1989 K3500 ran fine, now won't even stay alive without pumping gas pedal... Stumped.
#1
1989 K3500 ran fine, now won't even stay alive without pumping gas pedal... Stumped.
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?
#2
CF Monarch
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?
Last edited by oilcanhenry; June 24th, 2019 at 4:25 PM.
#3
#4
CF Monarch
If its not fuel then it has to be ignition or electrical. Hoping your ECM is okay, Those arent cheap.
Is everything else clean? MAF, Air-cleaner, PCV valve, fuel filter? Any chance something like water is in the gasoline?
Any way it might be a vacuum leak or a bad EGR valve? Is it getting a good spark? (i know you replaced the cap and rotor)
Trying to rule these out as much as possible.
Last edited by oilcanhenry; June 25th, 2019 at 9:38 PM.
#5
I'm here for the party
89 shouldnt have a MAF and fuel pressure should be max of 12 min of 9.
Troubleshooting sensors and how to test
a faulty or poor connection for C.T.S. would dump too much fuel. even a poor ground will mess up the signals
Troubleshooting sensors and how to test
a faulty or poor connection for C.T.S. would dump too much fuel. even a poor ground will mess up the signals
#6
CF Monarch
89 shouldnt have a MAF and fuel pressure should be max of 12 min of 9.
Troubleshooting sensors and how to test
a faulty or poor connection for C.T.S. would dump too much fuel. even a poor ground will mess up the signals
Troubleshooting sensors and how to test
a faulty or poor connection for C.T.S. would dump too much fuel. even a poor ground will mess up the signals
ACDELCO 2133205 {#19106672, 2134662, 88864353} Professional
My company used to own an 1989 K-1500 with a 5.7 liter, so I know I am accurate.I am a stickler about them, even though its not likely the
issue here.
I made the mistake of putting a K&N oiled air-filter on my 1998 K-1500. Big mistake and I was lucky that a good cleaning of the MAF brought it back
to life. Now it's AC Delco only air-filters
Something else is going on withjustintuah's K-3500, I just want to cover all the bases to find out what is wrong.
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#8
CF Monarch
That said I hope that we can still help this man out on his 1989 K-3500's issue with his Chevrolet pickup.
Last edited by oilcanhenry; June 26th, 2019 at 7:31 PM.
#9
I'm here for the party
water under the bridge, lets fix this truck. we all make mistakes, OCH knew what he was talking about as the part numbers he posted are for the MAP he just called it the wrong name.
#10
Justintuah - I’m not clear on the status of your problem after you replaced the TPS sensor. Are you saying you still have to “pump the gas pedal” to keep it running? Or is it just not idling well and you have to move throttle off idle to keep it running?