brown/white inline fuse?

[radionovember]

i've been having problems with my lights now working since i've gotten this car. turn signals weren't working so i cleaned up my grounds under the hood and in the trunk, as well as the bulbs holders in the tail lights. signals started working again but off and on. had an alarm system put in and the signals got more intermittent as well as the front left side marker and turn signal going out totally. i got in there tonight to look around and found that the turn signal switch had been unplugged a bit when they wired things back up but i also noticed that the in-line fuse on the brown/white wire was burnt (the white fuse holder was literally burnt). pulled the fuse which came out in pieces and replaced it with a 16 like the one that came out. cranked the car and suddenly when i turned the key out, it stayed running, unplugged the fuse and it finally turned off. thing is, now it wont crank at all. it's behaving like a dead battery. i have power when i turn the ignition key, but it just clicks on crank and goes dead. wont start. the battery tested 12 so i'm thinking my batteries good. i didnt unplug anything or change any wiring so i'm not sure what happened. i'm honestly not super skilled in this but i'm trying to figure it out as i go. does any one have any idea what might have happened? should i just be taking this thing to a shop rather than trying to do it myself. thanks for the help guys...

[digitech]

Not clear from your post - did you re-install the fuse and it still wouldn't start?

[radionovember]

oh, yeah... sorry. now that i read it back, that post wasnt very clear or well written.

i did both with the fuse. I'm not really sure what the brown with white stripe wire does, (in the fuel injection wiring diagram that wire goes to the power distribution connector and on to the "power to starter solenoid" and "power to starter motor"). but here's whats happening: it's been cranking, even with that fuse burned out.

when i did put the fuse in and cranked the car, i could take the key out and it wouldnt turn off.
then i put the key back in crank position, take the fuse out and it turns off normally.

suddenly, it wouldnt crank though, like a weak battery. i put the fuse back in and no difference so i took it back out.

this morning, i went out and it cranked up like normal (no fuse) but after turning it off and re-cranking, it was a little more dead, and then by the third try, back to like last night. I tried putting the fuse back in but no difference. it almost seams like the brown wire with the white stripe (fuse or no fuse) doesnt affect the car at all.

last thing to note, i just replaced the spark plug wires a day or two ago. the distributor cap had some rust in it and i did my best to clean all that out. i would've replaced it but i have to wait for the part. is it possible that would have any effect?

[james124]

To begin with, you should recharge your battery and see if you get sufficient cranking power. Battery should be at least 12.5 volts.

[radionovember]

ok, i recharged my battery and replaced the negative battery cable and it cranked up but it did struggle a bit. the first time it wouldnt start but the second crank worked with the idle sitting at around 2 rpms about to die. the longer i left it on, it gradually climbed up to around 10 rpms.

i tried that replacing that fuse again and when i turn the car off, all the lights go out but the engine continues to run. i'm just leaving that fuse off the brown/white stripe wire for now but it makes me nervous to leave something just broken. does anyone here have any ideas as to why this fused wire would make my car stay running without the key? think i'm ok without it?

[rlux4]

You don't say what year your car is, but you have said you've looked at the FI wiring diagram, so I'll try to help from there.
If the brown wire with a white stripe wire is up behind the main fuse panel it's for the FI system. When you turn the key on it energizes one side of the dual relay. Then, when the car is cranking, another signal from the AFM makes the contact in the dual relay to turn on the fuel pump. Incoming air through the AFM opens a flap that is connected to a switch, so you could do this by hand by moving the arm on the potentiometer under the black plastic cap. The wire in question should have nothing to do with the ignition/spark circuits. It's part of the safety feature that stops the fuel pump if the engine isn't turning, as in an accident. If it's affecting the car running with the key off your wiring has been altered. You can check if the wire's been altered by checking continuity between the fused end and the other end where it attaches to the dual relay. If the wire's been cobbed by being used to power something else when the key is on, then no doubt they also supplied the fuel pump with another source of 12V that is switched by the ignition switch.
Ron

[radionovember]

dang, you're right... sorry about that. its an 82 spider 2000 so yeah, it's fuel injected. thanks for the info rlux4. honestly, as much as i should probably just know this stuff, i dont. i have only done the normal home mech stuff like brakes, alternator, starter, oil, etc. this helps me to kinda get it.

ill trace that wire down here as soon as i can get back out there.
so then, in summary: my car wouldn't start if the duel relay wasn't getting power from the two sources, one being the AFM? which means, both have to work for the car to be running so i should still be safe with that whole "cut off the fuel in an accident thing"? there's a hum when i turn the key back near my drivers side rear wheel well, i'm guessing that's the fuel pump turning on?

[rlux4]

Probably. It's very common to find the wiring through the dual relay bypassed. Power would be supplied to the fuel pump through some other source that is energized when the key is turned on. This is usually because the setup wasn't understood and when a problem came up, such as a blown fuse on the brown with white wire, it isn't diagnosed and bypassed instead of fixed.
Your summation would be correct if the wiring were still as they should be. Yours is not or you wouldn't hear the fuel pump running when you turn on the key. And the car absolutely would not start if the fuse weren't good on the line. It would crank, and you'd have spark, but it wouldn't get any fuel.
The dual relay needs the signal from both places: ignition "on" and flap in AFM open in order to send the 12V to the fuel pump through the green with black stripe wire coming out of the dual relay.
Ron

[radionovember]

got it! thank you, Ron. i appreciate you take time to explain that too me more than you know. have a great weekend, ok...