Blowing Engine Fuse

[Black20FWD]

Here is the problem... My car is turning over and getting no fuel or spark. I noticed that my CEL is not on so I check the fuses. Notice my Engine Fuse (20 amp) is blown. I put a new one in and turn the car to run. The CEL comes on and immediately turns back off. I check the fuse and it has blown again. I then disconnect the alternator, after searching on here to get a clue, and still the same problem. Then I notice that when the MPI relay clicks the fuse blows. Well I take the MPI relay out of the car and now the ECU does not have power. From searching I gather that this is correct as the MPI powers the ECU somehow. SO now I am stuck with trying to search on here to test the relay. Well all these threads are saying ground pin 10. My MPI relay only has 8 pins.HMMMM Now I am stuck with possibly going to buy another relay. If this does not fix the problem then what else could it be. Just looking for suggestions........

 

[munguiaoh]

i had some of those big fuses blow on me a couple of times.

-i had a wrench touch the pos + side of the alt and fuse blew.

-a month after i connected my turbo timer, one of the big fuses blew again and my car wouldent start. i just checked the connections for grounding.

check your connections for anything grounding under the dash.

 

[Old Mitsu Tech]

If it blows the second you turn the key on, you my friend have a dead short. You are going to need an electrical schematic. I would one at a time remove everything that is on that circuit to maybe isolate the problem. You can also get an automatic resetting circuit breaker and install it in the engine fuse holder. Using your test light you can probe each wire associated with the problem. Follow it from the fuse to the point where it ends with each wire. When your light quits flickering you have gone past the point of the short. You need only to back track to the source. Check in areas that lay along and on something metal. Check in areas that may be pinched when tightening a belt etc.

Good Luck

 

[luv2rallye]

This will help in finding a short: http://www.dsmtuners.com/forums/showthread.php?t=179481

 

[Black20FWD]

I figured it was a short. I unplugged the MPI relay and have no power to the ECU and No engine light. Also I can turn the power on with the relay unplugged and the fuse does not blow. So I have it narrowed down to something between the MPI and the Fuse I think. Could it also be that when the MPI clicks it is then shorting out on where the current goes from there? Man I hate electrical stuff. Why cant it be the engine blew. I know how to fix that problem.

 

[steve]

Also I can turn the power on with the relay unplugged and the fuse does not blow. So I have it narrowed down to something between the MPI and the Fuse I think. Could it also be that when the MPI clicks it is then shorting out on where the current goes from there?

Clearly the problem isn't between the MPI relay and the fuse or it would pop with or without the MPI relay installed. Since the problem only happens with the relay installed and after it has activated the problem is after the relay.

That doesn't help much since the MPI relay powers up half the engine bay and the ECU.
You need to get a copy of the MPI circuit diagram for you car. Go through and disconnect all the things that get power from that circuit and see if the fuse pops. If it does you either missed something or the harness is shorted somewhere. If it doesn't blow you go and reconnect things one at a time until you find the part causing the problem.

If you don't have the FSM, now is a great time to get a copy. It will save you countless $ in the future.

Steve

 

[iceman21221]

Did the OP ever resolve this issue?

 

[subie_hunter]

Did you resolve this I am having the same sort of problem.