Does my 1979 Toyota 20R engine have a mech or elec fuel pump ?
3 Answers
if your truck came with FACTORY air conditioning it has an electric pump in the tank. Yes even on a carbureted engine. the a/c compressor went right over the place that the mechanical fuel pump WOULD have gone so Toyota just put one in the tank on these models. power to the pump comes from a relay located to the right side and slightly above the stearing columb. power for the relay and fuel pump comes from the 15 amp ENGINE fuse(Second row from left and 3rd fuse down in fuse block located under dash) make SURE this fuse is good and that the fuse connection points in the block are clean and allowing full 12 volts to pass through it. The black with red tracer at the cut out relay plug is the power out spot to the fuel pump. this black with red tracer wire may not have 12 volts on it when key is in RUN position, because the power applied to the relay in this configuration goes through a resistor located on the right inner fender liner under the hood. ive never been able to find out what the voltage should be to the pump in the RUN position through this resistor. the power goes through this resistor ONLY in the RUN position of the ignition switch. only when you are STARTING/CRANKING the engine dose power get switched to a full (no resistor in circuit) 12 volt power source from the Cranking/STARTING contact points from the ignition switch. THis is a problem I have because I have removed the factory fuel pump from inside the tank and installed an after market type pump at the tank and am trying to feed it with the factory wiring (Black/red wire). I get about 9.4 volts there when key is on in run position because it is getting power through the resistor under the hood. My next move is to wire around this resitor and see if I get full 12 volt power to the new pump. Also don't try to just install an outside pump without removing the original in the tank. I don't think the new one can suck fuel through the old one and supply the engine with enough fuel und e all if any conditions. Long winded I know but ive been frustrated with bad and or incomplete info on this subject, and don't want to add to any confusion. That's what I know so far, good luck to all of you working with this problem.DrBob762 out.
