Olds 3.8 fires then dies

Messages
3,118
Location
San Antonio, TX
After several attempts, the engine runs well. At the next startup, neighbor has to go through the same fires then dies routine all over again. Cracked coil pack, sparkplug cables and sparkplugs were recently replaced. Has anyone traced this problem before?
 
Messages
887
Location
LI, NY
Fuel pump resistor. Some of these car had a two speed fuel pump for quiet operation. Easy enough to check via fuel pressure.
 
Messages
35,998
Location
ME
Speaking of the fuel pump some of these cars power the fuel pump through the oil pressure warning sender. They prime the pump for starting with a relay that is then deactivated. Listen for it.
 
Messages
588
Location
Chicago, IL
I think they only used the fuel pump resistor on the supercharged versions of that engine. Could be wrong. But yeah, if it has one, that is how it acts when it fails. It primes the pump on "full speed", and then switches to "half speed" through the resistor when the engine starts. If the resistor is blown, the car will only run on the residual pressure for a few seconds. You can test this by starting the car and then flooring the gas right away. If the car will keep running while its floored, and then die when its not, that's the problem. You can work around this by finding the "fuel pump speed" relay and bend one of the pins back. If I remember right, when the relay is energized, it runs the pump at half speed. So if you bend back one of the coil pins on it and reinstall it, the pump will run at full speed all the time. This will get you moving so you can get to a dealer to get the kit to fix the resistor.
 
Messages
998
Location
Lexington, SC
CPS as above or the coolant tenp sensor is the problem. The car acts like a 'bad choke' would in the days before FI and computers. The coolant temp sensor has to tell the computer that the engine is cold and to go to cold run mode, ie rich. A defective temp sensor won't give the proper signal to the PCM so it thinkx the engine is hot and therefore tries to run too lean, causing the rough run problems.
 

jorton

Thread starter
Messages
3,118
Location
San Antonio, TX
 Originally Posted By: Scimmia
Just what car/year are we talking about, anyway?
94 Olds 88. CTS measured 190 [email protected] and 190 ohms after we drove the car for 10 minutes. Per the Haynes manual the difference should be approximately 500 ohms.
 
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