1989 K3500 ran fine, now won't even stay alive without pumping gas pedal... Stumped.
Thread Starter
CF Beginner
Joined: Jun 2019
Posts: 7
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Guys,
thanks for the help. I got the truck running for a day and have made a new post with updates as another issue has appeared. Check it out here: https://chevroletforum.com/forum/198...23/#post431843
thanks for the help. I got the truck running for a day and have made a new post with updates as another issue has appeared. Check it out here: https://chevroletforum.com/forum/198...23/#post431843
CF Beginner
Joined: Aug 2024
Posts: 1
Likes: 0
Hello, new to the forum so please excuse any ignorance.
I bought an '89 K3500 (7.4L 454) last week and it was running great at first- I ran it up one of my local canyons to test the engine and experienced intermittent loss of power at high speeds, which got worse until the truck stalled out when I came to a stop. Was able to get it started, but it would only stay alive when I pumped the gas pedal. Weirdest thing. Was finally able to sputter it to the nearby Chevy dealership pumping the accelerator (oddly enough, the engine seemed to fire briefly when I let off of the accelerator, and I had to keep pumping to keep this up), and they ran a diagnosis and said that it has fuel pressure, but that the injectors were dumping fuel into the engine. Per their advice I replaced the injectors, plugs, plug wires, distributor cap/rotor, & ignition coil, and it still wouldn’t idle.
We then read the OBD and it said that there was an open circuit in the TPS sensor, so we replaced the connector and it still wouldn’t idle. When I took the TPS sensor out to replace, the screws were broken off inside the screw hole- but the strange thing is that the car still won’t idle or stay alive without me pumping the gas, and I don't believe you need a mounted tps to do either, as long as the arm is in the right place on the sensor.
I feel like we are one part or adjustment away from this thing running solid but need some advice from someone who knows the model better, because google has led me down multiple rabbit holes. Any suggestions on what to look at?
I bought an '89 K3500 (7.4L 454) last week and it was running great at first- I ran it up one of my local canyons to test the engine and experienced intermittent loss of power at high speeds, which got worse until the truck stalled out when I came to a stop. Was able to get it started, but it would only stay alive when I pumped the gas pedal. Weirdest thing. Was finally able to sputter it to the nearby Chevy dealership pumping the accelerator (oddly enough, the engine seemed to fire briefly when I let off of the accelerator, and I had to keep pumping to keep this up), and they ran a diagnosis and said that it has fuel pressure, but that the injectors were dumping fuel into the engine. Per their advice I replaced the injectors, plugs, plug wires, distributor cap/rotor, & ignition coil, and it still wouldn’t idle.
We then read the OBD and it said that there was an open circuit in the TPS sensor, so we replaced the connector and it still wouldn’t idle. When I took the TPS sensor out to replace, the screws were broken off inside the screw hole- but the strange thing is that the car still won’t idle or stay alive without me pumping the gas, and I don't believe you need a mounted tps to do either, as long as the arm is in the right place on the sensor.
I feel like we are one part or adjustment away from this thing running solid but need some advice from someone who knows the model better, because google has led me down multiple rabbit holes. Any suggestions on what to look at?
CF Beginner
Joined: Sep 2024
Posts: 1
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I'm new here however, if you can't start the truck without pressing the gas pedal you either have a bad I.A.C. or it is is even likely that the timing chain is bad or going bad. If you take off the air cleaner and have someone bump the starter on the truck and see if you are getting a backfire or a cloud of smoke puffing out of the intake. If so, it would be the timing chain has stretched and there is too much slack in it. There will also be a delay in the turning of the rotor button which you can clearly see if u remove the dizzy cap and attempt to start. If all is good in these areas I would say it's definitely something going on with your I A.C
