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TPI fuel regulator

Discussion in 'The Injection Section' started by tunedportk5, Mar 17, 2005.

  1. tunedportk5

    tunedportk5 1/2 ton status

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    I need to get the fuel presure up from 38 to 42 maybe higher to get rid of the lean reading on the O2 sensor. I was just going to get a ajustable regulator but the guy at Summit told me this part is not smog legal for California and that may be a problem cause I need to take the truck to the refree still and they might look at that. And my queston is a ajustable regulator illeagal to use, or is there a diffrents between the 305 and 350 regulator. I did get TPI setup off a 305 but the numbers on the injectors say they are off a 88 350, and maybe it just has a 305 regultor?
    :confused:
     
  2. Fierospeeder

    Fierospeeder Banned

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    whats your fuel pressure spec for that vehicle?

    is your long term fuel trim saying your running lean?
     
  3. tunedportk5

    tunedportk5 1/2 ton status

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    A 305 is 38 and a 350 should be 42.

    when I'm on the freeway the check engine light comes on and its for a lean o2.

    so I hook up a volt meter and most of the time it around the 2 volt range.
     
  4. Fierospeeder

    Fierospeeder Banned

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    usually,narrow band o sensors only make up to 1 volt


    If it only happens while on the freeway. I would look into the EGR system, evap, and air. See if those systems are working correctly.
     
  5. tunedportk5

    tunedportk5 1/2 ton status

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    according to my volt meter its always on the lean side even on city streets
     
  6. Fierospeeder

    Fierospeeder Banned

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    what kind of a multimeter?

    lean is anything below .5 volts

    oxygen sensors are better read on a labscope.


    The oxygen sensor jumps from rich to lean all the time. If your vehicle is running lean it would be jumping from .1 to .6 and the computer will try to compensate and get it back to .2-.8


    If your oxygen sensor is always staying at a certain voltage. It is either broke or it isn't getting hot enough.
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Like he said "check the EGR". Also check for Vac leaks. Both can cause that. The plastic Vac lines are real bad about getting brittle. I would start there. Put a vac gage on the EGR and verify its open at steady cruise. At full throttle the system goes open loop. It goes back closed loop at steady cruise above 1300 or so RPM. So for you to get a lean code you have ot be sampling at cruise. The EGR purpose is to cool the combustion chamber. The O2 may perceive lack of this cooling as a lean condition. Depending on the year it will either throw a EGR code or a Lean code or possibly both.

    You should be able to press up on the diaphragm while it idling and open the egr manually to verify the pintle is not clogged. It should stumble and possibly stall with the EGR open at idle. You could also give it manifold vacuum at idle and check it that way. Many of the EGR's GM uses cannot be checked with a hand operated vac pump like a mighty VAC. The EGR are bleed style. You cant pump fast enough to get them to open if they are.
     
  8. Fierospeeder

    Fierospeeder Banned

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    you mean they have a transducer

    you stick a few rags in the exhaust to create backpressure, and you should see the EGR starting to operate. :cool1:
     
  9. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    adjustable fuel psi regulater eh?
    I bought one for around $60 for my tpi. it's nothing more than the stock regulator cap with a hole drilled and tapped for a machine screw. Before you put it back on you stick a quarter or a electrical box slug on top of the fuel regulator diaphram... you can turn that machine screw in and it will increase the fuel psi.
    I couldn't believe what i spend 50 or 60 bucks on when i could have made it myself for like a buck.
     
  10. tunedportk5

    tunedportk5 1/2 ton status

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    I have all new vacuum lines so that should be ok ,I'll check the egr valve but I'm still wondering if the ajustable regulator will pass the refree inspection.
     
  11. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I wouldn't worry about it being smog legal. Every manufacturer says that about anything that is part of a smog device so that they can't be held accountable. The adjustable regulator is no big deal, and as Ryan said just remove the cover and drill and tap it for a small machine screw and then install a piece of steel about the size and thickness of a quarter then reinstall the cover and adjust fuel pressure. When i had my TPI i had mine adjusted right about 45 PSI and it ran great.
     
  12. tunedportk5

    tunedportk5 1/2 ton status

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    OK cool I'll try that it seem Like a quick fix, next thing I need to do is figure out why I'm still getting a code for MAF burn off circut after buying a new one.
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Because MAF systems suck. They don't like dirt or vibration of which our rigs are subjected to both. Maybe the MAF is bad AGAIN?
     
  14. Fierospeeder

    Fierospeeder Banned

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    MAF is great for EFI.

    But the first generations of MAF really sucked on GM cars.
     
  15. tunedportk5

    tunedportk5 1/2 ton status

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    going to check for faulty wires on the MAF then exchange it if they check out, I wish I knew MAF sucked before I bought the wiring harness I would of got the MAP setup.
     
  16. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Some people on here will tell you that MAF is better and that they run it with no issues but if you understand the things that MAF systems don't like and then realize that we subject them to those exact things you would have made a different choice. Don't get me wrong, MAF is better than MAP when it comes to performance mods such as hot cams but not when subjected to vibration and dirt. You will soon find out that replacing MAF sensors gets old and VERY expensive. IMHO you would be better converting to a MAP system instead of putting anymore $$$ into the MAF system. Just my .02
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    Here's the GM code 36 (MAF burnoff) troubleshooting flow chart that Vader over on thirdgen typed up. If you aren't following these, you'll waste a lot of time and money throwing parts at the problem.

    [font=Verdana, Arial]"You'll need a voltmeter.

    • Clear codes.
    • Ground diagnostics terminal.
    • Start engine and wait for the check engine light.
    • Unground terminal.
    • Shut off car.
    • Wait a minute or so.
    • Restart car for 20 seconds or until check engine light comes on.
    • Shut off car.
    • Turn ignition to ON position.
    • Check for codes.
    • No code, problem intermittent.
    • Code 36, unplug burnoff relay, check both orange wires for power.
    • If one or both have no power, repair open circuit.
    • If both orange wires have power, reconnect relay.
    • Disconnect MAF sensor.
    • Ground burnoff relay black wire, terminal "F".
    • Check MAF connector terminal "D" for power.
    • If no power, replace burn off relay.
    • If it has power, with relay terminal "F" still grounded, check MAF plug terminal "E".
    • If no power, replace MAF power relay.
    • If terminal "E" has power, disconnect burn off relay.
    • Check burnoff relay black wire (terminal "F") for power.
    • If it has power it is shorted to power somewhere. If it has no power, suspect ECM or ECM connector.
    • Code 36 can be caused by a bad connection at either relay.
    • Check relay connector contacts for corrosion and tight fit before replacing ECM.
    That's from the service manual. It might get you closer to the problem. One key is that BOTH relays need to be intact. The MAF signals the ECM and must get power through the normally closed sontacts of the MAF Power Relay during the burn off cycle, so the MAF power relay is still a suspect."
    [/font]
     
  18. Blue85

    Blue85 Troll Premium Member

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    Remember that the hole you are drilling in the cap of the regulator has vacuum behind it, so you have to seal it up. I did this and mod and used a collapsing "blind nut" to hold a "set screw" bolt that has a small square head. There isn't much room between a TPI regulator and plenum. It works good for me.
     

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