Hard starting when hot

[BlueTahoe]

Ok. I know it isn't a truck but I have been fighting this since last summer. It is an 87 celebrity 2.5 litre TBI. Runs perfect. When it is hot out and I stop and run in stores it doesn't want to start. Usually it will start - die immediatly then won't refire. Sometime if I crank for 20-30 seconds it will fire but will spit and sputter for a 10-15 seconds. Then it is back to running perfect. Been 3-4 times were I had to let it sit for 30-45 minutes before it would start.

 

I was suspecting vapor lock type problem and changed the fuel filter assuming this might be clogged limiting pressure and it couldn't push the vapor thru. This did help. It has not left me sitting like it was before but if I try to restart before 30-40 minutes have passed it cranks - dies then crank for 20-30 seconds before it starts again.

 

I have now started cycling the key off and on 5-6 times after it dies and before I try re-cranking. This seems to help it start better. I'm just stumped I keep thinking fuel pump but I would have expected it to fail by now. It has be 20-30K miles since the condition started.

 

FYI once the outside temp drops below about 70 degrees there are no problems at all. Oh and it doesn't matter how much fuel is in the tank. At first I thought maybe the tank was low allowing the pump to heat up but it will do it with a full tank of gas too.

 

Sorry kind of long winded tonght. Any help is appreciated.