Hi have a straight 6 1994 grand Cherokee.Lately when I try to start it,it may not start.It will always crank.Sometimes after a few tries it starts and runs great.Sometimes it won't start.If I try later in the day it might start right up. I'm just afraid the day will come when I get stuck somewhere because it fails to start.The fuel pump was replaced about 5 years ago.But like I say when it does start it runs great.I was thinking maybe fuel pump relay or ignition trouble Anyone ever see something like this? thanks for any help you can give. Alan

 

Fuel pump. Rent a fuel pressure gauge from autozone and test the pressure

 

You need to check and see if it a spark or fuel issue. The easiest way to tell is with a can of starting fluid. The next time it does not want to start spray some starting fluid in the intake, if it fires right up and stalls after a few seconds, you have a fuel problem. If nothing happens, you have no spark. Also, if the battery is low on charge there may be only enough voltage to spin the starter, but not enough for the ignition system or fuel pump to do their jobs while cranking.

 

thats guys I'll try the starting fluid tomorrow .Great idea That will tell if there is spark.Also if they still use a 1/4 flare fitting on the fuel rail ,I'll be able to check fuel pressure,cause I have a gauge with a 1/4 flare fitting/schrader depresser.how much pressure am I hoping to see.Don't forget ,I might just turn the key and it sometimes starts and runs all day like everything is fine.could it still be the fuel pump?that why I was thinking fuel relay.I get back with you guys after work tomorrow thanks for the lead

 

The fuel pressure should be 45-55psi.

 

Hi you guys sure know your jeeps Got it started today Had fuel pressure ,checked it with a gauge then was told that it might be the crank sensor.nearly, $60 so I was a little hesitant to go for it.The more you guys described the symptoms of a failing crank sensor the more it sounded like my problem.What a pain in the butt it was to change. Who ever thought to put it there should be fired.If the auto store didn't let me look at a book to see its location, I'd still be searching for it. Anyway by this time the battery was low,so I had to borrow a charger from a friend. Just went out there ,turned the key and she started and purred You guys DO really know your stuff