Voltage drop in crank

[plumkrazee70]

I have rewired my car with an EZ wire kit and have added MSD ignition along with FItech EFI.

Now I wired the car per EZ wire instructions, which gives me 12V on their "coil wire" in RUN and CRANK which I used to feed my MSD and FItech.

The car will fire and then die when using the key. However, if I put the key in RUN and jump the starter relay, it fires.

This tells me I have to big of a voltage drop on the 12V coil wire when using the ignition switch. I haven't put a meter on that wire while cranking, to see what the voltage is, because I need a helper.

What can I do to solve this? I thought about adding a relay into the 12V coil wire or wiring in a push button start (last resort)

Thanks for y'all help.

 

[plumkrazee70]

Here is how I am thinking of wiring the relay. Will this work?

 

[teringer]

use a relay with a diode in it or it can feed back when on.

 

[67Dart273]

The FIRST thing to do is actually check the voltage. There are only two wires, easily traced, and you need to examine the load you have on it all You don't need a second person you need these wonderful inventions called alligator clips LOL

1....Even with stock wiring, I recommend you add several relays. This depends on the loads on the ignition feed, and maybe even accessory feed. So 1 for high beams, 1 for low beams, and at least one triggered by "ignition run" to feed underhood loads.

2...There is no need for any diode. Jumper the IGN1 and IGN2 together and use that pair to trigger the underhood relay. Feed the power in to the relay from a nice large say, no10 and a big fuse or breaker. If you still have the factory starter relay "the big stud" is a good place.

 

[plumkrazee70]

The FIRST thing to do is actually check the voltage. There are only two wires, easily traced, and you need to examine the load you have on it all You don't need a second person you need these wonderful inventions called alligator clips LOL

1....Even with stock wiring, I recommend you add several relays. This depends on the loads on the ignition feed, and maybe even accessory feed. So 1 for high beams, 1 for low beams, and at least one triggered by "ignition run" to feed underhood loads.

2...There is no need for any diode. Jumper the IGN1 and IGN2 together and use that pair to trigger the underhood relay. Feed the power in to the relay from a nice large say, no10 and a big fuse or breaker. If you still have the factory starter relay "the big stud" is a good place.

Your right. Lol. I have ign 1 and ign 2 jumped together now. I'll check that voltage while cranking today.

I have relays already on the high and low beams and my fuel pump.

Is my drawing above correct for how to wire a relay for the ign?

 

[plumkrazee70]

Ok @67Dart273 Here are the tests I did:

Battery voltage :
Key On Engine Off: 12.51v
Key off Engine off: 12.66v

Voltage at ign 1 + ign 2:
Key off Engine Off: 0.27v
Key on Engine off: 12.61v
While cranking with key, with coil wire removed: 10.89v

 

[67Dart273]

Ok @67Dart273 Here are the tests I did:


While cranking with key, with coil wire removed: 10.89v

OK only other thing you need is what is the BATTERY voltage when cranking?

Or hook your meter to the same place above, and instead of ground, to battery plus. Crank and read. This will give you the voltage drop in that circuit.

if it won't start/ run with 10.89 I'm quickly out of ideas. You might try the test several times, maybe there's an intermittent in the IGN2 circuit

If you want give me a call. Send a PM I'll give you my no.

 

[plumkrazee70]

OK only other thing you need is what is the BATTERY voltage when cranking?

Or hook your meter to the same place above, and instead of ground, to battery plus. Crank and read. This will give you the voltage drop in that circuit.

if it won't start/ run with 10.89 I'm quickly out of ideas. You might try the test several times, maybe there's an intermittent in the IGN2 circuit

If you want give me a call. Send a PM I'll give you my no.

So I was showing my father in law and it wouldn't fire with jumping the relay at first. It took a few tries . So I think with all the key on and off (with out start) it flooded.

I am going to disable the prime shot and run the test a few more times as well as the battery positive to 12v run circuit and check the drop there.

Thanks, Del. If I get stuck I'll PM you.