I have an 89 RS 305 TBI auto trans. My car has always had a problem where about once a month it would shut off at a stop but it wasnt really a big deal because it would start back up just fine. A couple weeks ago my Ignition control module went out and I replaced it and the distributor cap and rotor. Since then the car wants to shut off every time I shift into reverse or drive unless I give it gas. Its the same problem ive had before just much worse. Just yesterday I replaced the spark plugs, plug wires, coolant temp sensor and the fuel filter and it keeps doing the same thing. Any troubleshooting or common problems would help greatly because this is my daily driver and ive got to go 250 miles on sunday.

 

What’s your fuel pressure at ?

 

I have no way of checking the fuel pressure but could it be something else?

also if it help it shifts just fine between reverse and drive but not from neutral or park to drive or reverse

 

I wouldn’t rule it out, since you went through the ignition system and all is well.

 

I wouldn’t rule it out, since you went through the ignition system and all is well.
Some autoparts stores rent pressure testers and the adapter for the Throttlebody and or fuel filter.

 

Could it have anything to do with the IAC Valve or the TPS?

 

Bold Point 1 - Have you pulled trouble codes? Checked and replaced any/all damaged grounds? (as you mentioned in another thread of yours I believe)

Bold Point 2 - This reminds me of a situation I had that ended up being Fuel Pressure related. Drive/Reverse are higher fuel demand conditions over Park/Neutral.

Bold Point 3 & the above quote - I wouldn't guess, if you have a 250 mi trip to make sunday then you need a systematic approach to troubleshooting. FIRST thing tomorrow morning RENT the FP Test gauge as suggested. Tap either under the hood or at the filter. By almost any means necessary safely measure the fuel pressure while driving about 10ft-15ft maybe 20ft forward or reverse. If pressure drops below 11psi hope for a clogged fuel filter because your heading to pumpsville unless you've got a line leak.

Fuel Pressure can impact O2 voltage & MAP voltage ALL of which will leave you stranded BUT more importantly all of this is ONLY my

 

Thank you for the response. I will try to rent a FP test gauge. At first I thought it was my filter and its been replaced and it hasn't gotten better. I most certainly don’t want to head to pumpsville as ive heard it is incredibly difficult to do. How long should my pump last As far as miles go? I have 170k miles and im pretty sure its original or atleast 15 years old.

I thought it would have something to do with the vacuum or carb but I guess not. I dont really know how to test the fuel pressure for a tbi, does anyone know a forum for it or instructions?

 

My fuel pressure is fine. Out of desperation I unplugged the IAC valve and ran it and it sat a 2k rpms so I know thats not the problem. Then I took out the tps sensor and when I shift everything is really smooth and doesn't shut off but instead sits at 1000 rpms. Could that be a problem? Also what would the voltage need to be for the tps for a 305 tbi

 

Could be, you can do a voltage sweep. The best way is with a analog vom.

 

Ive bought a new TPS. If that doesn't turn out to be the problem would it hurt anything if i were to drive it without the tps in? It seems to run better without it.

 

Now that I think about it, could I have installed my Ignition control module on wrong or not tight enough to get a proper ground? I heard some say that there should be some sort of lubricant below it where it touches the base of the distributor cap. Is this true? And is that the ground location for it?

 

Not sure the ICM can be installed "wrong" all it's connections are different, and they're not supposed to be torqued down to all ****, just snug. You heard correct, there is supposed to be Thermal Paste on the base of the ICM to dissipate heat. The two screws holding the ICM to dizzy base provide the ground so screws and dizzy base need to be clean when installing the ICM.

 

Alright, so far ive replaced
-ICM
-Distributor Cap & Rotor
-Spark Plugs
-Plug Wires
-Coolant temp sensor
-TPS
-EGR Valve
-Fuel Filter
My car still shuts off when I'm at a stop or when I shift into drive or reverse. Im guessing my next step (probably should have done before) is to check the fuel pressure with some sort of fitting I can put between the soft and hard part of my fuel line to see if my pump is going bad?

 

Maybe check the idle air motor/passage for carbon/soot buildup ?

 

Thank you everyone for the help. I finally figured my **** out. The new Ignition Control Module was faulty. It would turn over the car but at low rpms it would die. Wish i figured it out earlier before I did literally everything else on that list to my car. But at-least I got a lot of preventative maintenance done and learned a lot in the process.