1989 Camaro 305 Tbi

Awhile back I was driving to work going about 60mph and the car just stalled... pulled over and tried to crank it but it wouldnt start. Noticed a blown 20amp ecm/fan fuse behind the battery. Replaced it and it blew again with the key in ON position. No fuel delivery.

Towed it to a mechanic shop. They said replace the fuel pump.
I bought an Airtex brand fuel pump from Autozone.
It started. Drove it home, and it stalled again. Same thing.
Towed it back to the mechanic shop.
Replaced the Engine Harness with a firebird harness for a 305 TBI 1990
Replaced the under dash Harness with another Camaro.
Replaced Fuel pump again
And also replaced the Fuel Pump Hanger.

Ran Like a champ for about a month. Then this morning on my way to work, it stalled again. Car cranks, No blown fuses, but no prime noise from the fuel pump. (Also the fuel pump would get pretty noisy, a whistling noise.)-some threads I've read say thats normal. What could have happened?

 

Well I believe if you have a fuel pump relay that would be a good place to look.

 

Partial or intermittent short in the harness leading from the front of the car to the fuel pump ?

Sounds like you've replaced just about everything else except for that harness and the ECM ... You did check/replace the fuel pump relay at least once during this , yes ? ..... Oh , and , wouldn't a partial clog in the fuel line/regulator cause the pump to draw excess current as well ???

Have you taken (or attempted to take) any fuel pressure reading during any of these incidents ?

 

I replace the fuel pump relay with the engine harness. Camaro harness had a rectangular sheaped Fuel pump relay. The newer one had a oval shaped one. How do you check the relays anyway? I haven't attempted. To check pressure. How is that done?

 

How do I bypass the fuel pump relay to check if maybe a wire has a short toward the pump. I replaced the relay... no luck.

 

Refer to a wiring diagram for your car. To bypass the relay, you jump the Batt circuit of the relay, pin E, to the load circuit, pin A. You can also use the fuel pump test terminal G of the ALDL. Jumping terminal G to Batt+ should activate the pump. If not, there is an issue either with the pump or the wiring to it.

I don't mean to be critical but in my experience it is better to test and verify circuit integrity than to simply swap out harnesses. Did anyone even verify grounds and power circuits? I've repaired more vehicle harnesses than I could ever count. I've only swapped whole harnesses when converting a carbureted or TBI car to TPI. I would suggest following the harness with a 12v test light at the pump and at each connection back to the ECM/FP fuse to verify power/no power at each point. Don't forget to verify ground to the pump module as well.

Airtex are not the best pumps. I quit using them after having to warranty a hand full in a single year. Bosch or AC Delco are a better choice. While pump noise is not always a sign of impending failure. It often does precede failure. So you may just have lost the pump. Verifying solid power and ground at the pump will help the new pump live alot longer. An earlier post refers to checking pressure and verifying no restrictions in the fuel line. This is a very good idea. Most pump manufacturers specify that you replace both the pick up sock and the in line filter when installing the pump in order to have the warranty honored.

 

 

Ok this is weird. After work I decided to check what would happen if I bypassed the relay, with my girlfriend in the car turning the key and trying to hear a hum coming from the pump. No luck. Thenbshe cranked it and it wouldnt crank! Nothing. Then I plugged the relay in and instructed her to get out. I then turned the key and, WALlA, the car turned on. I got all happy, but wasn't sure what the hell we did. Then two minutes later it died. What the ****?!

 

OMG that's a tough one might be a broken wire.

 

I was thinking maybe she accidently kicked a wire under the dash or. Steering column. I will do a 12v test light test of the system back to the pump. Ill keep you posted. Thank you guys for all of your help

 

That is weird. Try wiggle testing the harness with a test light connected to the batt+ terminal of the relay and then the ignition+ terminal, and finally with the test light between the Battery's + post and the relay's ground terminal. I suspect that the ground at the rear of the driver's side cylinder head may be loose. There is also a ground at the rear of the passenger side head. Check both.

 

I noticed today after work that at every crank of the car BOTHinjectors throwing out droplets of fuel into the tbi intake. It happens at every turn of the key. No spray. ?? Not enough to fire up.

 

Lots of times with 12 volts it is the ground like stated above.

 

The injectors fire every turn of the crank. The droplets/no spray mean you don't have fuel pressure.

 

You need to verify power and ground at the pump. If you have power and ground and no fuel pressure, listen at the filler neck with the cap off. Can you hear the pump running? If so and you still have no fuel pressure at the injectors, check the fuel filter for being plugged. If the filter is okay, you need to go into the tank. The pump will need to be replaced and you need to check the connections at the tank unit. You also need to be sure that the tank is clear of sediment that might be clogging the filter sock on the pump pick up. You must first verify whether the pump has power.

 

Well I believe if you have a fuel pump relay that would be a good place to look.

 

I think that would be a good idea.