Something blew up while trying to start supra

pseudoduck · 03-01-2013, 06:44 AM

Hey all. Got a 1986.5 Supra with a 7mge. I recently replaced the headgasket and just got it finished and assembled back together. I went to start it and it turned over, but barely. It started to run for a little bit on it's own but then died. I went to try to start it again and then there was a popping noise from the hood and a bunch of smoke coming from the front of the engine near the valve cover and the alternator. When I tried it again it drained my battery instantly and my tachometer went up to about 4000 rpms and then dropped. I found out I forgot to plug in a black plug on the throttle body. I got it plugged in now and I'm waiting for my battery to charge. Is my 7mge dead now? Should I try it again?

pseudoduck · 03-01-2013, 07:02 AM

Also, I think these could be another problem. I don't know where these wires were supposed to go. I figured they were ground wires so I bolted them to the intake manifold.

MA70-3.0GT · 03-01-2013, 07:20 PM

Think those should be earths (grounds) as you say, but can't see the wire colours to be 100%. not to insult your intelligence 'cos you already know the earths are black & lives red, but years of dirt can cover the true colour... Is it just possible that the alternator charge wire got hooked up to the earths by mistake (or an earth to the alternator output?) That upper terminal in the pic does look somewhat similar to the alternator wire...

A common problem is the fusible link in the battery cable failing although I'm not sure it'd give the same symptoms you had, it is in the general area you describe, perhaps check that it's intact & not corroded first off?

I guess you could just be unlucky in that your alternator just failed, they're not unknown to die in short order (no pun intended there!) sometimes related to using jump start/booster packs... And if a diode pack shorted out it could do something like that... maybe if that's suspect you could just disconnect the wires to it & try starting with fully charged battery to see what happens?

pseudoduck · 03-02-2013, 06:53 AM

Well the wire colors are brown and white. And I don't remember where I took them off of. But I did get my car running. I charged the battery back up and plugged in my throttle position sensor and it runs. But the idle is VERY ROUGH. And there is a kinda loud hissing noise coming from somewhere near the alternator.

Sonyps307 · 03-02-2013, 11:59 PM

Looks like the grounds for the ecu they bolt to the bottom of the intake

MA70-3.0GT · 03-05-2013, 10:33 PM

Hissing from under the alternator would likely be a vacuum line off, I think there's 2 or 3 lines in that area. that would also throw the idle out.

03-01-2013, 06:44 AM	#1
pseudoduck Stock Join Date: Mar 2013 Location: Washington Posts: 4	Something blew up while trying to start supra Hey all. Got a 1986.5 Supra with a 7mge. I recently replaced the headgasket and just got it finished and assembled back together. I went to start it and it turned over, but barely. It started to run for a little bit on it's own but then died. I went to try to start it again and then there was a popping noise from the hood and a bunch of smoke coming from the front of the engine near the valve cover and the alternator. When I tried it again it drained my battery instantly and my tachometer went up to about 4000 rpms and then dropped. I found out I forgot to plug in a black plug on the throttle body. I got it plugged in now and I'm waiting for my battery to charge. Is my 7mge dead now? Should I try it again?

03-01-2013, 07:20 PM	#3
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	Think those should be earths (grounds) as you say, but can't see the wire colours to be 100%. not to insult your intelligence 'cos you already know the earths are black & lives red, but years of dirt can cover the true colour... Is it just possible that the alternator charge wire got hooked up to the earths by mistake (or an earth to the alternator output?) That upper terminal in the pic does look somewhat similar to the alternator wire... A common problem is the fusible link in the battery cable failing although I'm not sure it'd give the same symptoms you had, it is in the general area you describe, perhaps check that it's intact & not corroded first off? I guess you could just be unlucky in that your alternator just failed, they're not unknown to die in short order (no pun intended there!) sometimes related to using jump start/booster packs... And if a diode pack shorted out it could do something like that... maybe if that's suspect you could just disconnect the wires to it & try starting with fully charged battery to see what happens? __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!! Last edited by MA70-3.0GT; 03-01-2013 at 07:31 PM.

03-05-2013, 10:33 PM	#6
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	Hissing from under the alternator would likely be a vacuum line off, I think there's 2 or 3 lines in that area. that would also throw the idle out. __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
No Start supra	bmwbradford	MKIII Supra	4	11-09-2010 09:15 AM
Questions about MKIV Supra	ukno0003	MKIV Supra	5	11-06-2008 10:53 AM
89 Supra Won't Start	clwilli	Non-Generation Specific Questions	3	10-03-2008 03:27 AM
87 Supra 7M-GTE/AT Engine cranks over but doesnt start...	Supra-Boy	MKIII Supra	7	03-15-2006 11:38 PM
where do I start in upgrading my supra	Robert Winterbottom	MKIII Supra	4	07-02-2005 07:47 PM

03-01-2013, 07:02 AM	#2
pseudoduck Stock Join Date: Mar 2013 Location: Washington Posts: 4	Also, I think these could be another problem. I don't know where these wires were supposed to go. I figured they were ground wires so I bolted them to the intake manifold.

03-02-2013, 06:53 AM	#4
pseudoduck Stock Join Date: Mar 2013 Location: Washington Posts: 4	Well the wire colors are brown and white. And I don't remember where I took them off of. But I did get my car running. I charged the battery back up and plugged in my throttle position sensor and it runs. But the idle is VERY ROUGH. And there is a kinda loud hissing noise coming from somewhere near the alternator.

03-02-2013, 11:59 PM	#5
Sonyps307 Lexus & 550's Join Date: May 2010 Location: Baltimore Posts: 526	Looks like the grounds for the ecu they bolt to the bottom of the intake