So i have a 91 jeep cherokee, just hit 250K miles recently.
Im having an issue where sometimes my jeep starts to misfire and i have no power. its done this 3 times now, all after ive put a pretty decent load on it driving off road AND after its been idleing for a little while.
my temp seems to be about the 210 mark while its doing this.
and i dont know if this has anything to do with this problem but my voltage seems to be dropping at times as well, i was thinking that my alternator is just getting weak.
any ideas, ive been leaning towards fuel pump or 02 sensor but i dont want to spend any more money than i have to. like i said its a 91 with 250,000 miles.

 

1. Gotta be sure your electrical is up to snuff first. At idle, you should see approximately 13.5 to 14.0 volts either at the voltage gauge on the dash or with a meter measuring it at the battery. Be sure you are in this range.

2. As a matter of course, be sure tuneup hardware is fresh. Champion copper plugs, plug wires, distributor cap, rotor, fuel filter, air filter. The importance of tuneup hardware cannot be overstated.

3. Your fuel delivery can be verified quite easily with a simple fuel pressure gauge, which you can rent from many parts stores. At idle, you should have 31 psi. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Be sure that the vacuum line is pulling good vacuum and is in good condition, especially where it connects which is a common point of cracking. If there is fuel in that line, you have a ruptured fuel pressure regulator.

 

well i did a full tune up today and my start up is alot better because it started to missing at start up as well. but still missing at 210. my voltage is just fine.

i havent checked the fuel rail still though.

i just went out and checked my codes and im getting i think a 12, 62, and 55. i dont know what they are, i will be researching them to try and find out.

 

I had a problem like that about 3 years ago. Jeep ran like crap misfiring,smoking especially when cold. I replaced the battery and vehicle ran great.Never had a problem starting and volt gauge never read that it was not charging before I replaced the battery.