Oil pressure senders failing (Page 3/3) Raydar MAR 14, 07:04 PM quote Originally posted by tmadia: Today I got home from a short trip (in a different car) and when I walked by the Fiero I heard the buzzing of the fuel pump. The sender failed in such a way that the fuel pump was running continuously even without the key. ... I had a brand new sender to do exactly the same thing. (My previous sender killed the battery when it stuck, and kept the pump running.) I finally got tired of the silliness, and moved the fuel pump fuse circuit to the "ign" side of the fuse box, instead of the "batt" side. (Involved a bit of cutting/splicing/soldering behind the fuse box.) If you have a high current / high volume pump, this might not be advisable, but on my installation, it has never caused me a moment's trouble. Patrick MAR 14, 07:34 PM quote Originally posted by Raydar: I finally got tired of the silliness, and moved the fuel pump fuse circuit to the "ign" side of the fuse box, instead of the "batt" side. (Involved a bit of cutting/splicing/soldering behind the fuse box.) Not trying to totally derail this thread , but I'm wondering if that might also be a good idea for the '84-'86 headlight motor circuit? Might prevent a dead battery... or worse. armos MAR 14, 09:25 PM quote Originally posted by RWDPLZ: Crappy oil pressure sending units have been a problem in these cars for decades, they're probably all made by the same supplier that has been doing it wrong for a LONG time. There's at least 2 different sources for the 88 style sender, because I've had a few BWD senders that gave low pressure alarms at a hot idle (incorrect per comparison with mechanical gauge), and 3 Delcos that all gave valid readings. There's a distinct difference in how the 2 brands are calibrated. I agree they're all unreliable though. The one nice thing about the 88 style is that it's easier to change (it's skinny enough you can put a socket over it). Other than that I'm not sure it was a good idea to convert, but I already did it. I'll never know if the older style would have been as failure prone as the 88s have been. Apparently I haven't had near as much trouble as some people here though. Mine have lasted a few months to years each, not days to weeks like I'm reading here. If there's any external factor causing these things to fail faster for some people, then this is all I can come up with: are you using dialectric grease on the electrical connector to keep water out? is your charging system working properly? Check voltage with a multimeter, look for high voltage excursions. Check your peak (cold) oil pressure with a mechanical gauge. I don't remember if the bypass is set for 60psi or 80psi, but it definitely shouldn't go into the 100s and the sender might not be happy if it does. If you check that, go ahead and check the minimum hot idle pressure too. Then you'll know more about the health of your engine and how accurate the dash reading is at the low end of the scale. As above, I strongly prefer the AC Delco senders because they are more accurate at the low end of the scale. The BWD senders I've used were in single digits (turning on the Oil warning light) when the mechanical gauge was still showing 20s. To test the dash gauge, try plugging a resistor into the connector and see if the gauge responds correctly. I don't remember the exact scale but it's close to something like 1ohm per psi. A 68-75ohm resistor should give a near full scale reading. The exact scale might have been posted somewhere. You'll need to use multiple resistors in parallel because of the current draw - use the parallel resistor formula to get the resistance you need. Otherwise be ready for the resistor to start burning as soon as you plug it in. reinhart MAR 16, 10:17 AM I've owned 4 88 GTs and never had to replace an oil pressure sender. Not sure what is causing others to blow them up. theogre MAR 16, 07:32 PM quote Originally posted by SunsetChaser: I've checked the wiring. Initially I used the butt connectors that came with the pigtail but then I simply soldered the wires together and sealed them with heat shrink tubing. The first sensor was from ebay, the second from walmart and the last one from Rock Auto. All 3 had the same failure rate. Also I'm not sure if this is relevant but I should note that when the key is in accessory mode, the needle shows just above the red on the oil gauge (towards the left). It's only when I crank and start the engine that the needle is pegged far right until I shut the engine down. Maybe a clue as to how they might be failing? Gauge pegged and stays is usually open something on the sender and wire between them. Saying Rock Auto is meaningless because have different makers and PN even by same brand like Standard has xxx and xxxT w/ T numbers is cheaper and days of warranty. IF all senders OP section is open on a meter... (Ω meter say OL etc not 0-90Ω for A to Base.) could be crap senders or gauge have problems and frying the senders. Senders run on "12v" but not Direct "12v." A iffy gauge or a "soft" short to 12v otherwise can let too many amps flow and fry the sender. Note that the Gauge have a resistor on back of it and not covered in any service doc including FSM. That resistor could have problems and so can the dash in several places... Common Examples: Gauge resistors and "nuts" get loose, dirty, etc. Do Not over tighten or can wreck the resistor or gauge. Big plugs on back and "board" go into like to bend the copper when "glue" fails on the board. SS spring clips can have problems on the board side, bolt side holds the gauge bolts, or both. The dash gauges often lie even when have good sender because of same problems. My gauge often reads ~ 80psi even w/ 42-47Ω resistor to emulate ~ half scale sender. Check the dash and even Replace the gauge didn't help. Something else in gauge wiring is loose etc but not digging thru the entire car to find whatever is wrong. theogre MAR 18, 02:49 PM And most gauges runs off gauge fuse and should not have power when key is in acc.