Cherokee kk no start

[Niloc]

Hi
Still got a problem with my 2.8crd kk cranking but not starting.
Initially had crankshaft sensor code but replaced and no difference so tested the existing one and it was fine.
I had the fuel pump checked the wiring checked and the timing checked but no problems with any of those.
My next port of call is if the immobiliser is causing this but I have no idea as how to check or even disable the immobiliser temporarily if necessary.
Has anyone have an idea as to how to check this please.

Thank you
Colin

 

[KJowner]

A few things I suggest you check-

Has it got plenty of fuel in the tank? I believe there is an interlock that prevents fuel pump damage if the ecu sees no fuel.
The crank sensor is OK, so that's good but there is also a cam sensor, if that has failed the engine won't start either.
Glow plugs OK and getting voltage on start up?
And the old favourite is air in the fuel system, have you tried bleeding out the air and getting someone else to try starting the engine as you work the lift pump.

 

[Niloc]

A few things I suggest you check-

Has it got plenty of fuel in the tank? I believe there is an interlock that prevents fuel pump damage if the ecu sees no fuel.
The crank sensor is OK, so that's good but there is also a cam sensor, if that has failed the engine won't start either.
Glow plugs OK and getting voltage on start up?
And the old favourite is air in the fuel system, have you tried bleeding out the air and getting someone else to try starting the engine as you work the lift pump.Hi

Thank you for taking the time to reply and we have covered all the steps your mentioned .
There is 3/4 of a tank of fuel
Cam sensor was replaced as well as crank sensor but both the old units tested good.
Glow plugs are good and getting signal on start.
The garage has replaced fuel pump and bled system and get 4 bar at rail do lift pump working fine as far as I understand it.
There seems to be something fundamental.going on here but failing to find it yet

 

[KJowner]

4 bar is nowhere near enough, the rail should be way more, the system can be upto10,000 psi when running. You have a problem with pressure, a leak somewhere or an under performing pump.

 

[Niloc]

4 bar is nowhere near enough, the rail should be way more, the system can be upto10,000 psi when running. You have a problem with pressure, a leak somewhere or an under performing pump.

Hiya

I know it's not right should be 2900 I think to work the injectors for starting. The hp fuel pump is a reconditioned new unit and there are no visible leaks.
I am wondering if the pump is not being asked to provide the right pressure to the rails because the computer doesn't want to start the car. Some kind of failsafe but I could be miles off.

 

[KJowner]

Possibly, you need to see the leak off from the injectors and the rail, why was the CP3 replaced?

 

[Niloc]

Possibly, you need to see the leak off from the injectors and the rail, why was the CP3 replaced?

Hi

Sorry being a bit thick here what is cp3?

Colin

 

[KJowner]

The Bosch CP3 is your high pressure fuel pump, the one that supplies the rail. Sorry I should have explained.

 

[Niloc]

Hi
I thought it may be but just wanted to make sure.
The pump was removed because the pressure was low at the rails.
I was going to get it checked but in the end the testing cost was nearly the price of a refurbed one from a local place so just replaced it .

 

[KJowner]

Ah, I see.
My guess at this point is injector leakoff or pressure control valve dumping fuel. I assume the quality valve was replaced along with the pump? (The bit the cable plugs into)

 

[Niloc]

Hiya
I did get a replacement valve but we didn't fif it yet.
I will pass on the suggestion for a pressure leak test as well hopefully something will work.
Thank you for the suggestions
Colin

 

[KJowner]

To be honest the leakoff tests should have been done before the garage started to change parts, randomly swapping parts gets expensive quickly!

 

[Niloc]

To be honest the leakoff tests should have been done before the garage started to change parts, randomly swapping parts gets expensive quickly!

Hi

He may have done them I will check with him

 

[Niloc]

Hi

He may have done them I will check with him

To be fair to the garage it was my decision to replace the pump based on the cost of having the pump tested by a company to supply a fully reconditioned unit .
The garage suggested that the pump may be faulty due to the low rail pressure .
He may have already performed leak tests which led him to suspect the pump.
He has been very helpful so far and I haven't asked to be informed of every step he does in his diagnostic.
But having said that I will ask to make sure.

Colin

 

[Niloc]

Hi
Still got a problem with my 2.8crd kk cranking but not starting.
Initially had crankshaft sensor code but replaced and no difference so tested the existing one and it was fine.
I had the fuel pump checked the wiring checked and the timing checked but no problems with any of those.
My next port of call is if the immobiliser is causing this but I have no idea as how to check or even disable the immobiliser temporarily if necessary.
Has anyone have an idea as to how to check this please.

Thank you
Colin

Hi all
is anyone aware of a company in the uk that is able to test a cherokee kk ecm unit.
i am still chasing the crank but no start problem and we have tested all that we can think of and running out of options.
One of the few options remaining is an issue with th3 ecm that is preventing starting so have taken it out in the hope that someone has the experise/ facilities to test and diagnose the unit.
I have tried ecuexpress and although helpful in saying they can clone to another unit they tell me these ecms cannot be tested or they haven’t got the hardware to test them.

a
Any advice or suggestions anyone.

Thanks
colin

 

[KJowner]

I've used 'The ECU doctor' in the past, not for a Jeep but the service was excellent.

 

[Niloc]

I've used 'The ECU doctor' in the past, not for a Jeep but the service was excellent.

Thanks I will give them a try