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Matt, Engineer
Category: Chevy
Satisfied Customers: 21607
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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2000 Chevy Impala LS 3.8 V6 Had chugging and stalling

Customer Question

2000 Chevy Impala LS 3.8 V6 Had chugging and stalling problem MAF was changed and solved problem for a couple weeks. Problem started again, now car is dead. It will turn over but will not start. All spark plugs have been changed. Car does not run with MAF disconnected or connected.
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
Once the car died, it was able to be started once more but died immediately.
Expert:  Matt replied 1 year ago.


this sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank.

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,

Ideally measure the pressure at the injectors and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

Customer: replied 1 year ago.
The fuel pump is coming on when the car tries to turn over. We can hear that. The connections are clean, and recently replaced as well. All pressures at the injectors are running sufficiently.Fuel filter is getting changed now.
Expert:  Matt replied 1 year ago.


OK in that case this could be incorrect fuelling due to a faulty water temp sensor. If this is the problem then the ECU will be leaving the car constantly ' on choke' and not reducing the fuelling as the engine warms - so unplug the sensor and clean the contacts on both sides with some switch / electrical cleaner (not WD40) and inspect the wiring for any signs of damage to the insulation especially where it runs over other components and through the bulkhead- if this doesn't help consider replacing the sensor as they're not expensive

Customer: replied 1 year ago.
CTS water pump AND the radiator were all replaced before this winter. Nothing appears to be corroded or dirty. Trust me, coming here for answers was last resort as we do not want to head to a mechanic.
Customer: replied 1 year ago.
Just another side note, it is not flooded with gas either.
Fresh oil change and new filter was done about 250 miles ago as well.
Customer: replied 1 year ago.
Seems to be getting, spark compression and fuel but not starting.
Expert:  Matt replied 1 year ago.


Ok thanks for the extra information

I'd say that this could be a faulty crank position sensor but before just replacing it also check for a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter

Crank position sensor

Cam position sensor

O2 sensor

Throttle position sensor

unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.

Customer: replied 1 year ago.
Ok, we will check all of these and let you know how this process has gone.
Expert:  Matt replied 1 year ago.


good luck

Expert:  Matt replied 1 year ago.


do you still need help?

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