Engine fuse keeps blowing

[bboypuertoroc]

aiight PLEASE GOD I NEED HELP. I've had my car at TWO shops now and they can't figure out the problem. My engine fuse (20 amp) keeps blowing for no apparent reason. First time it happened I swapped in a 30 amp fuse. That one blew too. Took it to a shop and after a couple days they couldn't figure out the problem. They let the car run for hours on end but the fuse was fine so they thought they fixed it by just putting a new fuse in. That on blew. So i took it to another shop and they found that my tranny bracket was broken and the tranny mount rubber insert was ripped in half. So they thought that when the engine rocked during shifting (and did it ever, like 6-10 inchs out of place) it was pinching a wire somewhere and shorting it. No, thats not the problem. It's still blowing. So beefore I return as much of my car to stock as possible so I can take it to Mitsubishi, I'm wondering if anyone has ever had this problem and if any electrician magicians out there might now the problem/fix. It seems to happen when i shift at higher RPMs (somewhere above 4k). It won't cut off at the higher RPM but once it drops back down within a couple of minutes the car just dies. Everything works (lights, radio ect.) and the car turns over but it doesn't actually start. I don't know what runs to that fuse but the car needs that fuse to move. Sorry I made this a novel but I'm trying to explain this as best i can. I appreciate help from anyone. Peace.

 

[Maxximillion]

check the MPI relay, it provides power to the ECU, fuel injectors, and the fuel pump, the fuse that keeps blowing on you is on the wire that provides the MPI relay with power to control these things. without it, your car wont start but it will keep turning over. like you said it does. the relay might have developed a short or it could be something up the line from the relay. if you want the procedure on how to check the relay let me know but the procedure is all in the chilton or haynes book. you do have a chilton or haynes book don't you?

 

[bboypuertoroc]

Yeah, I got the Haynes book. Aiight bet I'll check that out then. Do you know what could have caused it though? The most recent mod I did was my Apexi N1 DP. The stock dp/cat had something that looked like a ground or something connecting from the cat to the bottom of the car. I don't know if the 1g's got that but the 2g's do. I doubt it had anything to do with that but who knows. Aiight man thanks for the help and I'll update when fixed. Peace.

 

[NeEmO6]

I had the same problem not that long ago. Tuned out my aftermaket alarm that was causing the problem, undid it and no more blown engine fuse. Something to look into.

 

[bboypuertoroc]

Oh yeah I lied... the problem doesn't just happen after high RPM shifts, cause I just blew another fuse on my way home for lunch going no higher than 3k RPM. It seems I get about 30 minutes of total driving time (not all at once) before each fuse blows.

 

[bboypuertoroc]

Do you think that would be the same with the stock "alarm"?

 

[Maxximillion]

judging from my experiences with the DSM (and there have been many) i wouldn't put my money on it being the stock alarm doing anything wrong. the reason why i suggested the problem lying in an aftermarket install of an alarm or remote starter is that its a tricky job in the first place, especially if your not sure what your really doing. if someone does a cut and hack job at an install, doesn't make sure to insulate connections properly, then there are going to be problems. but if your all stock there i'd be looking somewhere else.

maybe sterio install? if its not stock i'd be looking at the quality of install, like did you or they use shrink tubing or tape? did they solder connections or twist and tape, did they use crimp connections and if so are they done properly. but i also doubt that would be it.

you say that you get about half hours driving time, well to me that sounds more like something is shorting or something triggers a short. i doubt it would be from any of your accessories. unless they are using the MPI's power source but i also doubt that. umm the best thing to do is narrow the things it could be down. but first go into your chilton or haynes book and in the fuel/exhuast systems chapter find the fuel pump section and go through the steps it says to check your MPI relay. your relay is located on the right side of your centre consol, underneath and to the right of your sterio, take off the right side carpet panel of the centre consol and you will see to golden screws lined up vertically about an inch apart, take those out and pull out the little golden box and unclip it. congratulations you have your MPI relay. the fuse that keeps blowing on you powers that little box. now you have to figure out why.

is there something interupting or drawing current betweent the relay and the fuse on the batter post?, is there a short in the relay itself? (you check this by following the procedure in the book listed in the fuel pump section of the fuel/exhaust chapter) or is the short comming from the key ignition point? hence why i asked about the remote starter because thats where wires are cut and crimped and mistakes easily made. do you hear clicking noises coming from behind the centre consol while driving? or do you smell anything like bad fish? thats a sign that the caps in you ECU are leaking and corroding the ignition setup on the circuit board.

at this point you have to answer those questions and get back to me. but i'd be willing to put my money on either the relay, the ignition switch or the ECU at this point.

one more thing. could be related or not. a couple years ago i had a talon that whenever i floored it and let off my car would power off and then on again. like it would be like i took the key out of the ignition completely or something. i later discovered that when i had brought my car to a battery store and had them put in a 1200 watt cranking battery, they had put the battery on top of a set of wires. i think they were the main power wires for the car and eventually it ate through the shielding of the wires and started shorting to the metal bracket. i had them replace everything t'was a good day. but check that out too. look to see if there are any trapped wires under the battery. let me know how it goes.

Jason.

 

[99redgst]

Check out the alternator, very common for it to blow the engine fuse when it shorts out. It happened to me, had me stumped for a couple days. Although my fuse would blow as soon as I tried to move the car. If it is blowing fuses very fequntly try unpluging the connector from the alternator and drive around or take the alternator to autozone or some place that can test them.

 

[bboypuertoroc]

Aiight well I HAD a Haynes book but that's in my wifes 3000 GT which was murdered... me and her got in a car wreck... better yet ran off the road by some b!tch in a white suburban who didnt even have the common decency to stop and see if we were alright. But yeah yo Maxximillion if you can hook me up with that procedure to check the relay or if they got the Haynes manual online or something cuz I need to fix my car ASAP cuz its all i got to get around in now. Thanks man

RIP 3000 GT

 

[Maxximillion]

hey man sorry to hear about the 3000GT, did you ever get insurance money back from it? did that bi*** ever get caught by police? anyway yeah i'll type out the procedure for you. did you get the relay out?

the first thing you need to do is test for power to the relay on the 10th pin on the harness itself. looking at the harness in the car, and with the clip of the harness facing the top, the 10th pin is located at the bottom left corner of the harness. test for 12 volts (with a new fuse in of course) it should be constant.

__________|```|__________
/ 1 2 3 4 5 \ (there is no pin number 1)
| | this sorta looks like the
| 6 7 8 9 10 | pin setup on the relay.
|_________________________|


1. first test - install jumper wires from terminal number 10 on the relay to the positive terminal of the battery and terminal 8 to the negative terminal or to ground. with the relay energized (and you should hear an audible click noise) connect the negative probe of a volt meter to the battery ground. and then with the positive probe, connect it to terminal number 4 and then 5 on the relay. you should be seeing 12 volts on both terminals.

2. test two - connect the jumper leads from terminal number 9 to the battery positive terminal and terminal 6 to the battery negative terminal. check for continuity between terminals 3 and 2 there should be continuity. now remove the ground lead from terminal number 6 on the relay. the ohmmeter should now indicate no continuity.

3 test three - install jumper leads from terminal 3 to the battery positive and terminal 7 to the negative. check for voltage with the positive probe on terminal 2 and the negative probe on the battery ground. there should be 12 volts. remove the ground lead from terminal number 7 and the voltmeter should indicate zero voltage.

if any of these tests fail then replace the relay, if all tests passed then its something else. heres a web site with a schematic for the wiring of our cars. it might be a little hard to read but study it and you should be able to figure some other things out. if you have any more questions or theories you'd like to voice i'm all ears.

Jason.

 

[BluemeanieTSi]

fuses blow because of direct shorts or too much power draw not because of bad relays not sending power. usually they blow from shorts on the cam/crank sensor wires

 

[BluemeanieTSi]

Check out the alternator, very common for it to blow the engine fuse when it shorts out. It happened to me, had me stumped for a couple days. Although my fuse would blow as soon as I tried to move the car. If it is blowing fuses very fequntly try unpluging the connector from the alternator and drive around or take the alternator to autozone or some place that can test them.

alt shorting out blows the alt fuse not the engine fuse

 

[Batmobile]

does it idle fine?
Cause my 420a motor..had this problem..but it was worse..it would blow that fuse..and then blow my ecu....ya..not fun...finally I found out it was caused when I had rebuilt the motor.>I was rebuilding 2 420a's at the time..and I had drop one of the intake manifold....well it was the one I put on my car...and I did't notice no cracks or nuff'n..well over the time it built an inner crack...and was causeing my car to idle at 1500-2000 sometimes NOT stop climbing rpms till you turn the car off..but I'm SURE this isn't what your dealing with.

 

[BluemeanieTSi]

does it idle fine?
Cause my 420a motor..had this problem..but it was worse..it would blow that fuse..and then blow my ecu....ya..not fun...finally I found out it was caused when I had rebuilt the motor.>I was rebuilding 2 420a's at the time..and I had drop one of the intake manifold....well it was the one I put on my car...and I did't notice no cracks or nuff'n..well over the time it built an inner crack...and was causeing my car to idle at 1500-2000 sometimes NOT stop climbing rpms till you turn the car off..but I'm SURE this isn't what your dealing with.

um...when that fuse is blown you odn't get spark/fuel

 

[bboypuertoroc]

Thanks for the help Jason... I'ma do that as soon as I get off of work. Yeah I'm getting $5419 for the 3000GT... that's like 2 g's more than it's worth. Cops never got the bi*** though... they didnt even try. Probably didn't help that my wifes license plate said "GRL RASR" either. Oh well, that's EVO money now. I'll let you know tomorrow or the next day how everything goes. Peace

 

[bboypuertoroc]

Yeah but will the cam/crank sensor wires cause the engine fuse to blow?

 

[BluemeanieTSi]

Yeah but will the cam/crank sensor wires cause the engine fuse to blow?

if there is a short - yes

 

[Maxximillion]

my stupid picture didn't work here it is.......this is a representation of what the pins on the relay are and the web site is www.taboospeedshop.com/wiring.htm good luck.

_________|````|__________
/ 1 2 3 4 5 \
| 6 7 8 9 10 |
|_________________________|

note: on the relay you will notice there won't actually be a number one pin

 

[gsxgota]

i have the same problem right now, i was driving and the car decided to die on me. my engine fuse is blown too, and keeps blowing, i had a new alarm installed a few days before it happend, its a remote start, but they did not hook that part, up, because they didnt want to be liable for anything, so i planed to do that my slef. im still trying to figure out whats wrong, i just ordered a new relay, so im going to see if that works.

 

[Maxximillion]

crap my picture changes format once i send it. but on the relay with the clip facing the top the pins are 12345
678910

 

[misterfutureboy]

Like 3 or 4 months ago, my engine fuse also blew out numerous amounts of times. Turned out to be a faulty alternator.

 

[Maxximillion]

hey, if it was a faulty alternator, wouldn't the alt fuse blow and not the MPI relay fuse? just doesn't make sense to me. not trying to start crap but i would like to gain more info on how the electronics work on our cars. any supporting information to back it up?

Jason.

 

[bboypuertoroc]

Aiight so my relay and ECU are good... what else is left? I'm guessing just the line from the relay to the fuse. I'll check out the alt thing too but the only prob with that is my alt is only about 10,000 miles old (maybe less). But I'll still check. I dropped in a 40 amp fuse yesterday morning and it seems to be holding its own right now... if not I'ma step it up to a 50 then a 60. HOPEFULLY that won't need to happen cuz the problem should be solved by then. Well it's back to work. Peace

 

[bboypuertoroc]

I'll also check out the cam/crank sensor thing that bluemeanieTSI was talking bout.

 

[99redgst]

hey, if it was a faulty alternator, wouldn't the alt fuse blow and not the MPI relay fuse? just doesn't make sense to me. not trying to start crap but i would like to gain more info on how the electronics work on our cars. any supporting information to back it up?

Jason.

When my alternator shorted out it blew the engine fuse. I descibed the problem to a tech after looking at wiring diagrams and going crazy, without even looking at the car he said it was the alternator. I really didn't believe him, he came and looked at the car and unplug the alternator and it ran fine. I have seen this happen to other people on the forum as well.

As far as putting in higher amp fuses, that is about the worst idea ever. It is blowing because you have a problem, fix it. Sure the fuse might not blow but instead a wire will burn up or something worse. The circuit was only designed to handle that many amps, putting in a higher amp fuse is just a band aid that is going to cause greater problems.