1988GTA500HP

Last month I bought a 1988 GTA for my son who is getting his permit in February. My plan is to teach him how to work on it and fix the car up before he gets his license. The car was originally a TPI and the previous owner swapped the engine out to a 400 CI carbureter motor. He used MSD ignition system but never hooked up the tach to the coil. From my repair manual I know the tach wire is white. However, there are soooo many disconnected wires throughout the car that identifying which one is the tach has been challenging.

1. Can anybody tell me where EXACTLY the tach drive should be found in the engine compartment. I don't even know if the car originally had a stand-alone tach or one mounted in the distrubutor cap. And did the tach ground also enter the engine compartment or was it grounded in the passenger compartment?

Also, from browsing this forum I know the proper way to convert the fuel pump would be to drop the fuel tank, remove the fuel pump, replace it with a pickup, and add a mechanical or electric fuel pump with a return to the tank. Presently the car has only a 2 line fuel pump, 1 in and 1 out. They capped the return line in the engine bay. The previous owner told me they disconnected the fuel pump because of too much pressure and advised me not to reconnect it. I found the shop that did the final touches on his swap from some receipts he gave me. I called the shop and asked where they disconnected the fuel pump, because the gas guage no longer works. He told me they dropped the tank and disconnected it. I find this hard to believe because why would you go through all the trouble of dropping the tank and then not bother to hookup the gas float.

2. Anyone have an idea of where they may have disconnected the fuel pump. I checked the wires under the rear carpet and they didn't cut those lines.

Any help would be appreciated and my son absolutely loves his car. It is pretty quick.

ZONES89RS

iTrader: (2)

I think it foes thru on the driver side of the direwall under the brake booster if i remember correct.

But then again, i usually run an aftermarket so i am a bit hazy remembering this.

five7kid

iTrader: (14)

Welcome aboard thirdgen.org.

I hate having to work with someone else's hack job. But, all is not lost, we'll try to help you through it.

In the '88 model year, the factory used a small cap distributor with a separate coil. The tach wire went to the coil, not the distributor. The wire is in what's called the "C100" bulkhead connector, to the outside of the brake booster in the rear corner of the engine compartment. Here's a link to some diagrams http://www.team3rdgen.com/modules/3rdGenLS1/Wiring.htm . The '88 model year isn't shown, but note they are all D6, white wire.

You can use the factory in-tank electric pump with a carb. You just need to use a return-style regulator that drops the pressure down to carb-friendly 4-6 psi like the Mallory 4309. You can check for the presence of the pump by reading the resistance across the pump power wires. If it's open, at least the pump has been disconnected electrically. About the only way to know for sure is to drop the tank and pull the pick-up. There is a sticky in the top section of the Carburetor forum that details how to convert an in-tank electric pump pick-up for use with an external pump. Personally, I'd use the in-tank pump if it were available. (If you do go ahead and drop the tank, put in a new pump - a 22-year-old pump shouldn't be trusted. The Walbro 255 is a popular choice when replacing the factory pump.)

Are you saying the gas gauge isn't working either? There isn't any reason to not hook up the float just because you removed the electric pump. But, people do some strange things.

1988GTA500HP

Thanks again for your help.

naf

iTrader: (7)

Look for the fuel pump relay, hopefully the attached will help with component locations.

If the four wire connector you found is square-shaped, it's likely the transmission connector that commanded lock-up and told the ECM when it was in fourth gear. It would plug into the case above the shift linkage, but you'd have to feel for it's presence as the plug faces upwards.

1988GTA500HP

Thanks Naf, I printed that out too. The connector was 4 straight across, not 2x2, if that want you meant.

naf

iTrader: (7)

Four-wire, straight across could be the fuel pump relay connector. If the colors don't help you could check continuity between one of the leads and the oil pressure switch which should be/was teed off the china wall near the distributor. The connector for the OPS is a two wire plug. The relay control lead was grounded by either the ECM or the OPS. If you don't have one, see attached:

Pocket

iTrader: (24)

https://www.thirdgen.org/forums/ltx-...formation.html

Pretty much every C100/C207 for all yea 3rd gens. It should be white C100 pin D6 for your car