bakerstreet

I have a 92 rs 305 automatic 191k miles, the car has always run great. The problem is when the car is started from cold it shakes & stumbles & will die if you don't keep pumping on the gas. After it initially warms up, it will still die if you stop pumping the gas pedal, but if you turn off the key & restart it 2 or 3 times it will then idle normally & it then runs great. It also cranks up normally.

It's been doing this no matter if it's 100 degress outside or zero degrees.

If I then drive somewhere & turn it off & then restart it, it then goes thru the same ruff running & stumbling act.

All new plugs & wires, distributer cap & rotor, collant temp sensor, tps, map sensor, iac valve, pvc valve, egr valve (both passages are clear), 02 sensor, fuel filter, & the sensor that's inside of the breather (& it opens & closes normally)

After replacing all of these, i still have the same problem. I have a service manual & i checked all of the sensors b/4 & after replacing & they all tested the same.

No vacum leaks, it doesn't run hot, timing is 0 degrees, & the egr valve is operating properly.



So what do you guys think may be the problem.

ex-x-fire

Unhook the vacuum line to the egr, hook that up to a vacuum gauge & see if you have vacuum on start up. You shouldn't have vacuum their.
Check the fuel pressure, the car may start on low psi but might not run right. Normal fuel press is 9-12 psi.
Check the ecm ground wires on the back of the heads.

89shane350

iTrader: (1)

UPDATE?

GreekItalianMan

Probably running rich at start up. A/F ratio might be messed up, ditto to what ex fire said or it might be your starter under the car. Check it and see if the wire is properly connected.

bakerstreet

Turned out to be the fuel pump, i replaced it & the RS runs like new. This was so strange, i didn't know that fuel pumps would cause these kinds of symptoms.