Hello All-

My wife drove home yesterday with engine service light on, but no identifiable symptoms. She came in for a while, and when she returned to the truck to leave, the truck would not start or crank. All lights on dash and interior flashed and a clicking sound came from dash. I assumed a failed alternator or battery, soI replaced the battery and bought an OBDII scantool. Upon replacing the battery, it would crank and act as if it would start, but almost immediately shut off as if the fuel was cut off. I checked and reset the inertia switch on the firewall, but no luck. When I turn the key back to off and then back to start, it acts as if it will start again, but again fuel shuts down. I have removed the crank sensor, and there is no visible damage to it. Could the low voltage or high amp draw from the battery have damged it internally? Is there a way to check it with a multimeter? Am I way off on considering the crank sensor as the culprit?

Thanks in advance for any help-

mtfife

 

We need to know the yr of your trk.
Pull one spark plug out and see if you have spark, if you have spark then your crank sensor is good.
Next open the cargo door and have your wife turn the key to the "ON" position, you should hear the fuel pump kick on, it will only run for a few seconds and then shut off.
If that is good then check fuel PSI, there is a schrader valve on the fuel rail, wearing safety glass' and standing off to the side and making sure that there is nothing hot or open flame, crank the engine over for a few seconds and then press in on the valve, if fuel squirts to the ceiling then you have fuel PSI, if it dribbles then you dont.
And no, low voltage will not hurt anything.

 

It is a 2000. The odd thing is that it fires up all cylinders, but then shuts down after half a second or so, so I know spark is getting there. It just seems that the ECM is either shutting down the coil or the injectors, based on some type of immediate feedback from the sensors. If I turn the key back to off, then back to start, it fires on all again, but then shuts down after half a second or so.

Thanks-
mtfife

 

Check your fuel PSI right after it shuts off. Your fuel pump might be weak and it can only hold PSI for a short time.
Try this first though, start the trk,after it shuts off do not turn the key off leave it in the "ON" postion and then try starting the trk again, does it start WITHOUT cycling the key to the "OFF" position?

 

OK - rpleaced the Crank sensor; still aks same as before. I pulled a spark plug and it sparks for several revs, then apparently the computer is shutting of the spark. Other than the crank position sensor (since it is new), what else could cause the computer to shut down the coil? Any ideas out there?[:@]

Thanks -
mtfife

 

Did you do like I said and re-start the trk WITHOUT turning the key off?
I think that you are stuck on the computer but it is somthing else.
This is for a DI, but since you are stuck on the computer I will give you the link, I still dont think that is what it is though.
http://forums.lr4x4.com/index.php?showtopic=86

 

Yes - I have already tried that, and it will not fire after the initial several revolutions. In fact, I have removed a spark plug and it fires for the first few revs, then will not spark after that. It really seems to operate completely normally for the first few revs, then it seems as though the computer is shutting down the coil. I have replaced the crank sensor but not the cam sensor. If the cam sensor is bad, would the computer still shut off the coil or only the injectors? BTW, I tried spraying carb cleaner into the throttle body with now change in operation.[/align][/align]Thanks-[/align][/align]mtfife
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Have you checked your fuel pump yet? You will not beable to spray enough carb cleaner into the engine to keep it running on carb cleaner alone.
Not sure about the cam sensor.

 

Yes there is strong flow at the rail schrader valve.

 

I am at a loss. You could try replacing the cam sensor and see what happens.