89 R3500 7.4l oil psi/fuel cut-off switch location

[SCOTI]

Where does the oil pressure switch for the fuel pump go on a 7.4l bbc w/TBI? My assumption is a boss located on the driver side toward the front of block tucked behind the power steering pump set-up. I want to confirm this if possible.

Pics are always good if someone has them as well.

Thanks in advance!

[rfmaster]

TBI system uses oil pressure switch as a back-up for a fuel pump relay. This switch is located in the back of the engine, to the left side of distributor. Usually there is a 90 deg brass riser into which oil pressure switch screws into. Depending on truck options it may have a three wire plug which should have gray, orange and brown color wires.

//RF

[SCOTI]

Originally Posted by rfmaster

TBI system uses oil pressure switch as a back-up for a fuel pump relay. This switch is located in the back of the engine, to the left side of distributor. Usually there is a 90 deg brass riser into which oil pressure switch screws into. Depending on truck options it may have a three wire plug which should have gray, orange and brown color wires.

//RF

This is what I've found doing Google research which is what propmted me to ask the question.

When I pulled the motor from my truck, I labeled most of the plugs/wires; some better than others. Where this 'plug' is on the 'engine' wiring harness is around the same location as the a/c compressor plug (front driver side of the motor). There's definitely not enough wire for it to reach the rear of the block. I also tagged it as 'crank front/side'.

I couldn't remember where the switch originally went because the machine shop pulled it off & just tossed it in my used parts box w/the old p-rods, rockers, & stuff. The threads for the 'switch' seem to match the threads for that front port as well & it's @ the crank centerline of the oil pan rail.

Was the location for these the same on sbc's & bbc's?

[clinebarger]

Originally Posted by SCOTI

This is what I've found doing Google research which is what propmted me to ask the question.

When I pulled the motor from my truck, I labeled most of the plugs/wires; some better than others. Where this 'plug' is on the 'engine' wiring harness is around the same location as the a/c compressor plug (front driver side of the motor). There's definitely not enough wire for it to reach the rear of the block. I also tagged it as 'crank front/side'.

I couldn't remember where the switch originally went because the machine shop pulled it off & just tossed it in my used parts box w/the old p-rods, rockers, & stuff. The threads for the 'switch' seem to match the threads for that front port as well & it's @ the crank centerline of the oil pan rail.

Was the location for these the same on sbc's & bbc's?

On that year BBC its on the left front pan rail..pic.

On a SBC its behind the distributor or above the oil filter pad.

[SCOTI]

Originally Posted by clinebarger

On that year BBC its on the left front pan rail..pic.

On a SBC its behind the distributor or above the oil filter pad.

Excellent. Thanks for that pic/schematic as it brings a secondary question to the table....

#41 in the pic indicates its the 'water temp switch'. Anyone know specifically what this is as there's another water temp sending unit that was in the middle of the pass side head? I'm guessing one is for the ECU while the other is for the gauge?

[Shyguy]

#41 on my '92 K-3500 with a 454 is for the temperature gauge. The one in the passenger side head is for the auxiliary fan in front of the radiator.

[SCOTI]

Originally Posted by Shyguy

#41 on my '92 K-3500 with a 454 is for the temperature gauge. The one in the passenger side head is for the auxiliary fan in front of the radiator.

Ahhh. I started looking for it in the wiring schematics but haven't made it all the way through.