Well lately I have been having this hard starting issue. Its been pretty darn hot around here too. The only thing I have done different is use premium gas instead of the low grade stuff. Could the premium cause a hard start issue with these Jeeps? I know I read that these jeeps run their best on the lower grade stuff, is that the case?

 

I put the cheapest gas I can find in mine :P Makes up for the Shell V-Power I use exclusively in the BMW :|

 

High octane fuel doesn't burn with more punch. The octane value is indicative of how hard it is to make the fuel burn, so a higher octane fuel is less prone to detonation in a high-compression motor because it takes more oomph to make it burn. Whereas a lower octane fuel in a high compression motor will cause detonation because the heat and pressure alone can cause it to burn before the spark is introduced.

Try running a lower octane and see what happens. All your doing running high test in a stock Cherokee is burning money.

 

I sometimes run mid-grade in my 91 XJ. I usually run it with Lucas fuel cleaner to clean the system out. As for regular everyday gas, I use 87 grade and get my best mileage with it.

 

.... uh ok, are you saying... yes the higher octane could be causing hard starts? I think thats what you are saying...lol Sorry that went a little over my head but after a couple of re-reads it started sinking in. I did not notice this issue until I put the higher octane in this week. I am still sitting on almost a full tank so I gotta burn this off. It runs and idles pretty good on the higher octane it just starts a little harder.
BTW... this is the first time I used the high octane... I only use the cheap stuff and I just wanted to see how the jeep would run on it.

 

Yeah, pretty much.

 

Very well said, I've been preaching that same thing for years. Unless the owners manual (the book in the glove box) states that you must use a higher octane fuel, run the cheap stuff and save some money.

 

The owner's manual recommends not using higher octane fuel. I don't remember exactly what it says, but I think it states something like it can hurt the performance.

 

I agree with that completely. Higher octane fuel in a low compression engine is just a waste of money and I think it could cause a harder start than normal in some situations.
Clint