Trying to figure out why my 91 Firebird 305 TBI 5-speed will not start. After installing the new fuel pump I am still not getting any fuel. Not sure if ignition might be it due to it keeps not engaging the starter all the time. When it stopped running years ago I did not have the issue of it not engaging the starter and now it takes 2 or 3 times of trying to start then it starts cranking. It has a brand new battery, starter, and fuel pump. Thought the other pump was locked up due to not hearing it and pump was hot to the touch but believe there is something else wrong that I can't figure out. I have spark but no fuel. Could it be the fuel relay? I'm getting clicking noises at the TBI injectors and something clicking in the back of the intake that I cannot seem to find. So if anyone can point me in the right direction, I'd appreciate it!

 

just wondering , since our fuel pumps are mounted in the tank how you were able to determine it was "hot to the touch" ?

Anyway , no pressure to the injectors = no starting , so you have to find out why the pump won't run . Did you check the fender mounted fuse that feeds the pump & ECM ?

 

I put a trap door in the back of the trunk about 6 or 7 years ago when I changed to a Holley pump when I was running nitrous.

​​​​​​​I haven't checked the fuel pump relay yet but will this coming week when a get back into the shop. I do believe that the fuel pump relay is right next to the brake booster? There's two relays right by each other and the main wiring harness goes into the firewall?

 

Jim , I'm enclosing the schematic diagram for the fuel pump . You will see that in addition to the relay there is also an oil pressure switch in parallel with the relay , meaning that even if you were to remove the relay entirely the car should still start after enough cranking of the starter builds up enough oil pressure to close the switch and run the pump . In fact , prolonged cranking to start is one of the symptoms of a bad relay and since you have no start at all it would indicate that either BOTH your oil pressure switch AND your relay are non functional (possible) , or , the fender mounted fuse is not supplying power to the circuit . I mentioned the fender mounted fuse in my last post and you again mention the relay , proper troubleshooting of this circuit demands that you check that fuse first , it is the common link between both the relay and the oil pressure switches' ability to run the pump .

Are you at all handy with a voltmeter ? if so the orange wire at the relay should be +12V , which will let you know whether the fuse is actually good or not . The fuse "inline fuse 2 , 20amp" is the one your looking for and I think it's the same for both TBI and TPI (I only have the TPI drawing but I think the fuel pump wiring is the same for both)

 

Awesome! Great informtion and really appreciate it! Where exactly is this inline fuse mounted on the fender? I thought before you were talking about the fuel pump relay.

And yes sir, definitely know how to use a voltmeter. I'll go out today and work on it and check the voltage and let you know what I find out.

 

I have power when turning it over from the relay to the orange wire. Have not found the fusible link yet. Must be on the firewall near the transmission housing.

 

Hey OrangeBird, she's running and went for a test drive without a hiccup. The inline 20amp fuse that was next to the battery was the corrupt. After figuring out where the fuel relay was and tracing the orange wire from there I couldn't find the fusible link to the oil pressure switch but I wonder what caused it to blow?

 

Hi Jim , sorry it took me a while to get back to you , and I'm glad you found the fender mounted fuse . As to why it blew , it would be best to check the wiring for places where it may be rubbing against the body and wearing off the insulation . The wires going into the tank may be suspect , are they pinched between the tank & body anywhere ? Other considerations are , has anyone done any kinds of aftermarket stereo/alarm/etc installation ? Many times improperly wired accessories end up being the culprit for mysteriously blowing fuses . sometimes (crazy rare but it does happen) the fuse itself gets weak from being infiltrated by moisture and opens at less than rated current , but if it's replacement also blows then there is an excessive draw somewhere . Also don't discount the possibility that the pump itself could be going bad and drawing excessive current , even brand new parts fail early sometimes .

Now , as to your oil pressure switch , there were two different types of systems used , one that had two sending units (one each for the gauge and the pump) and the other type had just one sending unit with 3 wires that controlled both the gauge and the pump . Many times when installing aftermarket gauges people who don't understand the system will remove the original sending unit(s) to plumb in the aftermarket gauge and unknowingly disable one of the pump's two means of getting power . If per chance your car does have an aftermarket oil pressure gauge it's possible the wire that is supposed to go to the original sending unit may have been left lying around the engine bay somewhere and could be intermittently shorting out against some of the metal under there .