81 Sc no start

[Warren Taylor]

Well guys Katie is sick ... Okay long story short when I turn the key I have power to everything fuel pump is running freq valve is humming but starter won't engage, won't turn over just nothing, I was stranded and tried jumping it off with cables but nothing, I eventually pushed the car in reverse and jumped it off and made it home. But when I was under the hood looking while by buddy turned the key over I noticed the 12V relay closest to the firewall was arching inside, I could literally see the spark, I know this isn't good and possibly my problem, question is can I take one of the relays beside it and plug it in to test it? Thanks in advance

[cwinters01]

I've read the blacks are interchangeable... Just do a quick search on that

[Warren Taylor]

Yeah this one isn't black

[cwinters01]

Bummer. Sounds like poor katie'll just have to be put down then.

[Bob Kontak]

Originally Posted by Warren Taylor

Yeah this one isn't black

cwinters01 knows that. He offered you a viable option. Sparky is the red one, correct?

Your 81 should not have the fuel pump running, nor should the frequency valve be buzzing with the key in the on position.

You have one or a couple of cooties.

Take a black one towards the front and position it in the fuel pump female port.

Turn the key to on.

If no fireworks, walk to the engine bay, remover the air filter cover and air filter. Find the air sensor arm. Lift up on it a half inch. NOW you should hear the frequency valve.

Juice is controlled by a switch on the back of the air sensor assembly. If the arm is not lifted, the relay will not be energized to fire the fuel pump & freq valve.

If frequency valve/FP is buzzing, unprovoked, we have to dig deeper.

If this cures the problem, buy the expensive red one from Pelican. They are like $40.

I know that there is starter interface between the red one and another relay. Next one towards the front I think. I say this loosely as I do not know for sure. A cooked red one may be the culprit?

[Warren Taylor]

None of them are red, one closest to firewall is brown rest are black, are the others 12v as well? And I may be off on terminology but I do hear a humming near the front when key turned assumed it was fuel pump

[boyt911sc]

Originally Posted by Warren Taylor

None of them are red, one closest to firewall is brown rest are black, are the others 12v as well? And I may be off on terminology but I do hear a humming near the front when key turned assumed it was fuel pump

Warren,

Your problem with the starter has no relation to the relays in question. Even if you removed all these relays from the fuse box including the fuel pump relay, the starter should be able to crank the engine when you turned the ignition switch to START position. If the starter failed to crank;
a). Starter solenoid could be defective?
b). No power is getting to the solenoid due to defective ignition switch (?).
c). Poor ground connection.
d). Loose connection at starter terminals.
e). Low battery voltage.
f). Defective starter motor.
g). Others

Tony

[Warren Taylor]

Thanks Tony, where can I start troubleshooting? Already checked the obvious like terminals

[Bob Kontak]

Originally Posted by Warren Taylor

And I may be off on terminology but I do hear a humming near the front when key turned assumed it was fuel pump

OK - "Key Turned" means when you try to crank the motor or when it's just in the on position?

(Let's treat the relay/key on/fuel pump stuff as a secondary) Would be nice to get your engine turning over first.

[theiceman]

sounds like starter solenoid or motor.
If your grounds are tight and probably are if this was sudden.. I would get under and see if you have 12v on the yellow line coming into the starter solenoid when you put the ignition in " start" if you see your 12 volts then it is likely your starter solenoid has failed ( in fact you can lightly tap it to see if it releases and works ). if no 12v go back and investigate your ignition switch .

[Bob Kontak]

Originally Posted by Warren Taylor

Thanks Tony, where can I start troubleshooting? Already checked the obvious like terminals

I would cut to the chase.

Lift car and support. Get under there with a multi meter on DCV and when your friend "starts" the engine, there should be 12V indicated from the yellow ignition wire at the solenoid.

Is this something you can do?

[boyt911sc]

Originally Posted by Warren Taylor

Thanks Tony, where can I start troubleshooting? Already checked the obvious like terminals

Warren,

Bob K. and theiceman have given you good advices for troubleshooting. Instead of a multi-tester I like to use a 12-volt test light. If you are getting 12 volts signal at the starter terminal, ignition switch and 14-pin connections are good. Listen to these guys, they have proven successes in their troubleshooting.

Tony

[Bob Kontak]

Originally Posted by boyt911sc

I like to use a 12-volt test light.

Easier than MM.

Warren, not trying to over simplify but helps if you don't have experience. On the the test light, make sure the alligator clip end is connected to a very good ground. Transmission case maybe? Metal. Tip to yellow wire terminal on solenoid.

Have a friend with very nice Porsches that once asked me if paint would conduct 12V. It won't.

Also, to answer an earlier question, all the round relays are 12V relays.