I'm rarely stumped, but this one has me buffaloed.
I replaced the wiring harness on my 1988 Formula with one from a 1987 GT after rodents had eaten some of the wiring. The only difference in the harnesses are the alternator, which I changed to a single wire configuration, and the oil pressure sending plug and sender unit.
With the original sender and wire, the car was fine, but when the oil pressure gauge started jumping about I knew it was time for a new sender. I took this opportunity to upgrade to the 1988 version.
I wired the Orange/Black wire to terminal C, the Tan Wire to Terminal A, and the Tan/White wire to terminal D....So why is the fuel pump running all the time now?
BTW, I changed the relay, it's new as well. One thing I noticed is water in the top of the sending unit, the rubber gasket may not have sealed very well so is it possible a short happened? Fuses are fine.
[This message has been edited by Toddster (edited 06-27-2021).]
I found the problem....Yep, a BRAND NEW sending unit and it is crapola. I swapped it out with a unit from a project car I have and BOOM, works like a charm. I knew it could not have been ME!
Anyway, live and learn. Cheap parts are cheap for a reason.
If you dislike the new Mexican GM sensors, and trust your fuel pump relay, then you will not need the redundancy of two fuel pump circuits. In that case you can just use a simple two lead oil pressure gauge sensor or add the redundancy with a second relay mounted in parallel next to the OEM unit. We have seen a lot of batteries go dead with NEW defective oil pressure sending units. In some cases they pinned the needles on the oil pressure gauge.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
My experience with 3 different sensors was a Standard Ignition sensor blows fuses, an ACDelco keeps the gauge pegged and the fuel pump running, and another ACDelco blows fuses. New relay didn't resolve any issues except that the fuel pump would shut off with the ignition. I'm running with the sender unplugged and the gauge pegged and plan to go back to the old style sending unit.
[This message has been edited by fierofool (edited 06-28-2021).]
If you dislike the new Mexican GM sensors, and trust your fuel pump relay, then you will not need the redundancy of two fuel pump circuits. In that case you can just use a simple two lead oil pressure gauge sensor or add the redundancy with a second relay mounted in parallel next to the OEM unit. We have seen a lot of batteries go dead with NEW defective oil pressure sending units. In some cases they pinned the needles on the oil pressure gauge.
It is worth consideration. however, I think the idea of redundancy for the relay is unnecessary. Seriously, how often do relays go bad? I think just keeping a spare relay and hand tools on hand (standard fare for ANY fiero owner) is the way to go. For the time being, I just put in the used sensor which seems to be working fine.
But as these parts become less popular over time we are inevitably going to end up with cheaper auto parts manufacturers taking up the role of filling the demand for the dwindling market. The results are inevitable.
hopefully someone like the Fiero store or other, will pick up the gauntlet.
I found the problem....Yep, a BRAND NEW sending unit and it is crapola. I swapped it out with a unit from a project car I have and BOOM, works like a charm. I knew it could not have been ME!
Anyway, live and learn. Cheap parts are cheap for a reason.
Little did you know thats the best of three usual stickers found, lol
It is worth consideration. however, I think the idea of redundancy for the relay is unnecessary. Seriously, how often do relays go bad? I think just keeping a spare relay and hand tools on hand (standard fare for ANY fiero owner) is the way to go. For the time being, I just put in the used sensor which seems to be working fine.
But as these parts become less popular over time we are inevitably going to end up with cheaper auto parts manufacturers taking up the role of filling the demand for the dwindling market. The results are inevitable.
hopefully someone like the Fiero store or other, will pick up the gauntlet.
Good point. You really don't need two electrical paths to the fuel pump although I use relay redundancy but only to get more current to the pump for a modified 3800SC with greater fuel needs. Replace sensor with one just having the gauge output. Then use the single circuit to drive the fuel pump through the one relay and just carry a spare relay. From the sound of things the new 88 sensors are imported crap and don't work right. The older style "can" sensors" fail if they get wet so the simple solution seems to be the one relay approach.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
