Checking oil and fuel pressure, 96 Sonoma 4.3 (Page 1/1) 2.5 NOV 06, 02:05 PM 96 Sonoma 4.3 automatic Zr2, 146k miles. I want to check oil pressure and fuel pressure with a stand alone guage. Long story is my truck died on the side of the road, it blew the fuel pump fuse. A shop checked things and determined the oil pressure sender was drawing too many amps, and is on the same fuse as the fuel pump. So they replaced the oil pressure sender. Now my oil pressure on the guage reads low. It maxes out at only 25 on the guage no matter the rpm. Before the truck died and they replaced the sender it read 35-45, even 50-55 when the oil was cool, ambient temp. (10w30 oil). They say its possible -the guage was reading high before, while it was malfunctioning, and that 25 could be my real oil pressure... -or the fuel pump is weak due to being damaged while it was starved for power when the oil pressure sender was sucking too much power, thus the fuel pump is now sucking too much juice and starving the new oil pressure sender (so the sender reads low on the guage). Any other thoughts? Id like to check these pressures myself. The shop is many miles from me. Do I need a special separate gauge for oil and for fuel, to check these, also dont know where to hook them up, etc. jaskispyder NOV 06, 03:40 PM I would think you can use any fuel/oil/generic pressure gauge. I have a cheap dial PSI guage that I connected to a pipe and threaded that were the oil pressure sensor goes. For the fuel pressure, do you have a Schrader valve you can connect to? carnut122 NOV 06, 04:12 PM Fuel pressure gauges are under $20 at Harbor Freight. I suspect the same gauge can be made to work for oil pressure with the right fittings. cmechmann JAN 09, 07:45 PM That sending unit has a switch for, light and/or fuel pump RELAY(not connected directly to pump) and a diaphram for the gauge. The dashes came with 60 lb and 80 lb oil gauges meters. If you put in a sending unit for a 80 lb gauge on a 60 lb dash meter it will read too high. If you put a 60 lb sending unit on an 80 lb dash meter it will read too low. They send fuel pump relay feed through in case oil pressure drops out, shutting down the engine. If someone has wired the sending unit directly to fuel pump feed it will fail again. It should be only giving power to the coil in the fuel pump relay.