Leadfoot Posted August 12, 2014 Report Share Posted August 12, 2014 I don't know why this is causing me so much trouble. This should be simple, but I can't figure out why this has me so baffled. I have been working a bunch of hours lately and all I can figure is it's lack of sleep. 2 weeks ago (Monday morning) I start my 94 Cutlass 3.1 to go to work. It fires up and runs for several seconds before dying. I try to restart and it only cranks. I noticed when I cycle the key that I don't hear the fuel pump. Because of things going on at work, I didn't have time to try a quick diagnostic so I grabbed the keys to the GXP and went to work. I haven't really had time to mess with it because work has been so busy until tonight. The Cutlass has 226k miles and is on the original pump so the pump being bad would be no surprise, but I want to be sure before throwing parts at it. I tested the relay out of the car and it works. I tested the different wires connected to the relay and came up with the below info. 30 - Gray wire - ground with ignition on, nothing with ignition off 85 - Green wire - with ignition on very low voltage (roughly 2v and drops), ground with ignition off 87a - Red wire - nothing with ignition on, nothing with ignition off 87 - Orange wire - 12v all the time 86 - tan with white stripe - ground with ignition on, nothing with ignition off I tried the jumper wire by the drivers front shock tower and got nothing from the fuel pump. I also tried jumping the fuel pump by powering the gray wire above with the relay out and got nothing. Based on results for 85, I am wondering if I have an ignition switch problem or if I am just overthinking this. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted August 12, 2014 Report Share Posted August 12, 2014 (edited) I tested the different wires connected to the relay and came up with the below info. 30 - Gray wire - ground with ignition on, nothing with ignition off 85 - Green wire - with ignition on very low voltage (roughly 2v and drops), ground with ignition off 87a - Red wire - nothing with ignition on, nothing with ignition off 87 - Orange wire - 12v all the time 86 - tan with white stripe - ground with ignition on, nothing with ignition off HOW did you test the wires at the relay--relay installed, or relay removed? I tried the jumper wire by the drivers front shock tower and got nothing from the fuel pump. Was the relay installed? I also tried jumping the fuel pump by powering the gray wire above with the relay out and got nothing. I haven't looked into fuel pump wiring for over a year...but I'm thinking the tan/white wire actually powers the pump. You should verify and re-test. Based on results for 85, I am wondering if I have an ignition switch problem or if I am just overthinking this. Relay installed? I do remember figuring out that the whole circuit from battery auxiliary stud to the pump itself it plagued with voltage drop because GM used undersized wiring. I lost over a volt on the positive side, and over a volt on the ground side due to GM using 16 gauge wire where 12 gauge would be recommended. Edited August 12, 2014 by Schurkey Quote Link to comment Share on other sites More sharing options...
Heartbeat1991 Posted August 12, 2014 Report Share Posted August 12, 2014 If the jumper does nothing, it's the pump. The relay doesn't need to be installed for the jumper to work. The jumper should provide power right to the pump. Quote Link to comment Share on other sites More sharing options...
Leadfoot Posted August 13, 2014 Author Report Share Posted August 13, 2014 HOW did you test the wires at the relay--relay installed, or relay removed? Was the relay installed? Relay was removed I haven't looked into fuel pump wiring for over a year...but I'm thinking the tan/white wire actually powers the pump. You should verify and re-test. I verified a few minutes ago that it tan/white is a good ground. Relay installed? I do remember figuring out that the whole circuit from battery auxiliary stud to the pump itself it plagued with voltage drop because GM used undersized wiring. I lost over a volt on the positive side, and over a volt on the ground side due to GM using 16 gauge wire where 12 gauge would be recommended. I have had intermittent problems starting the car where I get a click sometimes rather than the starter actually turning the engine over. The difference was a voltage drop to 6v instead of 11 or so when the car actually started. This is partially why I think I have an ignition problem and want to verify that the pump is indeed bad. The battery is basically dead so I am charging it tonight before I can really do any more. I did jump it and get it to start/run briefly with some starting fluid. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted August 13, 2014 Report Share Posted August 13, 2014 (edited) If the jumper does nothing, it's the pump. Or there's a broken wire to the pump/sending unit. Or there's a corroded connection to the pump/sending unit. Or there's a corroded connection inside the pump/sending unit Or there's a popped hose or perforated tube inside the pump/sending unit. Or there's a broken wire between pump/sending unit and ground Or there's a corroded connection between pump/sending unit and ground The relay doesn't need to be installed for the jumper to work. The jumper should provide power right to the pump. I don't think that's correct...but I haven't looked at the fuel pump schematic in over a year. Edited August 13, 2014 by Schurkey Quote Link to comment Share on other sites More sharing options...
Leadfoot Posted August 15, 2014 Author Report Share Posted August 15, 2014 Alright. Had a little time away from work on my "day off" to mess with this some more. The Green with White stripe is supposed to be powered by the ignition to energize the relay. It gets less than 1 volt when the ignition is on. If I jump 12v to this wire, the relay engages and sends power down the gray wire to the fuel pump, but the fuel pump still does not come on. This leads me to believe the pump is indeed bad, but it puzzles me why this ignition problem would show up at the exact same time. Any thoughts why this would happen at the exact same time? I have a feeling that I am going to get a fuel pump and that won't fix it. It seems that is how my luck has been going lately. Quote Link to comment Share on other sites More sharing options...
Leadfoot Posted September 2, 2014 Author Report Share Posted September 2, 2014 Alright. Finally replaced the fuel pump over the weekend. That was it. Of course many of the rubber sections of line are in terrible shape. I am going to drop the tank again and replace the ones I did not have fuel line for. I have to drop it anyway since the gasket that came with the fuel pump was garbage and leaks when I fill it up. I have purchased fuel line to replace all of the lines. The only one I have not gotten is the rubber line from the hard filler neck to the gas tank. Looks to be a couple inches in diameter. No one shows this piece or fuel line in that size. Has anyone replaced their before? What with? Quote Link to comment Share on other sites More sharing options...
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