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Thread: Holley TBI issue.

  1. #1

    Default Holley TBI issue.

    I'm having trouble with a Holley TBI part #502-9. I have finished a V8 S10 for a friend and can't get it to start. It's a 94 S10 with the 5.7 TBI engine. I had him get Holley TBI part #502-9, so that more air would accommodate the rebuilt engine. It won't start unless I pour gas or spray starter fluid in the throttle body, and it runs good for a few seconds. I've tested the injectors and all 4 wires have good voltage to them. I installed a new K&N fuel filter to allow fuel to flow more freely. I cleaned out the fuel tank completely before refilling it with Shell V Power premium fuel. The Aeromotive fuel pump works and has good pressure, but the injectors aren't spraying. Both fuel lines are hooked up the the correct fittings as well. I had called Holley technical service and got some weird recommendations. I'm stumped and really need help on this please.

  2. #2
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    Default

    Did you do a TPS auto reset? Is it seeing a RPM signal?

  3. #3
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    It's not a Holley EFI system (if that's what you're implying).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  4. #4

    Default

    If you're getting fuel to the injectors, and the injectors are getting power, but the injectors aren't spraying fuel,
    then the injectors have blockage inside, or they're broken. Do they make any noise. Like they are trying to open up?

  5. #5
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    I was going to suggest removing the fuel injectors for inspection (if they're clicking).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  6. #6

    Default

    Quote Originally Posted by 81 TransAm View Post
    Did you do a TPS auto reset? Is it seeing a RPM signal?
    It isn't running, so no RPM signal. It's not the whole EFI system.

    Quote Originally Posted by Danny Cabral View Post
    I was going to suggest removing the fuel injectors for inspection (if they're clicking).
    I have heard a strange buzzing. The other guy I had over here helping with some diagnostics said one injector had a small drip, but the other wasn't opening. Does this happen with brand new Holley injectors and TBI units often?
    I heard a slight buzzing or clicking if that's what it's called. What would I be looking for on the injectors and is there a way to clear the blockage? I'm going to take the injectors off and check the tip for corrosion, or possibly a piece of dirt.

  7. #7
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    Quote Originally Posted by situation5 View Post
    Does this happen with brand new Holley injectors and TBI units often?
    No, of course not. But depending on how long they sat on the shelf, the lubricating paste could've hardened, causing the blockage.

    Quote Originally Posted by situation5 View Post
    It isn't running, so no RPM signal. It's not the whole EFI system.
    He means an RPM signal while cranking to start.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  8. #8

    Default

    Okay, I took off the injectors. I didn't see anything wrong with the injectors as they seemed to look normal. They're definitely getting fuel to them, but not opening. I smelled fuel in the fuel bowls where the injectors sit. IDK why Holley technical service told me when I called before, to add a return line and add an inline fuel pressure regulator. And that it isn't possible to adjust the fuel pressure on this TBI unit. I really am at a loss, as this is all that's stopping it from running now.
    Last edited by situation5; 07-12-2018 at 03:49 AM.

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