4.0 ohv runs like crap

[That_4.0_ranger]

my 91 4.0 has developed a very rough surging idle and long crank often time it will fire then die then i have try again also when gets to a 1/4 tank it dies when i come to a stop and the dose not want to start like a solid 1 minute of cranking any ideas?

 

[jballard81]

I'm no expert, but this sounds like it could be a number of things. what tests have you performed?
fuel pressure should be 30-40lbs at idle.
have you changed the fuel filter in recent memory?
any codes when running a key on engine off test?

I'm chasing a poor idle in my 94 and I'm trying to think of some of the trouble shooting i've performed lol...

 

[That_4.0_ranger]

i have a new fuel filter for it that i bought when i got it and its just been sitting on the shelf lol and i have an obd1 code reader i will plug in see what codes i get and how do i check the fuel pressure?

 

[jballard81]

vacuum/fuel tester to check fuel pressure, but a quick and dirty way would be to find the Schrader valve somewhere along the fuel rail on the engine, remove the cap if there is one and depress the middle of it quickly to see if you get a 'good' squirt of fuel out of it.

what's a 'good' squirt? i dunno, that's what the fuel pressure tester would be for LOL.

i would be more interested if it was pressurized before you start it, then again while it's idling, then come back and try again after shutting it down for say 20 min to see if it's holding fuel pressure (if it was pressurized in the beginning, no need to test again now).