Fuel pump power issue 86 MR2 - Toyota Nation Forum : Toyota Car and Truck Forums

Crash Johnson · 05-18-2011, 10:28 AM

So, 86 NA 1.6 Mr2 has been sitting a while, started every now and then but probably not enough. ill cut straight to the problem. Fuel pump will not run after startup. at keyon it will cycle and turn off, obviously it has power and works. jumpered out the fuel pump on the diag port and the car runs fine. replaced the MAF with one from a 22r I had laying around (oddly enough the same MAF) still same issue, replaced the relay with same relay from same 22r truck. still no go. held the flap open on original MAF and it still would not power the fuel pump. is there something I'm missing that could cause this? I cant find where the pump gets power from while the engine is running so I cant trace the wire back and check voltage. about to just wire the pump to a switch on the dash at this point.

Thanks for any info.

toyotaspeed90 · 05-18-2011, 03:34 PM

when the AFM is open it triggers the circuit opening relay to turn on.... there's also a fuel pump relay

so if it's none of those, then it's wiring somewhere.

Crash Johnson · 05-19-2011, 07:58 AM

From what I gather the Circuit opening Relay and the Fuel pump relay are actually inside the same relay on the 86 mr2 can anyone confirm that?

Thanks

Crash Johnson · 05-19-2011, 09:54 AM

Little help from RU2CHKN in another post http://opc.mr2oc.com/online_parts_ca...mpartment1.gif
shows it being in the same relay and apparently its a solid blue wire that runs to the fuel pump. I know at the fuel pump end there are 2 blue wires, at least now I know which one is the run power wire and which is the start power wire. also its a green-red wire going to the MAF that if working properly would be grounded (brown wire out of MAF to ground) while the maf is open. I'll look at it this weekend or maybe tonight if I get a chance.

Thanks