on the harness for the fuel injectors on a 88 350 TPI, on the 2 wire connector, shouldnt one of those wires be a ground? with the key on, both wires on the connector light up my test light. my car has had problems running. it gets pressure to the rail but will not run. i dont have a noid light to see if the injectors are working. i was just confused why both wires were hot on th connector, unless i have a ground wire off/broke

 

Injectors are supplied by 12Volts on one pin and the other pin goes to the ECM. It is the ECM that provides the ground signal to complete the circuit and open the injectors.

When testing one injector clip with the other injectors connected, the parallel resistance of the other injectors and lack of ground signal will produce 12Volts on both pins relative to ground. As both pins are 12Volts, the voltage difference across the injectors 2 pins is 0Volts, hence the injector won't open. It's only when the ECM triggers the injectectors to open, that the ECM provides an earth signal pulling down the ECM side of the injector to earth creating 12Volts across the injector causing it to open.

By all rights, if you disconnect all of the injector connections, you should only get 12Volts on 1 pin. The other is open circuit and will be floating with no voltage.

Check this out for some hints.
http://www.hotrodlane.cc/ONLINETECH/TPIwontstart.html

And a noid light would make it much easier to check as you they would flash as the injectors are signaled to open.

Cheers,
Col.

P.S. I think I just might make a budget check light for the injectors. I'll post some details on that later.

 

thanks i appreciate it. i also ohmed my injectors and every single one is at 16 ohms. so i geuss im putting injectors in it seeing as they all tested out of specs which the book said 14omhs. the car has been sitting for about 5-6 years so im not supprised that they turned out bad

 

I would not say your injectors are bad. 305 and 350 Bosch injectors are 16ohm and as they all measure the same, I'd say that they are OK.

It might be worth while getting them cleaned though as fuel does gum up because of the additives that remain when the fuel evaporates. That would also go for the rest of the fuel system too.

 

thats the only thing i havent replaced in the fuel system. my buddy has a set of injectors hes givng me, that im gonna put in this weekend. if this doesnt get the car running, im gonna go ape s@#% lol.