1987 300. idles eratic. and misses

[jayboy]

ok, so i have a 1987 f150 with a 300. 4spd. at an idle it is eratic. it will rev up and down the entire time. and it almost dies out. i have replaced egr. cleaned the throttle body. also brand new motorcraft plugs. now another problem. the other day i broke the starter relay. so i put one i had laying around on it. worked fine. but now it seems as if it has a dead miss in it. the exausht doesn't smell right. it will burn your eyes. i think its getting to much fuel compared to the oxygen. any ideas?

 

[TexasNomad]

Could be a bad vac leak.

 

[jayboy]

gave it a vac test. its around 20ish.

 

[TexasNomad]

Was the gauge needle bouncing around or flattering?

 

[blacksnapon]

You might get a scanner to get into the data stream so you can look at the coolant temp sensor (too cold and the pcm will richen up the mixture in an attempt to "warm it up"). Fuel pressure regulator, slobbering injector also come to mind.

 

[Watchdog7]

Sounds like you have a floater in your fuel tank. No seriously, someone took a crap in your fuel tank.

Gonna be bad trying to get that one out of there.

 

[jayboy]

at first yes the vac gauge was bouncing around alot. then i reved the engine up for a while and it stopped bouncing around. my dad was a ford mecahnic for thirty years. and he thinks its a vac leak as well. but im thinking its the fpr.

 

[TexasNomad]

It could be that or it could be a mixture of things thats why you have to check every thing, also you might have some junk in your fuel tank, rust in your gas can cause for all kinds of problems and mimic allot of different things.
check your fuel and make sure its clean.

 

[jayboy]

my gas is clean. btw