only starts when FLOORED!!

[kensz28]

O.K. so it's been a while sine my last visit here. Been busy and the cars been runnin fine. Until today. When it first started it surged a few times and when I pulled out of the house it acted like a fuel issue (i.e. NO GAS) Anyway it ran rough a bit then died. It only starts when you keep it floored. I checked fuel pressure and it on the money. Not bad for a stock 15 yr old pump!!!! Anyway once it starts if you unhook the MASS AIR it runs better, if you plug it back it goes to crap again. It will not start normally either way. Gotta keep 'er mashed. WTF? Any ideas? 1995 Roadmaster, .030 LT1, alum heads, SLP headers, intake, basic bolt on stuff.

[93TransAm]

check the MAP sensor as well. if the vehicles sensors arent able to use eachother you wont be able to start. and if it does it will do what feels like run on and stall soft. this is obd2? if so just scan it. if its obd1 unhooking the sensor you believe is the culprit (maf and map) do this and check back.

[kensz28]

Well, I think it's fixed. I tried to start it with mass hooked up and unhooked it made no difference. It actually ran worse with it unplugged. So it wasn't the problem. The only thing I can figure is vapor lock. I was pulling up a hill and I was real low on gas. But a few days later it drove to gas station a mile away no problem and has been fine ever since! Thanks for the reply man.