electrical problem with relay

[fartman]

Greetings,

its a 1981 bronco 351w. holley 2bbl carb. msd coil. 8.5mm msd wires, k&n and flowmaster.

OK the problem- no spark but will crank and crank then backfire. So I follow from the batter to the starter relay, from the relay to the module ( new module) and then to the coil. Then I find this relay(not sure what relay it is). So I replace it hoping that was the problem, nope, but with my test light I find one side of relay has power and the other does not. So I jump it with a paperclip and walla, it fires. It runs fine with the paperclip, but even after 3 new relays its not working. Also my tach stopped working if that has anything to do I dont know. I also noticed that my coil has a + and - but the wierd this is the side that has the - has power. This is how it was when I bought it, so I dont know. I don't want to flip them and burn something up so PLEASE anyone help.

Also the relay, once jumped will activate a small sensor in the carb. I pulled it and it has a small metal rod that extends once it gtes power. I pulled that sensor and jumped it and it fired up so the sensor is not the problem.

Thanks guys,

 

[Seabronc]

Welcome to the Zone, post a couple of pictures when you get a chance.

The tac not working may be a further symptom. Check fuse 18, it powers the tac and also, depending on what area of the country this Bronco was originally built for, other various functions like the Throttle Kicker Module, Carborator Vacuum Valve Solinoid, EEC Relay, Throttle position Solenoid, choke heater, seatbelt warning, etc.

Good luck,

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