cocheeze Posted July 16, 2008 Share Posted July 16, 2008 i got reffered here from the nasioc forums because the word on the street is there are some electrical gurus over here... my 1986 Subaru GL Wagon (no ac or power steering, manual tranny, 4wd) keeps blowing the meter/engine fuse in the fuse panel. I have replaced it with a 15A (the rating it takes), 20A and 25A fuse, and every time it blows again within a few seconds of starting the car. the really wierd thing is that the car dies when the fuse blows, which seems strange to me considering that the instrument cluster isn't really connected to the ignition as far as i know. also, no other fuses are blown or missing, the fusible links are fine, and i have unhooked/removed the instrument cluster and the fuse still blows, which would suggest a fault in the wiring, however the wiring all looks brand new - like it just rolled off of the assembally line. i can't read the oil pressure, tach, water temp, voltage, or fuel gauges until i fix this problem, and i have to keep driving the car for my job, so any help i can get asap would be really really appreciated! thanks! Link to comment Share on other sites More sharing options...
The Scooby Posted July 16, 2008 Share Posted July 16, 2008 you have a short somewhere in the wiring that is causing it, look for arching at night time in the engine bay with someone helping. Link to comment Share on other sites More sharing options...
McDave Posted July 17, 2008 Share Posted July 17, 2008 I posted this in another thread awhile back... Finding shorts 101: Go to the parts store and get a circuit breaker (CB) in the same size as the fuse the dash lights are supposed to use. Also get a couple feet of wire and some wire terminals so you can attach the wires to the CB and plug the other ends of the wires into where the fuse belongs. Before plugging in the CB, make a note of everything that doesn't work besides just the dash lights. Don't forget to check the cigarette lighter too. Now plug in the CB and when you turn the key and lights on, the CB will start tripping off and on instead of burning up fuses. Start disconnecting everything that wasn't working before with the blown fuse. Once you unplug the offending item or circuit, the CB will stop tripping and you have now isolated the culprit. For instance, if the cigarette lighter was one of the items that didn't work with the blown fuse, start with it since they often short out. Or, if you unplug the dash and it quits tripping the CB, the problem is with the dash cluster. Continue unplugging stuff that didn't work until the CB stops tripping. Once the CB stops tripping, repair the short or replace the offending item. After repairs are made and the CB stays on, you can go ahead and plug everything else back in. As long as the CB doesn't trip again, you can go ahead and put a new fuse in. Done! Edit: As Gloyale noted below, you may not be able to *notice* everything that's not working, such as the choke and bowl vent solenoid. I should have stated one you reach the end of the *noted* non-working items like the lighter and/or dash lights, continue unplugging other items, like the carb connector until the CB stops tripping. Once you reach that point you may have to plug the connector back in and unplug individual items, like the choke or bowl vent to further isolate the offending part/wiring. Sooner or later you will unplug the offending circuit. You just may have to do a bit more detective work to get down to the actual bad part/wiring. Link to comment Share on other sites More sharing options...
Gloyale Posted July 17, 2008 Share Posted July 17, 2008 I'll bet the heating element in the auto choke mechanism has shorted. Or possibly the bowl vent solenoid. Both are located on the carb, and they are powered when the ignition is on by that fuse. Try uplugging one at a time and installing a new fuse to see if it blows. Link to comment Share on other sites More sharing options...
Cougar Posted July 17, 2008 Share Posted July 17, 2008 The fuse may feed power to the ECU also or possibly the MAF. The problem is most likely under the hood but it could be elsewhere. I do not have my data reference to look at right now. Is the circuit having trouble on fuse #12? Link to comment Share on other sites More sharing options...
Gloyale Posted July 17, 2008 Share Posted July 17, 2008 The fuse may feed power to the ECU also or possibly the MAF. The problem is most likely under the hood but it could be elsewhere. I do not have my data reference to look at right now. Is the circuit having trouble on fuse #12? His 86 4wd is Carbed. Meter/engine fuse IIRC is fuse 5. Before plugging in the CB, make a note of everything that doesn't work besides just the dash lights. Don't forget to check the cigarette lighter too. Problem is in this case you won't *notice* all the things that aren't working because there is no way to *see* whether the choke has power. You need to check with a meter or test light. You need to disconnect the bowl vent solenoid and the auto choke wires. Then see if it still blows. *NOTE* if you disconnect the main connector on the carb, the anti-diesel solenoid won't get power. So you have to remove the wire off the choke and bowl vent solenoid seperately. Link to comment Share on other sites More sharing options...
McDave Posted July 17, 2008 Share Posted July 17, 2008 Before plugging in the CB, make a note of everything that doesn't work besides just the dash lights. Don't forget to check the cigarette lighter too. Problem is in this case you won't *notice* all the things that aren't working because there is no way to *see* whether the choke has power. You need to check with a meter or test light. You need to disconnect the bowl vent solenoid and the auto choke wires. Then see if it still blows. *NOTE* if you disconnect the main connector on the carb, the anti-diesel solenoid won't get power. So you have to remove the wire off the choke and bowl vent solenoid seperately. True. I went back and edited the post to address this. Thanks for the heads up. Link to comment Share on other sites More sharing options...
Cougar Posted July 17, 2008 Share Posted July 17, 2008 His 86 4wd is Carbed. Meter/engine fuse IIRC is fuse 5. Thanks for the notice Gloyale. I'll bet you're correct about where the shorted area is. Link to comment Share on other sites More sharing options...
cocheeze Posted July 22, 2008 Author Share Posted July 22, 2008 no wonder they referred me over here from the nasioc board! you guys are crazy knowledgeable! gloyale was right, it was one of the connectors on the carb. i can't figure out which one it is from my manual or by looking at the carb itself, but i unplugged the connector with one green wire and two black with white striped wires that appears to go to multiple areas on the carb and now it doesn't blow fuses anymore. i plan on converting to a weber 32/36 in a few days, but first i have to pass DEQ, and portland has really strict DEQ stations, so i was curious, would it be more likely to pass emissions testing with the plug i unplugged connected or disconnected? thanks again for the help, you guys rule! casey Link to comment Share on other sites More sharing options...
88RxTuner Posted July 22, 2008 Share Posted July 22, 2008 Well, you wont pass ANY emission testing with the electronic controls to your carburetor disconnected. You need to isolate which of the three wires are shorted out. It should be visibly obvious where the wires go, one should go to your bowl vent on the top of the carb, one should go to a metering solenoid (Gloyale, correct me if I'm wrong, you're smarter than me) and the choke should have a separate wire. if any of them are shorted to ground, you will have no resistance between that wire and the body of the carburetor.. and this will blow fuses... do you have a multimeter? If you can isolate which component is shorted out, or if you find a visible short in the wires on the carb (rubbed through and touching the body of the carb), you can fix this! Good luck! 88rxtuner Link to comment Share on other sites More sharing options...
Gloyale Posted July 22, 2008 Share Posted July 22, 2008 You'll get terrible milage and run very rich like that. You can eliminate items one by one. First, disconnect the wire that goes to the auto choke. It is held by a screw and ring connector, so just unscrew it and tape it and set it aside. Put in a fuse and see if it blows. If it still does, you're problem is one of the other 2 devices, The bowl vent solenoid, and the anti diesel solenoid. To test them you can make some jumper wires. Get a few sections of wire, and some male and female spade connectors. make sections of wire with a male on one end, and female on the other. Now you to test the components, use 3 of you're jumpers. Connect them between the harness and the plug on the carb. This will allow you to disconnect each cmponet one at a time, leaving the others hooked up. My money is on the Bowl vent solenoid (drivers side of Carb, upper front) When you unplug that connector entirely, Does it even run? I would think you need to have power to the antidiesel solenoid. (passenger side of carb) If it is running without power to the anti diesel solenoid, it may be stuck *open* and could be you're short. Link to comment Share on other sites More sharing options...
cocheeze Posted July 22, 2008 Author Share Posted July 22, 2008 one more piece of information that might help determine the cause: i noticed that the carb. starts smoking in the couple of seconds before the fuse blows after i turn on the accessory switch. and yes, it runs fine with the connector unplugged. thanks! casey Link to comment Share on other sites More sharing options...
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