98 Xj hard to start.

Sentry87 · Apr 3, 2010

ok so here is the deal. i have a 98 xj 4.0l 4 speed auto, 215k mi. pretty much regardless of what temp the motor is whether it is a cold start or a warm start it takes close to 5-10 seconds for the engine start, and sometimes longer than that. past 2 months i have ran lucas fuel system cleaner throught twice, new plugs, new wires, and went over all the injectors for proper voltage and duration. my best guess would be its either the cap, rotor, or ign. coil. being new to jeeps i just want to be heading in the right direction before i go throwing money at a problem.

birchlakeXJ · Apr 3, 2010

Always, always be sure that your tuneup hardware is fresh before looking elsewhere.

Replace cap, rotor. $15-$20 worth of parts. Your ignition coil can be tested for primary/secondary resistances but I don't think that is your problem.

If it is still symptomatic after changing out cap/rotor, fuel pressure testing WITH A FUEL PRESSURE GAUGE would be a good idea. You're looking for the cause of possible fuel pressure "leakdown" while the engine is not running. That can be anywhere from the gas tank to the injectors.

There are specs about acceptable leakdown rates over time. Consult the factory service manual for detailed information which is very helpful in isolating issues like this.

If the engine is hot and you turn it off, then IMMEDIATELY try to start it, does it still take an extended crank to start the engine??

Try this quick and dirty test when starting a cold engine.

1. Turn key to ON position (do NOT crank the engine)
2. Fuel pump should energize and run for approx. 2 seconds
3. Turn key OFF
4. Repeat 1-3 a couple more times
5. NOW crank the engine

Does it start quicker? If so, that poor mans prime has confirmed a loss of fuel pressure.

joe_peters · Apr 4, 2010

birchlakeXJ said:
Always, always be sure that your tuneup hardware is fresh before looking elsewhere.

Replace cap, rotor. $15-$20 worth of parts. Your ignition coil can be tested for primary/secondary resistances but I don't think that is your problem.

If it is still symptomatic after changing out cap/rotor, fuel pressure testing WITH A FUEL PRESSURE GAUGE would be a good idea. You're looking for the cause of possible fuel pressure "leakdown" while the engine is not running. That can be anywhere from the gas tank to the injectors.

There are specs about acceptable leakdown rates over time. Consult the factory service manual for detailed information which is very helpful in isolating issues like this.

If the engine is hot and you turn it off, then IMMEDIATELY try to start it, does it still take an extended crank to start the engine??

Try this quick and dirty test when starting a cold engine.

1. Turn key to ON position (do NOT crank the engine)
2. Fuel pump should energize and run for approx. 2 seconds
3. Turn key OFF
4. Repeat 1-3 a couple more times
5. NOW crank the engine

Does it start quicker? If so, that poor mans prime has confirmed a loss of fuel pressure.

I agree. The only thing I would add is get the cap and rotor with brass contacts, avoid the aluminum ones.

Jesse714 · Apr 4, 2010

Sometimes a faulty CPS will do it, same as a TPS i suppose.

98 Xj hard to start.

Sentry87

NAXJA Forum User

birchlakeXJ

NAXJA Forum User

joe_peters

NAXJA Forum User

Jesse714

NAXJA Forum User

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