5.8 overfueling, running rough.

hi guys, i am still working on the truck i did the cab swap on earlier in the year, havnt had alot of time since before xmas, but it is overfueling bad and fouls the plugs up, it was doing this before i switched cabs, i thought a new set of plugs and wires would cure it, but it hasnt, unplugged the oxygen sensor, no difference, no codes coming up, fuel pressure regulator seems to be good, 40-45 lbs.any ideas what else could be doing this. the temp guage doesnt work. could the map sensor be bad and not throw a code? dual tanks and does the same on both tanks. thanks, kyle

Did you pull the vacuum hose off the regulator and make sur that it's not letting gas through it?
And yes the map can go bad and not code up.


Jay

[quote="havinfun"]Did you pull the vacuum hose off the regulator and make sur that it's not letting gas through it?
And yes the map can go bad and not code up.
yes we did test the pressure guage for leakage. would the map sensor make it overfuel?

What I was trying to say is the regulator can go bad and force raw gas through the vacuum hose.
Yes the map can cause it to run rich, unplug it and see if it gets better or worse (i've seen a few that wouldn't
run with it unplugged).
Also make sure the vacuum hose to the map is open also.

i will try those tommorrow nite, i have done some searches and it seems the most common for overfueling is the fuel pressure regulator malfunction, it idles at 35-40 lbs.thanks havinfun. kyle

I have a 86 with the 5.0 (302) when my dad had it it started fouling the plugs he changed map sensor,o2 sensor,plugs,plug wires. to still have the same problem I happen to be over at his house and had a old dizzy out of a 302 with the electronic box on the side of it took it off and put on it and it helped some.So I pulled the coil off mine and put on it and it started running right don't now for sure with it was or both left it on and went to town. We bought a new coil and put back on mine and and it still has both on it that was about 4 years ago.Don't now if that is your problem or not but the spark might not be hot enough and not letting it burn the gas right. Just something you might want to check.

something to consider, i have 2 spare engines for parts, think i will try that if the map sensor swap doesnt work, thank you.