HELP! Just bought a 1989 Trans Am that has been sitting for 3 years. Popped in a new battery and everything came on and worked, lights, windows, locks etc. When you turn the key, fuel pump does not come on. We replaced that and the fuel pump relay but pump doesn't come on unless we put a wire from the battery to the diagnostic terminal under the dash - then it works. Car will not start and I noticed that the CHECK ENGINE light doesn't come on when you turn the key to run - -someone told me that this could mean that the ECM is fried??? We have checked and we have fuel going to the throttle body injectors and we have power on those, we also have the engine firing. Can anyone offer me any help? Someone said in here that the ECM controls the fuel pump relay - so if it is fried the pump won't work?

Thanks!!

 

There is an inline fuse under the hood. The wire with the fuse in it runs along the fender line on the passenger side (US pass). This fuse is power for the fuel pump and the ECM. It may be that it is bad.

The ECM controls the fuel pump relay. There is also an oil pressure switch that will enable the fuel pump (direct to pump, bypasses the relay). If the engine has been cranked long enough to build a little oil pressure that switch will close and enable the pump. But, the forementioned fuse needs to be good.

RBob.

 

thanks for that tip! I did c heck the ECM out and it is in fact bad. The guy that had this car bought it from someone that had changed the engine out and put the engine from an 87 Trans Am in the 89 Trans Am. He said it worked for a while - -then he had problems - some mechanic changed out the computer and put in one from an 88 Trans Am with multiport fuel injection and the car didnt' run -- i bought it with this computer and I'm finding all this stuff out -- can someone tell me what computer I need for this car? GM doesn't manufacture it anymore and I don't have a PROM for it either since it is the wrong computer period! HELP!! I have been looking on EBAY but am not sure what to get - my car's VIN number calls for an E code ECM for 1989, but I have an engine from an 87 which has vin code F. The car has throttle body injection - how do i choose the right computer for the car to run?

HELP!! Thanks

 

You can run one of a couple different ECMs. An '89 f-body with TBI uses the 1228746 ECM. Also found in Caprice's. If the engine is still a 305 then the stock calibration should still work decent.

If however the engine is a 350 or modified you may need to change the calibration. Same ECM, different calibration and larger injectors are required (for best performance at least).

Other ECMs are plug and play, mainly the 1227747 as found in trucks (a lot of trucks). Can get one from a full size van that has the same engine size and transmission as your vehicle. And if 350 to 350 can grab the injectors for your vehicle.

RBob.

 

Can I use an ECM from a 1988 Trans AM with the same engine?

 

That would be the 1228063. Should work.

RBob.