I just paid a local shop to replace the o ring on my oil pump pickup tube. I am now experiencing extended crank time before the engine will start. It's never failed to start but it has got me worried over the amount of time I'm having to crank on it. Any ideals on what may have been disturbed from removing the oil pan? Thanks

 

The oil pressure switch also functions as a back up for when the regular fuel pump power supply system is not functioning correctly for starting, it is also a safety feature if the engine stops running in a mishap the fuel supply gets shut down.

There may be more than one problem here. Someone needs to check why the fuel supply is not adequate for starting. Until that is repaired, the oil pressure sw is allowing the fuel pump to run , just takes a while for cranking up pressure to allow pump to get power.

 

Now at least I have a place to start. Thanks hanky

 

If they removed the starter for the repair, check that the crank position sensor connector is secure. the sensor is just above the starter. Have seen this many times.

 

This truck has a fuel pump control module located above the spare tire. The fuel pump flow control module (FPCM) is a serviceable GMLAN module. The FPCM receives the desired fuel pressure message from the engine control module (ECM) and controls the fuel pump located within the fuel tank to achieve the desired fuel pressure. The FPCM sends a 25 KHZ PWM signal to the fuel pump, and pump speed is changed by varying the duty cycle of this signal. Maximum current supplied to the fuel pump is 15 amps. A liquid fuel pressure sensor provides fuel pressure feedback to the FPCM. No disrespect intended. Just giving information.

 

Went down today and picked up a replacement fuel pump relay. Installed it and it did not make one bit of difference. I did open the door and listen as i turned the key and heard the fuel pump activate. If the cps is connected i guess i'll be dropping the spare tire. Thanks

 

Try cycling the key on & off several times to activate fuel pump w/o starting.

 

The problem turned out to be a bad connection on the crankshaft position sensor. I didn't even know there was one of them down there, I remember the good old days when everything was simple. Made an inquiry on a 1971 Cheyenne today that I have been eyeballing at a local car lot. Thanks Again