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Will not start.

DM_MKV

NAXJA Forum User
Location
Albuquerque N.M.
well guys jeep took a dump
frown.gif


Symptoms:

Wont start. Turns over fine just cranks.. When it happend I had just started motor cool, and it would start hesitating, like a misfire if i gave it gas it would want to die. If i held in the clutch it would rev up as soon as I pressed the gas it would want to die. then hit a stop light and boom died and would not start. Tried to start at home after it was cool and still nothing. Earlier in the day got a CEL got scanned it and p0171 came up for an o2 sensor.. Well investigated a little more and found a crack in the header. Dont think this has anything to do with it but thought I would through it in. Just seeing what you guys would recommend to check.

-Fuel filter is brand new.
-Fuel pump primes.. HOEVER SOUNDS A TAD DIFFERENT WHEN PRIMING..
-Spark plugs, distributor cap, and rotor are all brand new. Checked plugs and cap no burn marks and gets spark.
-Lights work.


Sorry if this sounds noobish but that is because I am
surrender.gif


Theory: Heat form the crack in the headers possibly melted an injector??

As of right now will not start. :loveu:
 
it always helps to list the year and other vehicle specs.

is it a blue snapping spark?
best to test fuel pressure with a gauge, but does fuel spray out of the shrader valve on the fuel rail after you prime the pump?
 
it always helps to list the year and other vehicle specs.

is it a blue snapping spark?
best to test fuel pressure with a gauge, but does fuel spray out of the shrader valve on the fuel rail after you prime the pump?


Doh! It is a 96 4.0. As far as engine goes there is no other modifications dead stock. I did recently change the serpentine belt and alternator both brand new.

Yes blue snapping spark.
 
Doh! It is a 96 4.0. As far as engine goes there is no other modifications dead stock. I did recently change the serpentine belt and alternator both brand new.

Yes blue snapping spark.

how about fuel pressure? just because you hear the pump doesnt mean its pumping the correct/enough pressure.
 
how about fuel pressure? just because you hear the pump doesnt mean its pumping the correct/enough pressure.

Perfect place to start.

Fuel, air, compression, spark, each in the correct amount at the correct time. Determine the missing element.

Fuel: you need the correct pressure, correct volume, and an injector firing pulse to get fuel into the cylinders.
 
hahah to bad I did that with the 99 I had. I want to keep this one.
I am trying to get my hands on something to test the fuel pressure.

I picked up a fuel pressure gauge from Advance auto for something like $40. It's pretty handy on any MPFI vehicle.

I think Autozone lends one out but when I called they wanted something like a $160 deposit.. Could have just been that store but it was laughable just the same.
 
Find a rag and a screw driver. Go poke the shreader valve one the fuel after you prime it. No squirt. No fuel pump. Did you try auto zone.?


Did this twice and pressure seems consistent.

Will probably try this little guy: http://www.harborfreight.com/fuel-injection-pump-tester-92699.html tomorrow.

One important thing I forgot to mention is that since I have had it, it rarely starts on the first try i have to crank it once then let off and crank it again and it starts right up...

Maybe crankshaft position sensor?
 
Did this twice and pressure seems consistent.

Will probably try this little guy: http://www.harborfreight.com/fuel-injection-pump-tester-92699.html tomorrow.

One important thing I forgot to mention is that since I have had it, it rarely starts on the first try i have to crank it once then let off and crank it again and it starts right up...

Maybe crankshaft position sensor?

Third time is a charm.. Tried this again and nothing no fuel even coming out. Tried to prime a few times and if any fuel comes out it is slow drip of a few drops..

Fuel pump? fuel pressure regulator? Fuel relay?

Thank you again for the help.
 
its not the relay if you hear the pump.

regualtor usually will lower pressure, not cut off all pressure.


Cool thanks. Still waiting to get a pressure gauge. I did get a scanner and a new code came on. p0118 After doing some research It says could cause "No Start Condition" I am going to test the ohms today and hopefully my pressure gauge will be in the mail when I get home. Has anyone heard of the CTS causing a jeep not to start?
 
Cool thanks. Still waiting to get a pressure gauge. I did get a scanner and a new code came on. p0118 After doing some research It says could cause "No Start Condition" I am going to test the ohms today and hopefully my pressure gauge will be in the mail when I get home. Has anyone heard of the CTS causing a jeep not to start?


cts usually causes a rough start as it floods the engine with fuel.

faulty magnetic pickup inj the distributor can also give poor running condition

no start can be the cps(crank sensor).

a cracked header can also foul things up as it will allow air to be pulled in through the exhaust valves and also let heat out that can affect the cps and its wiring/harness.
 
cts usually causes a rough start as it floods the engine with fuel.

faulty magnetic pickup inj the distributor can also give poor running condition

no start can be the cps(crank sensor).

a cracked header can also foul things up as it will allow air to be pulled in through the exhaust valves and also let heat out that can affect the cps and its wiring/harness.


This is wear I am leaning now. I just unplugged it and plugged it back in and it started up drove around the block and came home shut it off and now it wont start again I think the cps is the culprit. I will fix that and then hopefully find one of these APN headers that everyone talks about for cheap and hopefully start building it back up to greatness:)
 
The crank sensor can be tested for resistance. When it is suspect, you should test it WHEN the vehicle does not start, as testing it when the vehicle is running may be of no value.

If when the vehicle doesn't start and you HAVE a strong, blue, snapping spark, the problem is NOT the crank sensor. If the crank sensor is bad, you won't have any spark.
 
The crank sensor can be tested for resistance. When it is suspect, you should test it WHEN the vehicle does not start, as testing it when the vehicle is running may be of no value.

If when the vehicle doesn't start and you HAVE a strong, blue, snapping spark, the problem is NOT the crank sensor. If the crank sensor is bad, you won't have any spark.


Car would not start so I had to test it with the car off. I had a strong blue spark, snapping but low resistance in the sensor. I changed the sensor and it started right up. So not sure maybe what I am gauging my spark as strong, snapping, and blue is not very good but seemed to fix the issue. Now I just need a header so I don't possibly ruin anything else. Thanks for all the help guys.:worship:
 
In searching all over the net for my own problem, I found some articles saying that the crank sensor malfunctioning can cause the CPS to not let fuel up to the rail.....This may be another example of this strange phenomenom....


I would agree I had zero pressure in the rail so I was thinking something with fuel was the issue until I tested the CPS. As soon as it was installed I tried to start it and fired right up and have pressure in the rail now.
 
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