Engine idle issues when warm or when I drive

SEAKENJI

MEMBER
1989 CHEVROLET 2500
5.7L
V8
4WD
AUTOMATIC
215,000 MILES

The engine starts up fine but when it warms up it starts to shut off like it's getting too much fuel. If I try to drive it it keeps dogging out when I give it gas unless I floor it. I've replaced the EGR valve, the EGR cyl, the ECM, the TBI with a working junk yard one and still no luck. My Uncle replaced some other things he thought it could be. I'll try to update this but any advice would be amazing. Also there hasn't been any check engine light I replaced the bulb just to be certain.

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2 Replies

MOTOR MASTER

MECHANIC
279 POSTS

Hello my name is Dave.

My first suspect is the coolant temperature sensor, it's located by the thermostat housing. It is inexpensive and a very common problem with the early GM systems, a lot of times without a check engine light. When they go bad it will usually run decent when started but as the engine warms up and the ECM doesn't know it it due to the sensor it runs too rich.

If it was my vehicle I would replace the sensor regardless. If you can replace the sensor and let us know the results we would appreciate it. We look forward to hearing back from you and thank you for using 2CarPros!

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Thursday, February 18th, 2021 AT 4:33 AM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

The coolant temperature switch is located on the left side of the engine (driver's side) and between the first and second spark plug. See pics 1 and 2.

First, here is a link to help with the procedure:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Here are the directions for replacement specific to your vehicle:

_______________________

1989 Chevy Truck K 2500 Truck 4WD V8-350 5.7L
Coolant Temperature Sensor (CTS)
Vehicle Powertrain Management Sensors and Switches - Powertrain Management Sensors and Switches - Computers and Control Systems Coolant Temperature Sensor/Switch (For Computer) Service and Repair Procedures Coolant Temperature Sensor (CTS)
COOLANT TEMPERATURE SENSOR (CTS)
The coolant sensor must be handled carefully. If sensor is damaged, fuel injection operation will be affected.

1. Disconnect battery ground cable.
2. Drain coolant from radiator so level is below sensor.
3. Disconnect coolant sensor electrical connector.
4. Carefully back out coolant sensor and remove.
5. Reverse procedure to install.

I hope this helps. Let me know if you have other questions.

Take care and God Bless,

Joe

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