okay so its getting chilly and naturally my truck has decided to get sick, when i start the truck it idles fine but after driving it awhile, when i come to a stop the idle surges, goes up to about 1100 then down to seven, its not doing this all the time and the TPS was new 4 years ago which was the issue the last time this happened, (its just me but i figured the TPS should last longer than that) only when the tps needed to be replaced, the surging was more prominent from 1200 down to 400 and occured immediately after the trucks warm up cycle completed what do you guys think? fuel pressure regulator? or could it be the cheap Taiwanese advanced auto TPS?, i would check the fuel pressure but unfortunately i dont have a pressure tester for it,
could it also be the front fuel pump? it is a scrap yard pump
umm other problems im haveing are some nut job decided it would be a good idea to cut the inner rubber tube on the filler neck to get the gas tank out and i think the vent valve night be stuck or clogged which is causeing the gas pumps to shut off after only about 2 bucks go in and it continues shutting the pump of after every few bucks causeing me to have to stand outside for about a half an hour just to put a half tank in and sometimes it will up chuck fuel at me if i fill it to fast, just throwing that out there in case it has something to do with it, dunno what else it could be distributor was rebuilt a year ago new coil and plug wires plugs need to be replaced theyve been in there awhile the fuel filter could use stand to be replaced too, the in tank pump is new, no leaky fuel lines air filter was new in july as far as i know the vacuum lines are all okay but ill run through them as soon as i can i guess it could be the map sensor too, i have a spare so ill hook it up and see if the problem goes away, but other than that im lost, i dont have any trouble lights like i did with the TPS sensor (last time it happened) so any ideas?

 

Codes? There are a host of possibilities including the TPS but fault Codes will keep you from chasing all of them blindly.

 

i know i know, but there are none the check engine light is off which is why im thinking its the pressure regulator going out, i dont believe its electronically controlled.

 

Warm the engine up. Check KOEO, CM, KOER. The Continuous Memory may give you the historical issues.

 

Just because the CEL isn't on doesn't mean there aren't any stored codes.

A dying FPR typically manifests by allowing fuel into the vacuum diaphragm.

 

Havent checked for codes yet ill probably get to that tomorrow, but i did change the fuel pressure regulator and the fuel filter, and the surging improved very much, its non existent at star up, after traveling for a few and coming to a stop light itll surge for a second and then smooth out
like i said im checking the computer for stored codes tomorrow, but im almost willing to bet that once i fix the gas tanks venting issues itll solve the problem.