Hey Ya'll. I know this isn't a dodge question and hell...it's not even about a truck but I've been coming here alot and your all very helpful when I need info for my Dodge Ram. My grandfathers 92 Chevy Lumina 3.1L is having some starting issues. He says it starts like a champ in cold weather but in warm and hot weather it will not start unless he presses the accelerator pedal all the way to the ground. When he does this it fires right up. He does all the basics on it (air filter changes, oil changes) and the battery is good too. His car isn't throwing any codes at all so I'm at a loss. Possibly a dirty sensor somewhere? Maybe the TPS? Any help would be appreciated. Thanks. Keep up the good work here at the forums and I'll try to keep contributing as much as possible. This really is a great group.

 

It could be either a sensor issue, or it could be a fuel/fuel line/fuel pump/vapor lockissue. What kind of setup does it have, tbi or mpi? returned or returnless? Does it have an accumulator?

 

to me it sounds likea vapor lock issue but it could be the fuel pump getting weak you may want to check the fuel pressure it could evean be the fuel pressure regulator.

 

Maybe I'm wrong in my understanding of a vapor lock issue but wouldn't that problem occur when the engine is warm? His problem is occuring when the weather is warm but the engine is cold. I also believe he told me that once his engine warms up then it starts just fine after that ( like if he turned it off then tried to restart it within a half hour or so)

 

Fuel pumps are a common problem with 3.1L Luminas.

 

That is correct. Usually a vapor lock issue affects a hot engine, and after it sits and cools the vapor will work itself out. I guess I missed that in your original post? It still sounds like a fuel system issue because of the thing. It could be the tps, but why that would be affected by ambient temps is beyond me. Have you checked fuel pressure? When, after he fully depresses the throttle in warm/ hot temps, does it sputter upon starting? What about the fuel system setup?

 

sorry I misunderstood that but it could still be the fuel pump due to pressure building in the gas tank I have seen that before.

 

Well there you go. Who says you can't find chevy help on a Dodge forum. Especially when Grandpa's ride is on the line. I wish I still had mine to help out.

 

Have to admit right off that I don't know this engine setup. If it is a throttle body though, there should be some form of idle air bypass valve. What this does is the exact opposite of a choke on a carb. On a carbed engine you push the accelerator pedal to put in a squirt of fuel and set the choke to the closed position. On a throttle body though, you are NOT supposed to touch the pedal. In this setup the intake remains closed exept for a small bypass port that opens to let some air IN. It may be vacuum operated or electric or both. It is responsible for a fast idle at startup too. After a short period of time the valve begins to close (again either vac.or elec. or computer) and the idle drops and off you go. I'd look for such a control on that engine. If you have no manual for that car, try autozone.com and look for repair info. under emissions. Hope this helps.
WC