I have an 88 gta which had a 350 tpi that had a rod knocking. So I got hold of a 86 305tpi cheap. I do plan on rebuilding the 350 just short on cash right now. I got the 305 in the car and now it starts but will only run for 2 seconds then shut down. I keep the computer that came with the car in. The car does have the vats system. Could that have anything to do with it? I did use the dist. out of the 350 so the wiring would work. There was only one temp sensor on the passanger side that was not in the 305. I didnt get it in the block yet but I have it grounded for now. I did install new cap,rotor,mod, in the distrubator. If anyone knows what it might be that would help. Im been trying to get this thing to run for a month know.

 

Fuel pressure?

 

Sounds like you may not have the oil pressure switch connectec that signals the fuel pump to run. When you turn the key on the computer will prime the fuel pressure for a few seconds and then the fuel pump won't run again until the engine builds oil pressure. The reason it only runs 2 seconds is because you are only running on the prime pressure.

At this time, I don't remember what the temp sensor on the passenger side is for, but don't ground it off. If you ground that wire then the car thinks it is overheating.

One thing you didn't mention. Did you put the 305 chip in your computer. If it is running the 350 chip, it will run rich, if it will run at all.

 

Except the oil pressure switch does not solely power the fuel pump once the system runs. It acts as a back up to the fuel pump relay, which is the constant power source, as long is it is operational status. It primes the system, yes. That suplies enough fuel to get the motor turned over and create a distributor reference pulse. Once there is a distributor ref. pulse that is detected, that powers the pump, via the relay.

The sensor in the passenger side of the block has nothing to do with engine temperature. That is the knock sensor. Unless you are talking about the passenger side head, in which case that would be a fan switch. Which are you refering to?

You should get a different chip (PROM), 305 ESC, and a 305 KS to help you. (Basically backwards of a 305 to 350 swap).

Fuel pressure and ignition system (that includes all the spark control components) would be my starting points.

 

Correct me if I'm wrong, but the oil pressure switch is a fail safe for the motor. It oil pressure drops, the switch opens the curcuit and kills the fuel pump. Thus, killing the motor, trying to keep as little damage to the motor as possible.

 

I corrected you above.

Go unplug your pigtail off the switch and watch the engine cut out.

 

You are right!!! I just looked through my wiring diagrams and found my mistake. I'm wondering why it is like. This makes no sense. The chances of losing your fuel pump relay and having to rely on your oil pressure switch???? I think I'm going to rewire mine so it works as a fail safe, if my oil pressure drops. That has a lot more use for me.

 

I'd say it's running rich because you didn't use a 305 computer, you re-used the 350 computer with the 350 chip. Am I right? If I am...there's your trouble. 305's had smaller injectors and required less fuel. The 350's biggest limitation was that the T.P.I. units it used were designed for the 305. Since we were all screaming for a 350, they put the T.P.I. unit on a 350 and gave it bigger injectors and a different tune to "Git R Done"!

 

Yeah, as stated earlier check all your connections, replace the prom\computer crap, if you used the 305's knock sensor your alright. I dont believe that the vats have anything to do with the engine rather than allowing the fuel injectors to fire, since your starting up thats not a worry. Your probably just flooding the engine, or settting off a sensor. Nothing big. If anything ask around with people that have done engine swaps from 305 to 350 engines and ask for their old computer crap.

 

I put the 305 chip in the computer. The computer in the car looks new its a remanufactored. I Checked all the connections, they were good. Still the car starts and then stalls. The first start up it runs for about 4 sec then if I keep on trying to start it it runs less then eventually does not run at all, just cranks. Ive been checking the oil and there is no gas in the oil, and I cranked it about a 100 times by now, so I thinking it is runing out of fuel. The fuel pressure is at 42psi and has spark. Something has to be shuting the injectors down but I just cant figure out what. The car ran fine before engine change just a rod knocking.

 

Here's my suggestions then:

1. Check your electrical connections at your coil, alternator, distributor, E.C.M. as well as the electrical connections to and from the injectors.

2. Replace the fuel filter and see if that corrects the problem.

3. Check your fuel lines for flow to make sure you don't have any blockage.

4. Check to see if your intake manifold is leaking or has loose bolts.

5. Check all of your vacuum hoses. Especially the ones connected to the intake manifold. If you have any doubt as to the vacuum hoses ability to do its job, replace it.

6. Other than that, I'd have to suspect that your fuel pump is getting weak and might need to be replaced.