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  1. G

    1987 TBI Rough Idle Help!

    if you get ALDL Droid app and a Bluetooth cable for the ALDL, you don't need to install a tach. although the data stream is pretty slow, it will usually show the jumpy tach. it's basically a scan tool that let's you see what the computer sees at the sensors, fuel trims, etc. I'd make sure you...
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    A/C only works when driving!?

    I didn't think the vents closed fully in off (like a loss of vacuum). wouldn't air still be flowing out somewhere (I think mostly the floor)? but that's a good to listen for the fan vs feeling for air flow. help diagnose the motor or the vacuum pod system.
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    A/C only works when driving!?

    strange issue. but the blower is separate from the compressor. does it happen in any setting (vent, defrost, heat)?
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    1987 TBI Rough Idle Help!

    do you have a tach, or can read the signal from a scanner? a jumpy tach could be a bad ICM ground or a plug wire touching computer wires or a bad plug wire or cap letting the spark jump to computer wires.
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    Cooling Questions and Concerns

    I've never touched the heater core lines on my 1990 burb (tbi with factory serpentine), but I will say that the heater can crank the heat out when the engine is warm. And if the AC gets too cold in summer, I only need to BARELY crack the temp slider off the coldest setting to bring the temp up...
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    1985 K10 Wiper Issues

    see if this helps
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    1987 TBI Rough Idle Help!

    I figured your fuel injection system had a computer readout? Rich is O2 values steadily near .8-.9v and the computer would be reducing the short term and long term fuel trims.
  8. G

    12v ignition switch source

    I am curious about this. Pretty sure my TBI has 12v to fuel pump always when the engine is running. Is that an issue?
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    1987 TBI Rough Idle Help!

    I've had new AC Delco wires last less than 2 years before they started letting the spark out. Just because it was recently replaced doesn't mean it is still good. With no codes being thrown and nothing odd in the sensor data (I assume), you have to start looking at other things that could cause...
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    1987 TBI Rough Idle Help!

    Higher RPM can mask other issues. I'd check plug wires for cracks, especially the wire from coil to cap. I'd check the distributor cap for cracks. I'd also check to be sure your exhaust isn't plugged up. Also check to make sure the ICM connector is in good shape, and check to make sure the...
  11. G

    1985 K10 Wiper Issues

    you should be able to bypass the delay module. the harness will plug into itself. aside from that, I'd hit up the reference library for the wiring diagram or maybe the service manual and check out the diagnostics for inop wipers. my guess is you will be busy with the multi meter figuring it...
  12. G

    87' R10 TBI 350 shuts off when driving. HeLP

    I try to only use AC Delco parts for any engine sensor or management, including the ICM.
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    87' R10 TBI 350 shuts off when driving. HeLP

    injectors ground through the ECM. follow the charts I posted earlier. check for spark. if you don't have spark, diagnose that. if you have spark, then diagnose the injectors not firing.
  14. G

    87' R10 TBI 350 shuts off when driving. HeLP

    Sounds like you are on the right track. I've had my 90 suburban for 6 years and just now feel like I have all those sorts of issues sorted out. There is a lot of things just getting to start going wrong when it's all 35yrs old, even if it has been well taken care of.
  15. G

    87' R10 TBI 350 shuts off when driving. HeLP

    I am guessing that's your problem....
  16. G

    87' R10 TBI 350 shuts off when driving. HeLP

    check for spark while cranking. if you have no spark, follow the ignition check. if you have spark, follow the injector check chart A4 this is starting to smell like an ICM going bad to me, a bad connection at the ICM, or maybe a ICM harness wire that has rubbed through somewhere.
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    87' R10 TBI 350 shuts off when driving. HeLP

    fuel pump wiring is on ECMB fuse. probably have a short to ground in the wiring for that side?
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    87' R10 TBI 350 shuts off when driving. HeLP

    did it at least flash 12 so you know the SES light is working?
  19. G

    87' R10 TBI 350 shuts off when driving. HeLP

    I've had shutoff issues on my 90, for a variety of causes. Usually I have a code or a fuse blown to help diagnose. Often a blown fuse is from a short to ground somewhere in a critical ECM circuit (ECMB or ECMI). I've had bad plug wires arcing to ICM wires causing this issue, usually it will...
  20. G

    87' R10 TBI 350 shuts off when driving. HeLP

    The oil pressure switch doesn't turn off the fuel pump if the pressure gets low. But it does serve as a backup to the fuel pump relay to send power to the fuel pump once the pressure gets to 2 or 3 psi from extended cranking or allows you to keep driving if the engine is already running. That...
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    Engine cranks, but only starts after letting off key? - I'm perplexed

    Heat can play an issue. Example - my wiper washer switch is inop below about 50 degrees. When the switch is warmer than that, it works just fine. When it gets cold, something must be contracting enough to lose contact. Because I can jumper the washer pump to ground at the delay module and it...
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    87' R10 TBI 350 shuts off when driving. HeLP

    does it ever throw a code? are any codes stored?
  23. G

    Engine cranks, but only starts after letting off key? - I'm perplexed

    ignition switch issue or maybe an issue with the crank signal wire?
  24. G

    Poping fuses when ac controls are on

    I am not clear on when the issue started, when parts were replaced, or if they corrected the issue. But seems likely there is a short to ground somewhere with the blower motor wiring because the compressor doesn't kick on in the economy settings and the air direction controls are all vacuum...
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    Anybody modify the 4x10 speaker mounts in the back?

    The dash speakers were replaced 5 years ago, with some Kenwoods I think. They haven't held up great, already a little static in the driverside dash speaker. If I replace them again, I'll go with kicker 3.5. Overall things sound fine. Windows down highway cruising is where the system really lets...

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