This past weekend my Dad picked up an abandoned Fiero project and I want to help him figure out just what he has gotten into.

The car is titled as and appears to be an ’84 that was a manual trans car. It currently has a 2.8 V6 with an auto trans in it. This car has passed through several owners since the engine was swapped into place, so the history is pretty much lost. The way we understand it, the engine was a good runner before being swapped into this car and they never could get it running again after it was swapped. At first glance this car looks like a total hack job and it really had us worried – the wiring is a mess! I did some research on this site and we decided to change the fuel pump – it did not look like this had been done. After this we could get the car to fire on a cylinder or two but it would not run. Then I remembered that when I got my ’86 V6, one of the fuel injection fuses was missing causing it to run on only 3 cylinders. We checked the fuses on Dad’s car and found the INJ2 fuse was blown. We put in a new fuse and it instantly blew when the key was turned on. We the traced the wiring and found that the pink +12v wire (K at the C203 connector) was the problem. We traced it into the engine compartment where it had a factory crimp connection that split it into two wires. One wire went to the fuel injector plug (at the fuel rail) and the other had been connected to some mystery black wire at the passenger side firewall. We disconnected the black wire and it quit blowing the INJ2 fuse. After this (and some other things) we managed to get the car running although very poorly. By pulling the spark plug wires one by one while the engine was running, Dad found that the number 5 and 6 cylinders are not firing. He checked compression and spark, and it has both so we assume there is a problem with the injectors. Does anyone know where the wire that split off (from K at the C203) is supposed to go?

The way I understand this injection system, is that it is a batch fire - as in injectors 1, 3, and 5 fire at the same time from the same signal and 2, 4, and 6 fire at the same time from the same signal. There is really only two injector pulse signals, one for the 1, 3, 5 bank and one for the 2, 4, 6 bank – right? This would mean that if the engine is running on cylinders 1, 2, 3, and 4, that injectors 5 and 6 should be getting a signal unless there is a problem in the harness at the injectors themselves. In that case, would it be likely there is a problem with the injectors on cyls 5 and 6?

As far as the condition of the car… After several days of researching this forum I have learned a lot about the peculiarities of the ’84 cars. It appears that the previous owner did go through a lot of trouble trying to do this right. Maybe they got desperate in the end when they couldn’t get it running and started hacking wires??? The car has a wiring harness lying in the spare tire compartment – as in completely disconnected! This harness has the fuse panel on one end and there is no provision for a fuse in the INJ1 and INJ2 locations. Is this the original ’84 4cyl wiring harness? As in the previous owner completely changed out the interior wiring harness? Also, I keep reading about how the ’84 has the C500 connector on the firewall, but on this car it is by the battery tray! Does this mean they have changed this wiring harness also? This is where the wiring on this car gets messy. They have cut all the wires from the C500 and ran jumper wires (as in twisted the wires together and left them bare!) over to a bank of relays that are mounted on the engine side of the firewall behind the driver seat. Some of the wires are not connected to anything!

Please help figure out what we are dealing with here! …Thanks.

Your right about the injectors.
Do you have a drawing..

http://www.euronet.nl/users/fo_elmo/fiero09.pdf

That's what I keep running into... See in that wiring diagram on pin K, circuit 639, it shows splice S516, but it just shows an arrow going off to the side that says Multi-Port Fuel Injection (Emission Controls). I think that's our mystery wire. Where does it go? I can't tell from that diagram.

Dad, you reading this? Did you sign up for this site yet? Did you get a good wiring diagram yet? You might check the connectors on the injectors just to make sure their not corroded or something simple like that. I think, if you can get your hands on a couple of injectors from say a 3.1 engine, you could try them and see if that gets cyls 5 and 6 going. Does Bill have any of those laying around up there? Also, does that car have any tail lights? I think about half of those wires that are all hacked up from the C500 connector by the battery are for the rear light harness. You might get lucky and be able to just pick another tail light harness from a salvage yard and fix a good protion of that mess. I'm still not sure about the rest of those wires though.

Just so I'm not confusing all of you guys out there... I'm 32 years old and I live in Southern Indiana while my Dad lives in Northern Indiana. I just happened to be up there visiting him this past weekend when he dicided to get this car. So. I helped him with it for a couple days while I was there, but now he's kinda on his own. He is the new Fiero owner, not me - I've had my '86 SE V6 for a couple years now. I told him about this site and convinced him you guys could help him straighten out this car.

[This message has been edited by lcorrell (edited 02-23-2006).]

http://www.euronet.nl/users/fo_elmo/fiero08.pdf

If you check the previous dwg, the ckt from the TBI Fuse #2 fuse feeds both the cyl 1/3/5 injector module and an EVRV ( electronic vacumm reg valve) thru the splice @ S516. Look at both dwg #8 and dwg #9

This may be a little off the wall idea--but has worked for me---grab a new harness and c-500 from ebay or the mall here on the forum, then drive your car over to your Dads house and set them side by side, then duplicate whats on your car to his. Yes that extra harness you found belongs to the 84, and the c-500 is by the battery tray on the 2.8`s. The bare wires alone could be shorting out your injectors, the wires & relays you mentioned headed towards or behind drivers seat on firewall are the fuel pump relay on the right and a/c relay on the left. Hope this helps some... Welcome to the Forum/Madness

Can an 84 even run a v6? I was under the impression that the lack of the c203 connector really created problems for that car.

You have the right idea, now I might be wrong here, but I seem to recall that the injectors are not banked like 1-3-5 but something like 1-3-6 or something allong those lines. Check the actual wiring to the injectors to see, but I seem to recall this being the case when I was flow testing a rail I had. There were 2 side by side then one on the far opposite side.

But regardless, if one is firing they all should be firing unless an injector is bad or the fuel rail wiring has been hacked. There are 6 wires to the rail, 1-2 for a set, 3-4 for a set, and 5-6 for the cold start injector.

You might try unplugging the fuel rail from the engine harness and feeding the engine on starting fluid.

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Thanks jazz4cash for pointing out that second drawing. I see where that wire is supposed to go now.

Does anyone know if that EVRV is the EGR vacuum solonoid? I think this car is missing the EGR solonoid.
*edit* That would explain the wires that don't go to anything. *edit*

Is the C500 part of the interior wiring harness? I think the wiring up to the C500 connector is OK on Dad's car. It's the stuff that plugs into the C500 that's hacked up.

Thanks for the help, and keep it coming...

[This message has been edited by lcorrell (edited 02-24-2006).]

quote Originally posted by lcorrell: Thanks jazz4cash for pointing out that second drawing. I see where that wire is supposed to go now. Does anyone know if that EVRV is the EGR vacuum solonoid? I think this car is missing the EGR solonoid. Is the C500 part of the interior wiring harness? I think the wiring up to the C500 connector is OK on Dad's car. It's the stuff that plugs into the C500 that's hacked up. Thanks for the help, and keep it coming...

I wouldn`t worry about the egr solenoid right now, C-500 is not part of interior wiring harness ,

**** It's the stuff that plugs into the C500 that's hacked up.*******

Thats why I suggested above , about getting another harness and C-500 block from ebay of here in the mall section--will save you alot of time and head-aches--now & later. One thing Gm did in our favor is make there connectors so they really only fit one way, its not that bad/hard to go that route.. Hope this helps some.....

according to the fact svc manual, for the 88 v6 anyway, it's 1,3,5 and 2,4,6.

Now one thing, there is a connector for the fuel injector harness, it should be right up by the cyl1 manifold passage, directly under the map sensor, buried in the mess of hoses and wires. this would certainly be a nice test point. and a possible failure point, as I recall, I didn't think this was the most robust connector for where it lives. if it truly is cyl 3 and 6 not getting fuel, you should be able to see a pulse there. it is called connector C520. pin a is pink/wht and is hot 12v to injectors2,4,6 , pin b is lite grn/blk and goes to the ecm, and will go to ground when firing an injector. pin d is pnk, feeds 12v to injectors 1,3,5 and pin c is lite blu/blk going to the ecm. with a good analog meter, you should be able to see the pulse to ground flick the needle from 12v when firing an injector.especially at starting cranking, when it uses a longer duration pulse.
up to that connector, all is common, so if one fires they all fire. so fi you are sure 3,6 are dead, it would point to either 2 bad injectors, or a break in this harness. Pull the #3 sparkplug. if it's wet, and smells of gas, then the injector is somewhat working, and the problem may not be the injector.

Hope this helps...