Hard Start Issue

PalmettoStateBob

PalmettoStateBob

TJ Enthusiast
Supporting Member
Joined
Apr 14, 2020
Messages
129
Location
Anderson, SC
2000 TJ 4.0
Takes several attempts to start. Tried cycling the switch 5 times for 5 seconds each, still hard start. After starting I backed it out of garage, shut it off, hard start again. Runs fine once started. Also, I let it run 45 minutes, shut it off, now its went from hard start to possibly a no start. Was running good when I shut it off. This is first time I couldn't get it started at all. Suggestions ??
 
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You should be closer to 50 but 45 shouldn't make that near impossible to start.

That said...
Engine light on?

Plugs were last done when?

Do you have A/C? If so what happens if you run A/C at idle. Rpms bounce? Almost stall?

Battery age?

Battery connections?

We just did a tune up on a 4.0 that had plugs from Vietnam era.
20210220_144011.jpg


The two broken weren't broke in the head but the porcelain was extremely brittle.

Whoa...this thing ran better than it has in years.
 
Rubicon88 said:
You should be closer to 50 but 45 shouldn't make that near impossible to start.

That said...
Engine light on?

Plugs were last done when?

Do you have A/C? If so what happens if you run A/C at idle. Rpms bounce? Almost stall?

Battery age?

Battery connections?

We just did a tune up on a 4.0 that had plugs from Vietnam era.
View attachment 227760

The two broken weren't broke in the head but the porcelain was extremely brittle.

Whoa...this thing ran better than it has in years.
Click to expand...
I was just reading up on Cam and Crank sensors. I bought Jeep used last spring. Always cranked and ran well. Had about 3 or 4 random times that it ran rough when I first started it, but would cut it off and it would idle fine on restart. Been a while since that happened. Engine has no Skip to it. Just got hard to start one day and doesn’t matter if it’s cold start or warm start. Battery is older but tests good. Spins over good. I haven’t changed plugs since I’ve had it because it runs well. Pretty good fuel mileage too.
 
Finally got it to start. Pulled it into garage. Cut it off, started it up after slightly hard start. Cut it off, back to no start. It tries to fire every so often but that’s about it. Still no check engine. I will say that there is a very slight miss when running. Didn’t really notice it before, but was looking and listening harder this time. But very slight
 
PalmettoStateBob said:
I was just reading up on Cam and Crank sensors. I bought Jeep used last spring. Always cranked and ran well. Had about 3 or 4 random times that it ran rough when I first started it, but would cut it off and it would idle fine on restart. Been a while since that happened. Engine has no Skip to it. Just got hard to start one day and doesn’t matter if it’s cold start or warm start. Battery is older but tests good. Spins over good. I haven’t changed plugs since I’ve had it because it runs well. Pretty good fuel mileage too.
Click to expand...
Ok...see the above plugs?

This came in for a cylinder 4 misfire. Immediately.

According to the owner it "ran great" before the misfire.
It too would do a hard start. Not always but at different times for no apparent reason. (According to owner.)

After new plug install his response was WOW...this never ran so good. Much better than before to what he thought "ran good".

I'm not saying you've got a plug issue but you've no idea the age, condition, brand etc.
It doesn't take a whole lot to make these simple things run decently.
Moreover for the cost of six ZFR5N (factory recommended NGK plug)
Fresh plugs is never a bad thing and heck...it just might help your problem.

What do you mean battery is older but tests good? How old and how did you test it? You NEED to see the cranking amps of the battery not just 12 volts.
 
Well battery is 5 years old and was going to replace it before getting stranded. Still holds a charge and I tested with volt meter, not a true under load test. But it does turn over quickly. I’m leaning towards a cam or crank sensor. Coil pack is most expensive part, so unless something I find points directly to it, it will be a later option.
 
Put fuel pressure gage back on and it went from 0-45 soon as I turned the switch. Turned engine over and it went to 49. Let it sit a couple hours and it dropped to 20. Going to let it sit over night but expecting 0 tomorrow. But each time I put gage on and turned switch pressure jumped up immediately. Not sure if it's my hard start issue or a separate issue. Fact that pressure jumps up so quick makes me think that hard start is still something else.
 
do you have access to a scan tool that reads live data? if so look at the cam and crank sensor
are they both showing rpm's while cranking? if they are both showing crank rpm, they are fine.
 
PalmettoStateBob said:
Put fuel pressure gage back on and it went from 0-45 soon as I turned the switch. Turned engine over and it went to 49. Let it sit a couple hours and it dropped to 20. Going to let it sit over night but expecting 0 tomorrow. But each time I put gage on and turned switch pressure jumped up immediately. Not sure if it's my hard start issue or a separate issue. Fact that pressure jumps up so quick makes me think that hard start is still something else.
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you are correct. fuel pressure jumping to 49 psi at ignition on is fine.
 
williambmac said:
do you have access to a scan tool that reads live data? if so look at the cam and crank sensor
are they both showing rpm's while cranking? if they are both showing crank rpm, they are fine.
Click to expand...
Neighbor has a code scanner but check engine light has not came on, so don't think it is throwing a code. I'll ask him if it does live data
 
Replaced battery because it was 6 years old. Still hard start, but since it turns over faster it doesn't see to take as long. Ordered plugs from Rock Auto along with Cam Sensor. Will replace plugs first and try again before changing sensor
 
Did needed maintenance. Replaced 6 year old battery, new double platinum plugs. Changed cam sensor. Still a little hard but much better. Will take 2-3 tries of turning engine over about 4 times. Not great but much better
 
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