'91 hardbody questions...long

[zm830101]

i am having a little trouble with my hardbody. it is a '91 KA 5 spd 2wd king cab with 189000 miles.

it normally runs great. the only problem being a high fluctuating idle that is intermittent. just recently though it started acting up. when i go to start it i have to be very certain that it catches fire on the first start attempt. if not it fouls the plugs. the only way to start it if i miss on the first try is to pull the plugs and clean the raw fuel off of them or push start it.

then after it is running it idles very low and bogs when you try to give it throttle. the bog is only momentary and after the revs pick up to over 2000 it runs relatively smooth.

i have pulled and cleaned the injectors 'cause i thought at first that they might be hanging open. wires, plugs, distributor cap, rotor are all new as of yesterday. fuel filter is new. i have a new pcv as well as vacuum lines and was going to replace them to see if it cured the high idle issue but that has become a moot point now that it is barely running.

i am suspicious of the EVAP system because the tank always has pressure in it that is released when you take off the gas cap but i don't know if that would cause the troubles i have been having.

anybody know if a hotter plug would help with the fouling issues? got a part #?

any suggestions would be much appreciated

[nismopu]

bad fuel pressure regulator most likely. peace.

[Desert Rat]

The idle and rich issues could be from a vacuum leak someplace. get a can of carb cleaner and with the engine running, start spraying around all vacuum lines and fittings. If you suddenly kill the motor, or if it revs suddenly, you found a leak.

[zm830101]

well, since i originally posted i have replaced almost all vacuum lines as well as the o2 sensor.

randomly today it started perfectly and ran great. went to work parked all day started to go home no problems. parked at home and sat about two hours then had to go to store and damnit if it didn't start acting retarded again. i need a fuel pressure gauge. i wanna see if there was any truth to the thought of it being the FPR. it also occured to me that the pump may be failing

i'll have to try the carb cleaner/propane trick. any more suggestions?

[zm830101]

while i am thinking about it, would a weak battery cause issues like i am having?

[Big-Bird]

The manual for the Hardbody has these items in the troubleshooting guide related to rough or loping idle.

[RT]

Buddy had same issue was fuel regulator

[WWJD]

battery wont cause it.

if you wanna make a quick check on you FPR dissconect the vac. line on it and start her up. If it starts up any better then it's time 4 a new 1

[zm830101]

found the problem a while back so i just thought i would update. was playing around under hood while it was idling one afternoon and mistakenly bumped the injector harness. it immediately settled into a stable idle at a perfect 750 rpm. so i bumped the harness again, and the idle went up and it started hunting again.

through further trial and error i isolated the problem to a tear in the signal wire from the coolant temperature sensor. so i cut out the tear and spliced the wire back together...bingo! not a problem for about the last two weeks my only guess is that the computer, not recognizing a CT sensor on start up, was going into some form of a rich/limp mode sorta deal thus causing the plug fouling on start up.

now that this has been resolve this has been the best hundred dollar truck i ever bought

[rn240sx]

found the problem a while back so i just thought i would update. was playing around under hood while it was idling one afternoon and mistakenly bumped the injector harness. it immediately settled into a stable idle at a perfect 750 rpm. so i bumped the harness again, and the idle went up and it started hunting again.

through further trial and error i isolated the problem to a tear in the signal wire from the coolant temperature sensor. so i cut out the tear and spliced the wire back together...bingo! not a problem for about the last two weeks my only guess is that the computer, not recognizing a CT sensor on start up, was going into some form of a rich/limp mode sorta deal thus causing the plug fouling on start up.

now that this has been resolve this has been the best hundred dollar truck i ever bought

Its funny u mention this cause my buddy has a sohc 90 240sx and everytime he moves that wire harness above the injector rail... the idle goes to crap and sometimes even stalls out..!! My 92 hardbody does the SAME thing... u mess with the harness above the inj rail and idle mess' up and sometimes will stall out...He kept saying it was the coolant temp sensor but never replaced it. He just deals with the issue. Where about on that harness was the break in the wire..?? Im guessing this is somewhat of a common issue amoung the sohc harness'....