Johnm
89dualliehauler
Tow cat thought this might be helpful for those of you transplanting a p-pump 12v motor. I learned the hard way that this works great when I transplanted a 96 12v into my 89 d350 dodge. below is my wire up for the relay. you will also need to supply a third low output 12v switched, hot at crank to the third wire on the solinied.
So to be clear, one wire is ground, one is hot at crank and needs to be ran though the relay i describe below. this wire pulls up the plunger and gives you fuel, but should not have current on it for more that a few seconds (as an example while cranking) if it has current too long you will let the smoke out of it. and as we all know electronics work on smoke, if you let it out it quite working
The third is a hold wire , this is the 12v switched, hot during crank. it holds the plunger up but requires very little amperage..it should have current any time you want the engine running. you remove power from this one, the plunger drops and the motor shuts down.
below is the description of how to wire a ford relay to give the high current crank out put for the solenoid. do not use a wire right off the ignition. you will be buying a new ignition switch if you do.
I got pissed off and realized i could simply wire up a cheap ford mustang starter relay in place of the $100 plus one that plugs in. the ford starter relay is 12 bucks at kragen's.
just supply the 12 hot from the original harness (in the case of a transplant battery constant, but this can be over 70 amps, so use a circuit breaker on it) to one of the large posts, the power out to the plunger solenoid to the other and the hot when crank goes to the small terminal on the relay.( you can steal this right off the starter) it does the same thing that the factory one does but can handle a hell of a lot more current. the last wire on the factory plug is just a ground. since the ford relay gets ground through the mounting tabs it is not needed. also watch out, some of these after market relays have 2 small posts. just make sure you use the starter post. to test groud the relay, hit the starter post with 12v and test for continuity between the latger posts. if you have it when you supply 12v you are good. the relay should be open when it has no power on that post as well.
So to be clear, one wire is ground, one is hot at crank and needs to be ran though the relay i describe below. this wire pulls up the plunger and gives you fuel, but should not have current on it for more that a few seconds (as an example while cranking) if it has current too long you will let the smoke out of it. and as we all know electronics work on smoke, if you let it out it quite working
The third is a hold wire , this is the 12v switched, hot during crank. it holds the plunger up but requires very little amperage..it should have current any time you want the engine running. you remove power from this one, the plunger drops and the motor shuts down.below is the description of how to wire a ford relay to give the high current crank out put for the solenoid. do not use a wire right off the ignition. you will be buying a new ignition switch if you do.
I got pissed off and realized i could simply wire up a cheap ford mustang starter relay in place of the $100 plus one that plugs in. the ford starter relay is 12 bucks at kragen's.
just supply the 12 hot from the original harness (in the case of a transplant battery constant, but this can be over 70 amps, so use a circuit breaker on it) to one of the large posts, the power out to the plunger solenoid to the other and the hot when crank goes to the small terminal on the relay.( you can steal this right off the starter) it does the same thing that the factory one does but can handle a hell of a lot more current. the last wire on the factory plug is just a ground. since the ford relay gets ground through the mounting tabs it is not needed. also watch out, some of these after market relays have 2 small posts. just make sure you use the starter post. to test groud the relay, hit the starter post with 12v and test for continuity between the latger posts. if you have it when you supply 12v you are good. the relay should be open when it has no power on that post as well.
