Blew the main fuse...

Max777 · 11-18-2009, 02:11 AM

Today, i did a decent burnout in the rain, (to show my friend the LSD) and the car just completely died in the middle of the street. I looked around and figured out the main fuse got blown.

The fuse was 80amp, I put in a 100amp from s5, and drove it back home, but I'm afraid to drive it now. What do you think could have caused it to blow out?

EDIT: I have had problems with the engine cutting out randomly while daily driving, and very noticeably during a drift practice session. I would start drifting circles, and the car would just "shut down", almost like a fuel cut....

I have an FCD, and my tank was full every time, so I dont think it's fuel or baffles. I think it is electrical, I had a no start, wiggled the wires and tapped the starter and it fixed itself before, so.... any ideas?

djmtsu · 11-18-2009, 08:29 AM

Check the grounds, specifically where the large eyelet to the block near the starter. I have seen some crusty wiring in that area, especially if the car at one time had a leaky master cylinder.

Max777 · 11-18-2009, 10:41 AM

/\ ok. What if I do find bad wiring? Do they sell replacement wiring for the ctarting/charging circuit?

djmtsu · 11-18-2009, 12:41 PM

Not really, unless you can find a good 'power' harness from another FC.

The wiring on that side is MUCH easier to rebuild anyway. I saw the work you did on your other harness, this should be easy for you!

Max777 · 11-18-2009, 02:22 PM

i'm concerned about the big end eye bolt holes.... I cant seem to find where I can get some replacements done.

TehMonkay · 11-18-2009, 03:09 PM

You can buy off the shelf pre crimped wires at autozone etc, may have some slack though.

Max777 · 11-19-2009, 12:26 AM

/\ Cool. My oil pressure gauge has been acting up as well, so I'll deff tear into the charging harness this weekend and check out what's going on... I might pilfer some wiring from my old car now that I think about it... hehe

EDIT:

Ok, I seem to have figured out the hesitation issue, it almost HAS to be the starting system harness, I got a NCNS today, wiggled the wires again, and it was all fine and dandy.

Will the BOV getting stuck open lead to a sudden power cut? When I removed emissions, someone said to use a restrictor pill in the vac hose to the bov and map sensor. I didn't have one. Does anyone know what the pill is for? Should it be going just to the map sensor, or does it need to split to the bov as well?

Max777 · 11-23-2009, 07:31 PM

edited....

Max777 · 11-24-2009, 01:28 AM

edited...

NoDOHC · 12-15-2009, 11:42 PM

Did you ever get to the bottom of this?

It sounds like a short circuit on one of the large supply wires, either to the alternator or to the starter (I think that is where it goes). As I recall, there is a poorly-done factory splice below and slightly behind the fuse block beside the driver's shock tower.

I personally recommend a battery relocation, you won't believe how much better my '86 has worked ever since I relocated the battery (nothing original - behind the passenger's seat).

helghast7 · 12-16-2009, 02:48 AM

did you also check the main PCM ground under the UIM? if it has a bad connection many problems including hesitation will occur

also, slightly off topic, how the hell did you make 216 whp with a haltech and a no secondaries?

NoDOHC · 12-17-2009, 12:04 AM

Quote:

Originally Posted by helghast7

also, slightly off topic, how the hell did you make 216 whp with a haltech and a no secondaries?

4-port = turbo engine, only without turbo (taken from '88 TII).

The details are in the rotary performance section under intake manifold modifications.

Max777 · 12-18-2009, 11:27 PM

I did "Get to the bottom of this"... kinda

I ended up taking the S5 harness out of my other car, and combinging the big power wires with the S4 small gauge connector wires.

The "splice" that nodohc is talking about was corroded to all hell. The S4 harness uses a single alternator wire, and crimps it near the fuse box. The S5 harness runs TWO wires from the alternator instead, making the entire harness a better design.

IT turns out my starter is dying on me as well, because right after I did this, it got stuck, and the car started just fine after I tapped the solenoid... IT seems that the corroded wiring might have worn out the solenoid somehow, so coupled with a bad connection, my starter is old as well.

Luckily, the car has cranked like a champ ever since that fix. Right now, I got an optima yellow battery, a NAPA alternator, and rebuilt wire harness, so if the starter goes bad, it will be the last item in the "starting-charging" system that usually goes bad.

It's not as bad, but the hesitation is still there, so I am going to run a few extra grounds and see what happens.

helghast7 · 12-19-2009, 05:21 PM

if you clean off the main ground for the pcm the hesitation should go away, its the most common reason for the hesitation since its the ground for the PCM

Max777 · 12-20-2009, 04:21 AM

I'm pretty sure i did clean the main ground to the pcm... with a dremel and all, even put dielectric grease on it, i'll look at it again sometime,

unrelated, but could a stock bov sticking open make the car "fall flat on its face"?

11-18-2009, 02:11 AM	#1
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Blew the main fuse... Today, i did a decent burnout in the rain, (to show my friend the LSD) and the car just completely died in the middle of the street. I looked around and figured out the main fuse got blown. The fuse was 80amp, I put in a 100amp from s5, and drove it back home, but I'm afraid to drive it now. What do you think could have caused it to blow out? EDIT: I have had problems with the engine cutting out randomly while daily driving, and very noticeably during a drift practice session. I would start drifting circles, and the car would just "shut down", almost like a fuel cut.... I have an FCD, and my tank was full every time, so I dont think it's fuel or baffles. I think it is electrical, I had a no start, wiggled the wires and tapped the starter and it fixed itself before, so.... any ideas? __________________ Rotaries:They are NOT that complicated!

11-18-2009, 08:29 AM	#2
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	Check the grounds, specifically where the large eyelet to the block near the starter. I have seen some crusty wiring in that area, especially if the car at one time had a leaky master cylinder. __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

11-18-2009, 10:41 AM	#3
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	/\ ok. What if I do find bad wiring? Do they sell replacement wiring for the ctarting/charging circuit? __________________ Rotaries:They are NOT that complicated!

11-18-2009, 12:41 PM	#4
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	Not really, unless you can find a good 'power' harness from another FC. The wiring on that side is MUCH easier to rebuild anyway. I saw the work you did on your other harness, this should be easy for you! __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

11-18-2009, 02:22 PM	#5
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	i'm concerned about the big end eye bolt holes.... I cant seem to find where I can get some replacements done. __________________ Rotaries:They are NOT that complicated!

11-18-2009, 03:09 PM	#6
TehMonkay Rotary Fanatic Join Date: Apr 2008 Location: Louisville, KY iTrader: (0) Posts: 302 Rep Power: 17	You can buy off the shelf pre crimped wires at autozone etc, may have some slack though. __________________ My car blows up everytime I start it, it's rotary

11-19-2009, 12:26 AM	#7
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	/\ Cool. My oil pressure gauge has been acting up as well, so I'll deff tear into the charging harness this weekend and check out what's going on... I might pilfer some wiring from my old car now that I think about it... hehe EDIT: Ok, I seem to have figured out the hesitation issue, it almost HAS to be the starting system harness, I got a NCNS today, wiggled the wires again, and it was all fine and dandy. Will the BOV getting stuck open lead to a sudden power cut? When I removed emissions, someone said to use a restrictor pill in the vac hose to the bov and map sensor. I didn't have one. Does anyone know what the pill is for? Should it be going just to the map sensor, or does it need to split to the bov as well? __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 11-24-2009 at 01:30 AM..

11-23-2009, 07:31 PM	#8
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	edited.... __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 11-24-2009 at 01:30 AM.. Reason: too many posts.

11-24-2009, 01:28 AM	#9
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	edited... __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 11-24-2009 at 01:30 AM.. Reason: too many posts

12-15-2009, 11:42 PM	#10
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin iTrader: (1) Posts: 855 Rep Power: 17	Did you ever get to the bottom of this? It sounds like a short circuit on one of the large supply wires, either to the alternator or to the starter (I think that is where it goes). As I recall, there is a poorly-done factory splice below and slightly behind the fuse block beside the driver's shock tower. I personally recommend a battery relocation, you won't believe how much better my '86 has worked ever since I relocated the battery (nothing original - behind the passenger's seat). __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

12-16-2009, 02:48 AM	#11
helghast7 F yo couch! Join Date: Dec 2009 Location: Belleville, NJ iTrader: (0) Posts: 223 Rep Power: 15	did you also check the main PCM ground under the UIM? if it has a bad connection many problems including hesitation will occur also, slightly off topic, how the hell did you make 216 whp with a haltech and a no secondaries?

12-18-2009, 11:27 PM	#13
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	I did "Get to the bottom of this"... kinda I ended up taking the S5 harness out of my other car, and combinging the big power wires with the S4 small gauge connector wires. The "splice" that nodohc is talking about was corroded to all hell. The S4 harness uses a single alternator wire, and crimps it near the fuse box. The S5 harness runs TWO wires from the alternator instead, making the entire harness a better design. IT turns out my starter is dying on me as well, because right after I did this, it got stuck, and the car started just fine after I tapped the solenoid... IT seems that the corroded wiring might have worn out the solenoid somehow, so coupled with a bad connection, my starter is old as well. Luckily, the car has cranked like a champ ever since that fix. Right now, I got an optima yellow battery, a NAPA alternator, and rebuilt wire harness, so if the starter goes bad, it will be the last item in the "starting-charging" system that usually goes bad. It's not as bad, but the hesitation is still there, so I am going to run a few extra grounds and see what happens. __________________ Rotaries:They are NOT that complicated!

12-19-2009, 05:21 PM	#14
helghast7 F yo couch! Join Date: Dec 2009 Location: Belleville, NJ iTrader: (0) Posts: 223 Rep Power: 15	if you clean off the main ground for the pcm the hesitation should go away, its the most common reason for the hesitation since its the ground for the PCM

12-20-2009, 04:21 AM	#15
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	I'm pretty sure i did clean the main ground to the pcm... with a dremel and all, even put dielectric grease on it, i'll look at it again sometime, unrelated, but could a stock bov sticking open make the car "fall flat on its face"? __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 12-20-2009 at 06:20 PM..