1991 Ford F-350 runs rough at cold start, dies if gas peddle depressed?

SOURCE: when cold, it idles rough, revs high then low! After warmed up it runs fine

if it runs high when you first start it then mellows out,, theirs no problem , all of our chevys do that.... but if its sputtering or you hear a quiet popping noise check spark plugs

Dennis Mulford

• 1055 Answers
• Posted on Jun 11, 2009

SOURCE: 1991 corvette-engine runs rough then cuts off

could be vapor locking, losen up the fuel cap and see if that helps if so then replace it!!!!!!
and chane the fuel filter also

SOURCE: 1995 Chevy silverado with a

I have experienced this problem on similar vehicles. You should try and replace the coolant temp sensor. If it is not reading the correct temp to the ecm, it will not get the right fuel map. Also, the cts will not always throw a code.

SOURCE: Choke Light rough idle

adjust your carb, the 2 screws on each side of the carb adjust so you can get the car to idle correctly, also check your distributor

Harvey N Tawatao

• 3854 Answers
• Posted on Jun 23, 2009

SOURCE: I have an 1989 chevy

It sounds like you may have a bad fuel pressure regulator. The fuel pressure regulator is in the throttle body housing and the throttle body in your truck works best at 13psi to 15psi, Any other setting will cause problems. Check the vacuum hose to the fuel pressure regulator at the throttle body and check the fuel pressure at the shredder valve. The way the throttle body works is for the first 75% of the throttle, the ecm uses the signal form the O2 sensors to control the air fuel ratio and tries to keep it to 14.7:1 but at full throttle it by pass the O2 sensor signal and runs the engine richer and advances the timing so you can drive with wings like red bull. The Map sensor then takes over to promote the engine to run richer so you don't run lean and detonation occurs. If there is a problem with your throttle body position sensor, map sensor. and fuel pressure regulator, then at WOT (skinny peddle down) you may be running to rich. The other thing to is if your fuel pressure drops at WOT you'll get a lean condition and then you'll have detonation ( Knocking) and the timing will be turned down to keep detonation from occurring again and that may be the cause if your check engine light too. First and easiest thing to do is change the fuel filter and add fuel injector cleaner to you gas tank, buy a throttle body cleaner and clean your throttle body to make sure you don't have varnish build up around the throttle body, just follow the instruction on the can. Throttle body cleaner not carb cleaner. Start with that and i hope we don't have to do any more to get your truck running like a rocket. Good luck and keep me posted. Be glad to help.