Engine fuse keeps shorting - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 01-15-2010, 09:45 PM   #1
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default Engine fuse keeps shorting

The 15 amp fuse labeled engine fuse keeps going out on me. I'm able to start the car for about 15 seconds and then it will die. I took out the adaptronic ecu and it still does it. Im kind of clueless where else to look. All the wires that go to the cooling fans look good and so do the wires that go to the back of the coil packs. It use to run fine, so I'm assuming a wire somewhere got either ripped off or melted. Can someone give me some pointers on where to start? And would a bad coil pack cause this? Thanks in advance
ls1motorsports is offline   Reply With Quote
Old 01-15-2010, 10:18 PM   #2
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,362
Total Cats: 1,323
Default

Engine fuse controls the main relay and fuel pump relay. Start there.
Savington is offline   Reply With Quote
Old 01-15-2010, 10:22 PM   #3
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default

Thanks savington. I can hear my fuel pump kicking on and priming when i turn the key. Would a bad fuel pump relay still be able to blow the engine fuse? Also if you could point out where the two relays are in the car, that would be greatly appreciated.
ls1motorsports is offline   Reply With Quote
Old 01-15-2010, 10:32 PM   #4
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,362
Total Cats: 1,323
Default

I don't remember where they are on a stock car, sorry. Mine have been relocated. I think they are up under the dashboard, unfortunately.
Savington is offline   Reply With Quote
Old 01-16-2010, 12:19 AM   #5
Junior Member
iTrader: (1)
 
Join Date: Apr 2007
Location: Toronto, Canada
Posts: 455
Total Cats: 18
Default

Sav is only part right.

The 2000 wiring diagram shows the engine fuse feeding the coil side of the Main Relay - not the switched side (not the fuel pump relay).

The engine fuse also feeds the Ign coils, O2 sensor and airbag module.

Start with the easy stuff - pull the main relay, it's in the engine compartment fuse box. Turn on the ign (the car won't start) see if the fuse blows - if it does the problem is between the fuse and the relay, O2 sensor or airbag module. If it does not blow it's the relay.

With our modded cars my bet is the O2 sensor wire or the sensor itself.
BarbyCar is offline   Reply With Quote
Old 01-16-2010, 02:09 AM   #6
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default

^ so the engine fuse doesn't have anything to do with the fuel pump relay? Ill be taking my exhaust apart soon to check the o2 sensor wires, these wires could possibly have melted because they are right by my down pipe. Also would a bad o2 sensor make the engine fuse pop? I figure it would just make the car run like crap since its not having a good signal to monitor the afr's.
ls1motorsports is offline   Reply With Quote
Old 01-16-2010, 12:19 PM   #7
Junior Member
iTrader: (1)
 
Join Date: Apr 2007
Location: Toronto, Canada
Posts: 455
Total Cats: 18
Default

Quote:
Originally Posted by ls1motorsports View Post
^ so the engine fuse doesn't have anything to do with the fuel pump relay? Ill be taking my exhaust apart soon to check the o2 sensor wires, these wires could possibly have melted because they are right by my down pipe. Also would a bad o2 sensor make the engine fuse pop? I figure it would just make the car run like crap since its not having a good signal to monitor the afr's.
**Disclaimer - I'm using 2000 Wiring Diagrams, your 1999 may vary**

The engine fuse will not blow with a fuel pump relay problem.
The fuel pump relay is fed by the Fuel Inj fuse (30amp)

Does the fuse still blow if you just turn on the ign and don't start her up?

Did you check the Main Relay?

The O2 sensor from the point of view of the engine fuse is just a heating element - if it is contacting the inside of the case when powered - voilą

Could still be the coil pack or airbag module (note the airbag module is in self test when started up) . Try unplugging them both and see if the fuse still blows - add them back one at a time until it blows.

Good luck - at least it's not intermittent so you'll know when it's fixed.

Last edited by BarbyCar; 01-16-2010 at 12:35 PM. Reason: Added Airbag self test comment
BarbyCar is offline   Reply With Quote
Old 01-16-2010, 12:28 PM   #8
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default

yes i see. Thank you very much baby car, for your inputs. Would you be able to tell what else the engine fuse is connected to? I'm not so great at reading wiring diagrams.
ls1motorsports is offline   Reply With Quote
Old 01-16-2010, 04:31 PM   #9
Junior Member
iTrader: (1)
 
Join Date: Apr 2007
Location: Toronto, Canada
Posts: 455
Total Cats: 18
Default

Quote:
Originally Posted by ls1motorsports View Post
yes i see. Thank you very much baby car, for your inputs. Would you be able to tell what else the engine fuse is connected to? I'm not so great at reading wiring diagrams.
Engine Fuse is connected to:

1) Cooling Fan relay coil side (not switched side - not cooling fan itself). Near engine bay fuse box.
2) Main Relay coil side (not switched side)
3) Ignition Coils
4) Oxygen Sensor - front and rear
5) With A/C - Condenser Fan relay coil side (not switched side) behind driver's side headlight
6) Airbag control module under the dash
7) Data Link Connector - Engine bay driver's side
8) With Daytime Running lights - DRL Control Module under the dash

All of these wires on a 2000 are Black/White
BarbyCar is offline   Reply With Quote
Old 01-16-2010, 11:58 PM   #10
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default

wow. thanks for the checklist. I appologize for being kinda blunt on how to check to see if I have a short. So do I just go and check all of the black and white wires connected to these and make sure that one of them isn't hitting a ground? Or what is the proper procedure to taking care of this problem?
ls1motorsports is offline   Reply With Quote
Old 01-17-2010, 11:02 AM   #11
Junior Member
iTrader: (1)
 
Join Date: Apr 2007
Location: Toronto, Canada
Posts: 455
Total Cats: 18
Red face

Step 1 - Does the fuse blow with the ign on but engine not running?

a) If Yes - Disconnect everything on the list and try again.
Does the fuse still blow with ign on? If Yes, you have eliminated all the components as the problem - but not the wiring up to them - start tracing wires for a short. If No, start reconnecting one at a time until the fuse blows.

b) If No - Disconnect everything on the list that is not required to run the engine and start the engine.
Does the fuse still blow? If Yes, you have eliminated all the components that are now disconnected, start tracing the wires to the still connected items. If No, start reconnecting one at a time until the fuse blows.
BarbyCar is offline   Reply With Quote
Old 01-17-2010, 12:28 PM   #12
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2009
Location: illinois
Posts: 190
Total Cats: -4
Default

WOW greatly appreciated barbycar!
ls1motorsports is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Need help - Stock Balancer and Fastforward overlay pulleys Frank_and_Beans Supercharger Discussion 13 09-12-2016 09:17 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:28 AM.