Hello All. Please forgive me if there is clearer information around that I should have found. I have searched but find only partial information.
I have a 89 TBI 305 that does not start. It starts if I feed gas at the TBI but the pump is not priming nor pumping gas to the TBI.
Before I go to drop the tank I want to be sure that the pump is the culprit. I have read around here the existence of some test method that will force the pump to run. Can anyone provide details to such method?
I have checked the relay and found no apparent issue there. I do not know where the fuse if any is located so I have not checked for that.
Thanks in advance for any help.

jim

 

You may have dead FP relay or blown FP circuit driver transistor in the ECM. To see if your FP is operational apply +12 volts to G terminal of ALDL connector - this should run FP with engine off. FP relays are robust but I have seen a few that failed to close circuit.

//RF

 

Thanks for the suggestion RF master. I have tried that and was unable to hear the pump prime. I will try in the morning again with more light. It seems more and more that I will have to drop the tank.
regards,
jim

 

I forgot to mention that upon turning the ignition on, the relay does nothing. It does not move at all. Not sure if the control for it comes from the ECM but this car has not been driven in a long time (2yrs). I just purchased it.
I will be getting a manual tomorrow to analyze this in more detail before I begin with the tear down of the tank :-(

 

You should perform a basic POST test:

Move ign key from off to run position (do not crank). SES should go from solid on - off - on this would indicate that ECM performed internal self check. During POST ECM will power up FP relay for about 2-3 seconds. You can pull FP relay from its socket - get a DVM and insert test probes into relay coil socket pins (85 and 86 - usually dark green (pos) and black/white (gnd) wires 16AWG) - and measure DC voltage. If you get +12Volts for about 2-3 seconds during POST then ECM is providing control voltage to FP relay coil. While you have relay out verify that you have +BAT voltage present at PIN 87 - large diameter orange wire (10AWG). Be careful this wire is connected to + Battery terminal! The gray wire leads to in tank fuel pump. Post your findings.

//RF

 

Thanks for the suggestion RF master. Will do as soon as the sun breaks this morning lol.
Will post back with results.

 

Well, I replaced the relay and now I can hear it click with the ignition on and then click again after a few seconds so I suppose the ECM thing is working. I did not check for 12V at pin 87 as suggested. I will do that in the morning. I will also then check the pump harness in the back of the car for the presence of 12V. That is if it is accessible.
It looks more and more that I need to drop the tank :-(

will report back with results lol

 

You can always pull up the carpet over the rear hump and cut a hole in the sheet metal. Be careful because the tank and lines are directly under that sheet metal. Don't run a drill straight down to start your hole! Use a tubing cutter on the gas lines and reconnect them with compression fittings.