What is this 9th injector or starting injector that I have seen in a few posts. I have a '91 Formula 350 TPI. Do I have one. My car has been hard to start lately. It takes lots of cranking, but once it running it runs great. Changed fuel filter and have 41psi for ignition on and 36-38psi with engine running at idle. I wonder how to check this 9th injector if I even have one. Also any suggestions for other causes of the hard starting? Thanks.

 

The 9th injector was used up until 88-89 didn't have it. It's used for cold starting(enriches the mixture).
Your hard starting could be a few things--checked the fuel pump? You might have dirty injectors too.

 

How are you starting it? Do you go right from "off" to "crank"? Try going from "off" to "on" (aka "test dash lights" position), wait a few seconds until the pump shuts off, then go from "on" to "crank".


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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I have tried going from off to run and listen for the fuel pump to run for the 2 seconds, then crank and it doesn't seem to help. I have even tried going from off to run, off to run several times to make sure the system is "charged." Some people I have talked to say that 36 psi is too low for fuel pressure at the Schrader valve. Does going from 36 psi to something like 42psi make that much difference in starting the engine?

 

Oh, okay, sometimes people just jump the key. Heck I forget sometimes; my car just cranks & cranks & cranks... this usually happens when a hot chick walks by. (sigh)

If the pump is failing, besides not giving the correct pressure, it might not be flowing enough, either. There's a test for that.. you remove the fuel feed line (to the regulator), point the thing in a bucket, and hot-wire the fuel pump test terminal. Then, after 5 minutes, you unhook the test terminal, and measure how much gas the pump pump'd. I don't know how much that is, though...


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I will have to try the flow test, I haven't done that yet. My Hayes service manual (its not very good, but it better than nothing...today I ordered one from Helm..$90..lots of money, but I figure worth it when I have a problem like this!) says to supply 12 Volts to the G pin on the ALDL (lower Left pin) My car doesn't have a pin in that slot. Is there another place to supply 12 Volts other than at the fuel pump harness? Thanks for the help.

 

Yep, there is; but I've got an '86 car, I believe the relays & their locations changed. If wire colors stayed the same, maybe this message of mine can help you (v8 TPI vs v6 TPI fuel pump wiring was the same in '86, I assume it was the same in '91 as well.) https://www.thirdgen.org/messgboard/...ML/000842.html I believe you'd want to give CKT 120 the 12 volts. The Helms book would tell you for sure... and the guys on the TPI message board could, too.




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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Thanks for the help. Electircal wiring in these or any of the cars with EFI is sure a pain! One little $.20 connector or wire can completely disable the vehicle. Oh well, guess a guy has to get used to it. Thanks again.