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Jeep not starting please help a noob out!

4479 Views 46 Replies 14 Participants Last post by  Nejeep
Hey Guys and Gals,

I recently bought a 2007 Jeep Grand Cherokee with a 3.7L engine on it. I haven't heard great things about these engines but it was a really good price and the car was well taken care of.

Well, it was running perfectly until one morning it just cranked, and cranked and cranked but would not start. I scanned for any codes, nothing. I did some research and found that either the crank or cam shaft positions sensors go bad and won't let them start. Well I went and bought both, oem from dealer. Still nothing. I double checked the fuel pump and you can definitely hear it priming. I even sprayed some fuel starter in the intake and cranked and nothing. That makes me think there is no spark?? I took the valve covers off and checked the timing and it's perfect. No broken tensioners either. I even had a second pair of eyes to check the timing and it was spot on.

What else can it be? I feel lost without codes. I would like to avoid taking to the dealer because I just got married and I don't have much money to spend at the moment.

Thanks in advance.
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You can pull out a spark plug or use a spare plug to test for spark. What kind of code reader are you using? I'll have to admit that I don't know anything about the 3.7 but you'll definitely need to verify that it's getting air, fuel, and spark.
 

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Discussion Starter · #3 ·
You can pull out a spark plug or use a spare plug to test for spark. What kind of code reader are you using? I'll have to admit that I don't know anything about the 3.7 but you'll definitely need to verify that it's getting air, fuel, and spark.
I know it's getting fuel and air, i'll verify the spark tomorrow. I am using a cheap code reader, I know it works because I tested it on my dad's truck that has a light on.
 

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Discussion Starter · #4 ·
So I popped the coil out and put a spark in a cranked it up. Didn’t see any spark at all.

New cam sensor
New crank sensor
Timing chain checked and everything good
All fuses and relays checked

What else could it be? Ignition switch?
 

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Discussion Starter · #6 ·
It does not have remote start, and I actually forgot to ground the spark, all 6 coils were sparking. I checked the plugs and they were all wet and smelled like gas. Really don’t know what else to check
 

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do you have a scanner or a low end code reader?
You have a good spark all 6..... is that the latest?

Anyway no starts are always BASICS

The codes post them ? If unsure of dads scanner; try the key trick...
With KOEO is there 12v at coils?
With KOEO is there 12v at injectors?
Then fuel pressure with a gauge.


We should not have a flooding issue yet, BUT to be sure check the engine oil for evidance of fuel...... A loaded cylinder (fuel load) will cause a surge and hestitation when cranking...
 

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It does not have remote start, and I actually forgot to ground the spark, all 6 coils were sparking. I checked the plugs and they were all wet and smelled like gas. Really don't know what else to check
So you have confirmed spark!

How old are the plugs, could it be that simple?

I would suggest getting the gas out of the cylinders by pulling all the plugs, disconnecting the fuel pump relay, and cranking the engine at least one revolution. That should spit any gasoline out of the cylinders.

Can you confirm fuel pressure with a gauge? - pump can be priming without providing sufficient pressure.
 

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Discussion Starter · #10 ·
do you have a scanner or a low end code reader?
You have a good spark all 6..... is that the latest?

Anyway no starts are always BASICS

The codes post them ? If unsure of dads scanner; try the key trick...
With KOEO is there 12v at coils?
With KOEO is there 12v at injectors?
Then fuel pressure with a gauge.

We should not have a flooding issue yet, BUT to be sure check the engine oil for evidance of fuel...... A loaded cylinder (fuel load) will cause a surge and hestitation when cranking...
It does not have remote start, and I actually forgot to ground the spark, all 6 coils were sparking. I checked the plugs and they were all wet and smelled like gas. Really don't know what else to check
So you have confirmed spark!

How old are the plugs, could it be that simple?

I would suggest getting the gas out of the cylinders by pulling all the plugs, disconnecting the fuel pump relay, and cranking the engine at least one revolution. That should spit any gasoline out of the cylinders.

Can you confirm fuel pressure with a gauge? - pump can be priming without providing sufficient pressure.
Yes, I have confirmed all 6 plugs spark!

I took the plugs out and disconnected the fuel pump relay and cranked it to let the fuel out. Really strong fuel smell came out. I'm gonna leave it alone for a bit to let it dry some more.
Plugs don't look that bad, I feel like bad plugs would cause rough idle and not no start

I don't have a fuel gage, is that something I could rent at a tool store? Should I also check cylinder compression?
 

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you removed plugs SO I recommend hew plugs - only use correct plug!

Fuel pressure test sometimes easier said than done if not familiar. And yes they are often loaners or rentals.

Compression on the list but I think we are still on basics...
Have you tried having a helper try to start as you spray carb cleaner into TB?
 

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you removed plugs SO I recommend hew plugs - only use correct plug!
Fuel pressure test sometimes easier said than done if not familiar. And yes they are often loaners or rentals.
...and gap each one. Do not trust the (well-meaning, but misguided) advice that the plugs are gapped during manufacturing. :nono: They get mishandled and jostled during shipping. On my 5.7L HEMI, at least 65% of the new plugs are not correct; [I've put in 16 spark plugs every 30,000 miles and the Heep has 177,000 miles on it now.]

Check your fuel rail for a Schrader valve where the pressure test gauge can easily connect. Unfortunately, it was eliminated on the '08 HEMI's, but you might have it on your engine. [I'm not familiar with the details of the 3.7L engine hardware.]

Recommend you do a search on this forum for the WK shop manual to download. Can also get the parts manual at: http://wkjeeps.com/misc/Parts/2008_wk_parts.pdf
Owner's manual located at same site.

Hope this helps.
 

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Discussion Starter · #13 ·
you removed plugs SO I recommend hew plugs - only use correct plug!

Fuel pressure test sometimes easier said than done if not familiar. And yes they are often loaners or rentals.

Compression on the list but I think we are still on basics...
Have you tried having a helper try to start as you spray carb cleaner into TB?
Okay I'll get some new plugs, I'll try the carb cleaner thing, first thing in the morning. Would a can of fuel starter work?
 

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If you haven't gotten a pop or bang from the fuel already being dumped in then I doubt starter fluid is going to do much. If you've got fuel, spark, compression, and mechanical timing then my guess would be the electronic timing has something up with it and the plugs are being told to fire at the wrong time.
 

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Discussion Starter · #15 ·
If you haven't gotten a pop or bang from the fuel already being dumped in then I doubt starter fluid is going to do much. If you've got fuel, spark, compression, and mechanical timing then my guess would be the electronic timing has something up with it and the plugs are being told to fire at the wrong time.
What should i check for electronic timing?
 

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timing is computer controlled, set and not adjustable.

Continue with BASICS,

Ignition - spark at several plugs.
Fuel pressure.

The starter fluid is ok NOT my favorite I consider it to volatile.

have you tried key trick for getting codes?
 

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Discussion Starter · #18 ·
timing is computer controlled, set and not adjustable.

Continue with BASICS,

Ignition - spark at several plugs.
Fuel pressure.

The starter fluid is ok NOT my favorite I
consider it to volatile.

have you tried key trick for getting codes?
Yeah I tried the key thing and no codes. I'll check fuel pressure when I get a chance. Low fuel pressure would usually mean bad pump correct?
 

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Yeah I tried the key thing and no codes. I'll check fuel pressure when I get a chance. Low fuel pressure would usually mean bad pump correct?
Most likely. It could be a bad fuel pump, bad fuel regulator, etc. When I purchased my fuel pump for the 4.7L it included, all in one assembly, the fuel filter, fuel pump, and fuel regulator.
 
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