ssj2link

iTrader: (15)

i have an 88 L98 motor in a 1990 trans am. i swapped it from TPI to carb and im having problems that i dont really understand. i took out the COMPLETE wiring harness and ECU. then i realised that obviously nothing now will have power so i took the harness apart. i learned that the bulkhead ( on the driverside ) was basicallyt a seperate harness. so i plugged that part back in to the car. now the heavy purple wire going to the starter is hooked up and so is the red of the red wires and the positive. however when i turn the key i get nothing. the rest of the car has power but that dosnt at all. so i spliced a wire into the purple one and ran it straight to the battery just to see if the starter was dead. that worked at the starter turned flawlessley. so im lost big time. can anyone help me out. also the fuse is good at the fuse block

squirted1

iTrader: (2)

I have seen many threads on here where the VATS is what seems to be holding people up. I'm not real familiar with it but, from what I understand, the VATS shuts down the vehicle start circuit as well as fuel and ignition. Some one who knows more about may chime in. Try a search for bypassing VATS

ssj2link

iTrader: (15)

i have read that before as well but what i dont understand is with the TPI it cranked and started no prob and im still using the same key.... thats why im confussed

ruiterman

VATS has two functions.

1. Remove power from the starter solenoid to prevent the car from turning over -- this could be the cause of your starter issue

2. Prevent the ECM from firing the fuel injectors so the car won't run -- you changed to carb, so really probably not your issue.


So really it comes down to one of two things, fuel or spark. You didn't say what you did for fuel pump/regulator. Do you know there is fuel? Did you keep the electric fuel pump and run power direct from key power? or still through the ECM? If you kept the electric fuel pump and didn't change the power from the ECM, you only get 2 seconds of fuel pump running before the ecm cuts it off (until enough oil pressure to get it going again).

Did you put the ECM back in too? If not, then the pump won't run at all unless you direct wired it.

Just some thoughts. Since I don't know your complete setup, these may or may not be helpful.

Ed

ssj2link

iTrader: (15)

i took out the old pump and put in a holley red pump and i wired that in. that is not running now cause i have not wired it up, however i know it works cause i can touch that to positive and that works lol. the dizzy i dont have wired yet either i have a GMPP one with vacuum advance. right now all im tryint to do is figure out why it wont crank with the key. and no i have no ECU anymore at all. sounds like it could be the VATS but i thought as long as u use the same key it wont matter????

ruiterman

You are right, with the same key, it shouldn't matter.

So that means either something else is wrong, or the VATS broke -- seems like a strange coincidence, but definatly possible.

I have two cars ('89 Camaro and '92 Bonneville) with VATS. The VATS broke on both of them 1 year apart -- and in the dead of winter no less.

When the VATS system breaks, it acts just like the park neutral switch is not in neutral. In fact, it is in series with the park neutral switch.

To trouble shoot this part of the VATS all you really need is an ohm meter. Basically there Key has a couple of connections that "read" the key. This is the most common failure.

Pull the lower panel off underneath the dash on the driver side so you can get to the steering column. On my '89 Camaro there is a small two pin connector near the base of the column. Find this connecor and unplug it. Use the ohm meter to measure the value of the resitor in the key. Then insert the key into the ignition and measure the resistance of the key as measured at the two pin connector. It should read the same. Make sure you measure the connector part that goes up to the key and not the part that goes to the VATS module. You do need to measure the resistance in all the key positions (off, start, run) to insure proper operation. On occasion it reads correct in off, but is bad in start or run.

If this is bad, you can just splice a resistor (with a value that matches the value of the key) into the line to bypass the vats. Or you can find all the wiring under the dash for where the power routes through to get power to the starter solenoid and bypass the VATS that way. If I remember right, there is another connector under the dash that you could just disconnect and put a jumer across two pins and you would be good to go.

I am assuming here that your Camaro is like my '89 and has the two pin connector. My '92 Bonneville had the pins for this as part of large 40 (or so) pin connector which was more difficult to deal with. It should be the two pin connector, which should be easy to find at the base of the steering column.

If this test passes and the key is ok, then you will have to trace the wiring diagram and see if there is some other power missing. It could always be the park neutral switch I or some problem in the line.

I know the ECM is not needed for this because on my '89 we switched to carb and the ECM is laying on the bench and it works just fine.

ssj2link

iTrader: (15)

hmm okay that is something ill try to look at and test out. also i have a B&M megashifter so my neutral safety switch isnt there. and is not functioning. i used to be able so start my car in any gear before ( starting in drive sucks and is scary lol ) so this is also possible. ill try the connector thing on monday when i have some time then. thanks for the help ill be sure to post back when i find out anything else

five7kid

iTrader: (14)

There is no reason not to have a neutral safety switch just because you have a Megashifter. It comes with the parts, so you need to install it.

buzzman1

five7 is dead on ...I put in a megashifter and the neut safety was pretty simple ..just follow the instructions and it should work. It sounds to me that the solenoid isnt getting powered that would tell me neut safety or vats or both, just swapped a carb into my 90 tbi and am having that fuel pressure issues of 2 secs of fuel.

ssj2link

iTrader: (15)

the only reason i didnt install the safety switch was because i bought it all used and i didnt get that switch and i cant find it for sale on the forum here. the fuel for me im gonna wire it right to a relay and have it turn on with the key. i think that is the easiest way to do that. my only concern is i dont have any of the relays on the firewall on the drivers side anymore ( i physically have them in my garage. ) so i dont know how to wire it to the point that it will go for like 2 sec. or does this kind of pump need to be running constantly when the car is on?

ruiterman

The electric fuel pump for sure needs to run all the time when the engine is running. With my car (and all the carb swaps I have read about) I just wired the power to the fuel pump relay direct from the ignition power (pink wire in my '89 TBI Camaro). Thus the fuel pump runs anytime the ignition is on.

Just remember you don't want to run from the ignition to the fuel pump direct, you want to keep the fuel pump relay -- you don't want all the current running to the fuel pump coming from your ignition switch.

five7kid

iTrader: (14)

http://store.summitracing.com/partde...part=BMM-80629
http://static.summitracing.com/globa.../bmm-80692.pdf

ssj2link

iTrader: (15)

wow u guys make it to easy lol. i have another question for you all then. what wires do i run to my distributor? do i use the heavy pink to the BATT and the white to the TACH?

five7kid

iTrader: (14)

If you're using a large cap/coil-in-cap distributor, yes.

ssj2link

iTrader: (15)

sure am. okay that worked no problem. now i cant seem to get the car started. i know i have fuel ( i have 7 PSI at the gauge ) but as i crank it all it does it crank and crank and crank. i checked for spark and i have spark also. now one attempt i hit the pedal and i got a pop out of the carb so i stopped, and right now its to dark to see anything. any one have any other ideas???

buzzman1

I would check the timing...I had good luck using the timing light during cranking to get the dist close after my swap
good luck
Buzzman1

ruiterman

I agree with checking the timing. And I would also make sure the dizzy is not 180 deg off too. Backfiring out the carb can defiinatly indicate timing, including 180 out.

ssj2link

iTrader: (15)

i want to thank EVERYONE that helped me. thanks to the help i have gotten I GOT HER STARTED THIS MORNING. it was the timing i had it 180 degrees off. now i have another issue i don't think its a bad issue just not sure where to start. the car will start up every time but if i don't give it some gas like 3k rpms it wont stay started. i THINK i have a vaccum leak but im not 100% sure. also im not sure how to "tune" the carb as this is my first one. also the fuel pressure is at 7 psi not sure if thats good or not either. anyway the car does start and it sounds like a BEAST again!!! THANK U ALL!!!

buzzman1

great news....I just got mine started after replacing the tbi with carb and it is a great feeling...