zoom63

My 98 Cherokee ran fine. Went to start it one morning, and it would crank but not fire. Tried again the next day, and it fired right up, and ran fine until it did the same thing two days later. Also noticed the volt gauge would occasionally peg out driving down the road and then return to normal 14 volts. Don't think its related, but looking for opinions. Thanks for any help.

tjwalker

1. Might be related. Always start with the basics and when that comes to electronics, that means "grounds". I'd freshen grounds and then see where you are at. How to do that shown below.

2. If you have ever seen a check engine light, retrieve codes and post the exact code here for comment.

3. When it cranks and doesn't fire, test for spark. Pull a plug, keep it attached to the plug wire. Have a buddy crank the engine over while you watch for spark. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white indicates a weak spark which may not be strong enough to start the engine (for weak spark, suspect your ignition coil).

4. One more thing; when was the last time you replaced plugs, plug wires, distributor cap and rotor? Tuneup parts very important.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.