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  1. D

    No power at highway speeds

    Well, it's doing better, but not 1oo% yet. Got a smoke tester and the only smoke I'm seeing in the vacuum system is coming from the throttle body most likely from the IAC area. Is this normal or should the IAC pintle be sealing this area off? I replaced all the vacuum line under the hood with...
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    Cruise Control Release Switch

    Unfortunately, I threw away the original without thinking when it was bad and I ordered the new one. And Jgonick, that's correct. Both the brake light and cruise are connected to the brake light switch. As long as the vacuum part of the switch works I assume it should be ok, just checking if...
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    Cruise Control Release Switch

    My cruise control release switch went bad a few months ago and I replaced with a different style which was the only thing available and it didn't last at all. The switch that was on the truck was a black GM style with only a vacuum line connection. GM part #407437. The only thing available at...
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    No power at highway speeds

    Well, I found a vacuum leak at the cruise control release switch at the brake pedal and it appears the vacuum hose at the manifold may be collapsing. I replaced the hose at the manifold, but have to wait for new switch to come in. Thanks for the help
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    No power at highway speeds

    Ideas on locating possible leak? At using port on throttle body the vacuum gauge doesn’t move so if I have a leak it’s only showing at higher rpm’s. I’ve checked all hoses in engine bay. I’ll bypass the cruise servo to see if it’s internal of that but any other ideas? Besides modulator on tranny...
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    No power at highway speeds

    Is that normal on these to close blend doors at higher rpm’s? Or is it because I’m losing vacuum and it can’t hold the blend door open?
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    No power at highway speeds

    Yes truck ran great till then. And really I guess I didn’t check if blend doors were closing or slowing down. Just noticed air flow reduced from vents. I can check that tomorrow
  8. D

    No power at highway speeds

    At my wits end. 1987 1500 305 TBI engine. A few months ago, the ICM went bad. I screwed up and broke the connector inside the distributor so I ended up replacing the whole distributor. The problem the truck is having now is that it runs great speeds in town, but I've lost all power at highway...
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    Cruise Control Servo

    Trying to rebuild the cruise servo on my 87 TBI engine. The sandpaper looking stuff that wraps around the magnetic wire just disintegrates with the slightest touch. What is this material and what would be a good substitute? And what are you all using for the filter material below the plunger?
  10. D

    Oil in throttle body

    It's definitely oil. It's milky from mixing with the condensation, but it's thick like oil.
  11. D

    Oil in throttle body

    This is the amount of oil in the back of the tbi throttle body after a little over 100 miles. New PCV valve and all cylinders have 150 psi compression except for cylinder 1 has around 130. Any ideas? Can I delete this hose from the driver's side valve cover and just put in a breather or maybe...
  12. D

    backing plates. where are they?

    I got new ones for the front of my 87 from LMC. Might check there
  13. D

    Front rotor question

    1987 GMC R1500 long bed with 305. I have the JB5 code in the glove box for the bigger brakes but when the front rotors came in, the inner bearings are bigger than what came off the truck. Outer bearing and seal are same size. It appears the smaller rotors for the 2” rear shoes are the size...
  14. D

    Help identifying under dash connector

    Thanks for everyone’s assistance
  15. D

    Help identifying under dash connector

    It has D, 2, 1. No overdrive on the indicator. It also has the kickdown relay on the firewall that appears to be original due to the harness. Does the relay come with the th400, 700r4, or both?
  16. D

    Help identifying under dash connector

    I don't think so, but don't know for sure.
  17. D

    Another episode of whats this connector?

    2 plugs into #1 and I believe its the speed sensor. Connects to the cluster
  18. D

    Help identifying under dash connector

    I do have cruise control and I only see 2 plug-ins on the cruise control switch and they're both still connected.
  19. D

    TH400 Kickdown switch information...

    I'm putting the kickdown switch back in my '87 with the TH400. Last owner took the switch off the pedal and disconnected the wire from the tranny. I've read in this post that one wire goes to tranny and the other goes to ignition source in fuse box. Does none of the wires go through the kickdown...
  20. D

    Help identifying under dash connector

    One is pink w/black stripe and the other is purple
  21. D

    Help identifying under dash connector

    Yeah, it's an identical connector, but there's one already connected there.
  22. D

    Help identifying under dash connector

    Can anyone advise what this connector is for? It’s under dash near steering column. I have an 87 GMC with TH400 and someone did away with kickdown switch all together. So I’m trying to wire in a new one and found this connector under the dash but it’s spade terminals point a different...
  23. D

    Vent Door

    Yes, it switches between floor, vent, and defrost. Just haven't gotten to start on A/C yet. Thanks for the response
  24. D

    Vent Door

    Can anyone advise what control setting is supposed to open the door at the bottom passenger kickpanel on a 87 GMC? It doesn't seem to open on any setting. I have A/C, but it is currently inoperable.
  25. D

    Headlights?

    Thanks guys. Leaving town for the next week but I’ll try these suggestions when I get back.

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