I recently changed my fuel pump. The car turns on and runs for 20-30 seconds, but then it shuts off. The injectors shoot gas out, but after those 20-30 seconds it stops. I have a holley 670 cfm tbi. Any advice?

The cars a 89 305.

 

it could be a defective pump....

Is the fuel pump the only thing you changed from when it ran to now? Maybe if your sure the pump works, toss the stock throttle body back on and see...

 

'0834

I would check the reference signal line from dizzy. If, for what ever reason the dizzy stops sending ref_low signal to ECM the ECM in turn would shout down injectors and FP.

But first you should perform a static fuel pressure pump test. Locate fuel pump relay - on most F-bodies there is a red wire pig tail attached to the FP relay socket. Connect at least #14 gauge jumper wire to positive battery terminal. This will immediately power-up FP. You can verify FP performance with a fuel pressure gauge connected right at the TBI body. Listen to the pump while keeping an eye on the fuel pressure gauge. For a stock TBI it should be around 13 PSI. If the pump stops within 20 sec - check FP relay contacts and socket for discoloration. Otherwise pump is history.

If pump keeps on working then you have to dig a bit deeper. First check all wiring around FP relay socket - any discoloration indicates a circuit drew excessive current!!! Check relay - older relays may have intermittent windings and or pitted contacts.

If FP relay checks OK then you'll have to do couple reference checks. This may involve verifying a reference signal received by ECM from Dizzy on B3, checking grounds, etc, but check the easy stuff first.

I hope this helps

//RF

 

I was just wondering if it always happens even if just starting it or if it initially starts for a couple of minutes and then dies?if it starts runs for 2 or 3 minutes then dies then will not start after that it could be as simple as a MAP sensor being bad!the car will run in open loop with all its preset numbers till everything warms up and then the computer will go into closed loop and take reading from sensors to make its numbers!If a sensor is not working it will shut down at warm up temp!

The vaccume hose for my MAP was plugged and that was what happened to me!just another possibility!It is a simple place to start!Hope i helped!?

If not sorry!

 

Thanks i'll check those things tomorrow