested in a real scanner. I am using a BT Elm reader and an app on my tablet. I am using Car Garage Pro and it doesn't look like I can reset the FT. But disconnecting for an hour seemed to work. LTFT went to 0.4 and sat...
  19. pkufeldt

    Newbie Looking at O2 sensor data

    Just disconnected my battery to reset FT, thank you. About the cats. My bad, I knew there were 2 cats, just wrote it up wrong. Was mostly suspicious about the cat off bank2 cause downstream sensor seems to follow upstream. But cat off bank1 looked different and made me wonder about the...
  20. pkufeldt

    Newbie Looking at O2 sensor data

    Pretty sure I have wrecked my cat but I thought I would post something and see if anyone could help confirm. Just finally fixed a long standing misfire stemming from a worn distributor. As part of diagnosing the misfire, before I figured out it was the distributor, I replaced the stock SFI...

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