STUPID JEEP
CF Veteran


Joined: Jun 2011
Posts: 2,720
Likes: 44
From: Gainesville GA
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
CF Veteran
Joined: Jan 2012
Posts: 1,130
Likes: 0
From: Ramona ca
Year: 1990
Model: Cherokee
Engine: 4.0
Came home jeep starts I have spark. It seems like I Dont Know if it's the water issue or temperature issue but one of those is causing her to not send fire into the holes
If it doesn't fire when it's damp out, something is getting moist and causing the ignition system to too weak. Electricity takes the path of least resistance and moisture forms a nice bridge to ground.
Here's another thing you could do. Pick up a in line "spark checker". It plugs in line inbetween a plug wire lead and the spark plug head. Do this in a somewhat darker area. Have an assistant crank the engine when it's dry out. You should have a nice hot blue spark visible in the sight glass. And I'm willing to bet that when you perform this same test when it's damp, some where amongst the coil to one or all of the plugs will show a weak orange spark in the sight glass.
Other than that, are you sure you have the right plugs? Gapped them correctly? And have the correct firing order. Did you buy a set a Duracrap wires and rotor Autozone?
Here's another thing you could do. Pick up a in line "spark checker". It plugs in line inbetween a plug wire lead and the spark plug head. Do this in a somewhat darker area. Have an assistant crank the engine when it's dry out. You should have a nice hot blue spark visible in the sight glass. And I'm willing to bet that when you perform this same test when it's damp, some where amongst the coil to one or all of the plugs will show a weak orange spark in the sight glass.
Other than that, are you sure you have the right plugs? Gapped them correctly? And have the correct firing order. Did you buy a set a Duracrap wires and rotor Autozone?
Seasoned Member
Joined: Jun 2011
Posts: 281
Likes: 0
From: north, ga
Year: 1995
Model: Cherokee
Engine: 4.0
If it doesn't fire when it's damp out, something is getting moist and causing the ignition system to too weak. Electricity takes the path of least resistance and moisture forms a nice bridge to ground.
Here's another thing you could do. Pick up a in line "spark checker". It plugs in line inbetween a plug wire lead and the spark plug head. Do this in a somewhat darker area. Have an assistant crank the engine when it's dry out. You should have a nice hot blue spark visible in the sight glass. And I'm willing to bet that when you perform this same test when it's damp, some where amongst the coil to one or all of the plugs will show a weak orange spark in the sight glass.
Other than that, are you sure you have the right plugs? Gapped them correctly? And have the correct firing order. Did you buy a set a Duracrap wires and rotor Autozone?
Here's another thing you could do. Pick up a in line "spark checker". It plugs in line inbetween a plug wire lead and the spark plug head. Do this in a somewhat darker area. Have an assistant crank the engine when it's dry out. You should have a nice hot blue spark visible in the sight glass. And I'm willing to bet that when you perform this same test when it's damp, some where amongst the coil to one or all of the plugs will show a weak orange spark in the sight glass.
Other than that, are you sure you have the right plugs? Gapped them correctly? And have the correct firing order. Did you buy a set a Duracrap wires and rotor Autozone?
Thread Starter
CF Veteran
Joined: Jan 2012
Posts: 1,130
Likes: 0
From: Ramona ca
Year: 1990
Model: Cherokee
Engine: 4.0
I have the copper plugs for the jeep and all that is golden it started this morning and ran fine nothing under the hood is wet and nopthing undwer the dash is wet so i dont think its a water issue i think its a temp issue when it gets cold out something in the ignition ssytem stops worki ng for a while
Climate change??? 
Anyway, just the slightest bit of moisture (ie condensation) is all it takes. Like dried up long before you started it last night and for sure dried out the rest as it warmed up.
I'm telling ya, this is a classic case. Long before OBD was fart whistle in the wind, ignition systems behaved just the same. Unless you're saying on a "cold" (lol) DRY day it does the same, I stand by my prognosis.
Thread Starter
CF Veteran
Joined: Jan 2012
Posts: 1,130
Likes: 0
From: Ramona ca
Year: 1990
Model: Cherokee
Engine: 4.0
Yes on a cold dry day I would do the same thing earlier this year when I first got it it was doing the same thing. The only thing not new in the ignitionsystem is the coil
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