I just finished my install on my '87 T2. I put in a new LT8S, got it all wired right put it all together and went to start the car. First I hooked up the battery then got in the car to start it. It cranked and seemed like it almost wanted to start but wouldn't fully fire up. I tried a few times and then took a break. Came back to it and now it seems like it only cranked with no attempt ti fire up, At this same time I noticed that the lights were not turning on, on the ecu. I figured the fuse blew since no lights were coming on. Went to the supplied 15 amp fuse and sure enough it was blown. With the ignition off and battery connected i plugged in a new fuse and it blew on contact. Next I disconnected the battery and put in a new fuse. As soon as I connected the battery terminal the fuse blew immediatly. What is really confusing me is why the fuse was fine for the first attempt and then blew immediatly for each new fuse. Need help please.

P.S. I'm gonna need somebody to tune it.

 

Update: I suspected a problem with the fuel pump relay so I flipped some wires around and still the same problem. Then my dad says that the ECU probably has a short in it. So I unplug the ECU and try it again, pop there goes another fuse. So I guess now i'm looking for a short in the wiring somewhere. As soon as I connect power, it takes about three seconds for the fuse to blow. This has turned into a month and a half Microtech install.

 

Yes, check the wiring. Most probably it will be a positive/negative wiring problem? Did you hook up the different 5V and 12V wires properly?

 

All the wiring looks good, tried the fuel pump relay a few different ways 'cause I suspected that, even disconnected the fuel pump, that didn't do it. Check the power supply cable and it looked good. Something is drawing a lot of power when off because when the battery terminal touches it gets a bigger spark than usual and then the fuse blows. I will try replacing the fuel pump relay with a new one. If that doesn't work look in the for sale section for my LT8S.

 

hahahahah so your going to sell it cause there is a problem in the wiring!! LOL

if the fuse is blowing there is a problem on one of the injector wires or power feed,

Dale

 

It's not the unit's fault it's blowing fuse. As Dale said, somewhere your wiring is crossed or getting grounded.

 

have you connected anything to the auxilary output on your microtech?

 

Yeah, i'm running the BAC valve to my auxilary. One aux. wire to the plug and the other grounded. The thing is with my LT8 it was programmed to run with my bac. So the two aux. wires ( white and blue I believe) are not connected to anything. Instead on my harness there was a grey wire with orange stripe that had a sticker on it hand written 'Aux Air'. So I figured that one was for the bac.

 

ok you still have the white wire which is a normal output that can be used for a fan etc,

you have the BAC hooked up incorrectly, the output on the ecu is a earth, you have to hook the other side of the bac to +IGN not earth,

 

sweet man! Thats exactly what I was looking for. I suspected the BAC because the wiring diagrams were unclear about the BAC wiring. I'll try it.

 

OK, So I the wire that I was running as a ground for the BAC I re-wired to 12V IGN. ON. This did nothing, the fuse still blows as soon as soon as the battery is connected.
Keep in mind that when I very first connected the system it worked for about two minutes, then something hapened that blows fuses every time.

 

ok have you checked that your injectors are not stuck and pulling heaps of current?? thats really the only thing that will blow a fuse...

 

The injectors were totally fine before. The car was running great when I took it apart to put in the Microtech. I connected the power supply not to the battery but to the alternator instead. It is the same un-interupted 12V I believe.

 

what happens if you disconect the injectors and try?

 

do a little test for my,. disconnect everything from the ecu bar the power in and see if it still blows the fuse (i mean injectors, coils (just unpluig the ign out harness) fuel pump relay, aux out, tacho etc etc)

 

Do you mean unplug the ecu from the harness and try to connect, because I already did that and it still blows a fuse. Or do you mean just unplug EVERYTHING and see if the short is somewhwere else. Also someonr mentioned to me that there might be a chance of one of the wires in the harness might not be plugged on the correct position on the ecu plug. what are the chances of that.

 

i mean unplug everything from the ecu, injectors, tps, fuel pump relay basically everything execpt the red, pink and brown wires and see if it blows the fuse

check the pinouts against your wiring digramme

 

where is your ground hooked up to ?

 

The ground is hooked up to the top of the rotor housing and the whole engine is grounded very well via a nice grounding kit.