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AZTechBrian
AZTechBrian, ASE Certified Technician
Category: Jeep
Satisfied Customers: 706
Experience:  Owner
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99 cherokee sport rebuilt block new, plugs,wires cap rotor

Customer Question

99 cherokee sport rebuilt long block new, plugs,wires cap rotor alt, ignition switch, battery, checked spark and injector pulse with noid lite all checks ok. turns over but wont start. open throttleall the way and it acts like it wants to start but doesn't.
double checked no 1 on distributor right on.
Submitted: 1 year ago.
Category: Jeep
Expert:  roybelding replied 1 year ago.

good morning my name is ***** ***** I will assist

can you check the actual fuel pressure??? have you tried spraying carb cleaner into the air filter to see if it starts and stalls out??

Roy

Customer: replied 1 year ago.
fuel pressure is ok .checked with tester gauge. yes tried starter fluid nothing same response.
Expert:  roybelding replied 1 year ago.

ok, then check for spark. did you replace the crank sensor??

Roy

Customer: replied 1 year ago.
have spark. yes changed crank sensor. checked voltage per the book. ok
Expert:  roybelding replied 1 year ago.

ok. try spraying some carb cleaner into the air filter and see if it starts and stalls

Roy

Customer: replied 1 year ago.
did that nothing.
Expert:  AZTechBrian replied 1 year ago.

Hello. If it's ok, I will try to help you. If it' seems like it wants to start with the pedal to the floor, then try removing your fuel pump fuse and attempt to start it. Maybe your getting too much fuel... pegging the gas pedal to the floor cuts off the injectors. Try that first. Next, Have you done a compression test? If you have confirmed that you are in fact getting fuel and you are certain that your getting spark, then we need to know that your compression is good.

Customer: replied 1 year ago.
compression is 135 all 6 cyl .. should the injector have spray when it is triggered or stream of fuel ? I will try the fuse and relay. cant do till sat.
Expert:  AZTechBrian replied 1 year ago.

135 is perfect. The injectors should spray fuel, not squirt a stream. Did you try again today, and it still won't start? I meant to try removing the fuel pump fuse yesterday when it was acting up thinking you possibly had a flooded engine. If it wouldn't start even after sitting for a day, then I doubt that is your problem. You could also remove a plug and crank the motor and see if it smells very strong of gas. quick question though, when you installed your distributor, are you positive that you aligned it for the 4.0? That distributor is the same for the 4 cylinder and the 6 cylinder engines.. The only difference is the alignment when you install it. It has to be aligned correctly for the 4.0, and locked in place before installation. If that's not done correctly then your jeep won't start. If you don't know what I mean, let me know and I will get you a diagram with the alignment instructions.

Customer: replied 1 year ago.
pulled pump relay no difference. yes double checked distributor location. in time. double checking injectors for spray or stream? if they are stream replace?
Expert:  AZTechBrian replied 1 year ago.

Ok. I didn't think pulling the relay would help you at this point. I meant to pull it when you originally posted the question, in case you happened to have a flooded engine. I will add a picture of what the injector spray pattern should look like. If you don't have a good spray pattern you can try cleaning the injectors before you spend the money to replace them. I can find you a video of how to do that if you would like to try that. I am curious, what is your fuel pressure? How did your injector spray pattern look?

Expert:  AZTechBrian replied 1 year ago.

.

Customer: replied 1 year ago.
fuel pressure inspec 50 psi .. put new injector in same pattern not a spray but a full stream at each pulse. like it is calling for to much fuel? what controls the amount of fuel injected?
Expert:  AZTechBrian replied 1 year ago.

the pulse width of your fuel injectors is determined by your ECU. your ECU decides how much fuel to deliver based on the inputs of various sensors.

It's determined by the volume of air taken in by the engine and the engine's rpm. The sensors also provide the ECU with several other data including workload, exhaust gas composition as well as engine and ambient temperatures. All of these data gathered by the ECU sensor determines the amount of fuel needed to be injected and mixed with the incoming air.

Expert:  AZTechBrian replied 1 year ago.

Does it even stumble like it wants to start?

Customer: replied 1 year ago.
at first like it is flooded then nothing.
Expert:  AZTechBrian replied 1 year ago.

Can you disable your fuel pump and try starting it with starter fluid? This way we know if we are barking up the right tree or not. IF you can get it to start even for a short time with the fuel system disabled then we know that we should be looking at a fault with the fuel system. Make sure that the engine is not flooded before attempting this or the outcome will be misleading

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