When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Yep, the two-terminal switch that is screwed into the head above/between #6 and #8 is for the electric fan and the switch that is above/between #1 and #3 is the temperature sender for the gauge. The switch above the oil filter is for the engine oil temperature and the switch at the front/right of the intake manifold is for the temperature sensor for the ECM. The BIG switch next to the distributor is for the oil pressure and it also turns on the fuel pump relay.
you got me, I stopped buying books when I had to stop studying for stuff for examinations
maybe, I have no excuse, maybe the costs? lame reason...
Compared to the expenses of buying parts that are not need for the problem, and the time spent chasing ghosts, the FSM is cheap. Not to mention how much easier it is to simply FIND which switch/sensor is at that particular spot.
No, it doesn't. There is a pressure switch that connects from +12V to the fuel pump. But, the ECM ALWAYS energizes the fuel pump relay when the engine is turning over (cranking or running). So, the only conceivable purpose for the pressure switch is a backup to the relay.
Pretty much every early GM fuel injection systems had that pressure switch and you could disconnect or remove it without affecting the operation.
No, it doesn't. There is a pressure switch that connects from +12V to the fuel pump. But, the ECM ALWAYS energizes the fuel pump relay when the engine is turning over (cranking or running). So, the only conceivable purpose for the pressure switch is a backup to the relay.
Pretty much every early GM fuel injection systems had that pressure switch and you could disconnect or remove it without affecting the operation.
I agree and dis agree.
If you're not showing oil pressure the fuel pump is shut down. The ECM goes thru a priming cycle when the key is turned on. That's enough to start the engine and show oil pressure. Without that circuit being complete the ECM will kill the fuel pump relay. I guess a jumper could solve this but it's just as easy to install the correct oil pressure sending unit.
I agree and dis agree.
If you're not showing oil pressure the fuel pump is shut down. The ECM goes thru a priming cycle when the key is turned on. That's enough to start the engine and show oil pressure. Without that circuit being complete the ECM will kill the fuel pump relay. I guess a jumper could solve this but it's just as easy to install the correct oil pressure sending unit.
You can find lots of people claim it works that way, but they don't know what they're talking about. They see the OPS in the wiring and just ASSUMe it works that way (why else would the switch be there, right?). You can unplug the OPS as long as the fuel pump relay is working. Same applies to all the other GM injection systems through the early to mid 90's that have the OPS. Eventually, GM began to drop the OPS and rely on the relay only.
Interesting. My GM Shop Manual for my '82 specifically lists a pressure switch that disallows ignition until it reads a minimum pressure (4PSI, If I remember correctly) thus all the extra cranking when the car has sat for awhile before starting. I always assumed it was meant to prime the motor (lubricating cam, lifters, etc.) with oil prior to ignition.