Rough Idle and Check engine light

[GasDrinker]

i have a 88 bronco ii and have owned for about a month. it has a rebuilt motor and trans with about 5,000miles on each. Within the first week had to replace the fuel pump and along with that replaced fuel filter. Started idling rough after that along with the check engine light (acts like it might die sometimes but never has) Changed sparks plugs but made no difference. it also seems as if the gas mileage is poor now, if someone can please help me with some ideas of whats going on that would be great. i have to drive this to dallas (2hrs away) in a week and don't want it shitting the bed on me half way there, thanks!

 

[RustedRanger]

Go to the Tech section and find out how to check the codes,if the light comes on when it almost dies it should tell you the code for what's wrong. Also unhook the battery for awhile after making changes to reset the ECM.

 

[RonD]

The fuel regulator should have a vacuum line connected to it, remove this line and check it for gas smell or gas, it shouldn't smell like gas, if it does then diaphragm in regulator is leaking.

Fuel return line is import as well, if it gets plugged fuel pressure is high so injectors output more fuel than ECM plans for, so runs rich all the time.


Also check for a vacuum leak in general, spray some quick start or carb cleaner around vacuum hoses, with engine idling, even a small leak can cause rough idle.
With the age of the vehicle cracked vacuum lines would be expected.

yes, getting the code would be helpful to you, some auto parts stores will do it for free.

 

[chillidog10129]

Check the Codes. Could be the o2 sensor or the engine coolant temp sensor(just a hip shot guess) but most important check the codes

 

[GasDrinker]

checked the codes

i checked the codes and one was o2 rich so i checked them out and the one on the manifold has a broke off connection and cannot find the wire to connect it back. where does it run?