MOOSE16285 said:
pick up coil and crankshaft position sensor are synomous?! so whats inside the distributor they said i need to look at, like under the rotar n all... suppose to be electrical i need to look at there... quick poll, where do i get a 90 jeep xj FSM from?! haynes doesnt give details to all i need!
Hah! Haynes is the manual I use to prop up that odd leg on the workbench out in the garage...
Fuel, Air, Spark. Gotta have all three...
Air - as long as the intake is open, air isn't a problem.
Fuel - two things to start with here -
Fuel pump. You can usually hear this running. If you really want to hear it, jump the ballast resistor in the driver's fenderwell with a heavy-gage jump lead and turn the key on.
Fuel injection pulses - if the CPS is shot, you won't get these. The quickest way to check them is with a "Noid" light - it plugs into the FI connector. These can be had for about $5 at a well-stocked local.
Fuel pressure and delivery are usually only a problem if the pump has failed anyhow. There is a test gage that attaches to the Schrader valve on the fuel rail - idle spec is 30-31psi, ~39 psi with the vacuum line to the regulator disconnected.
Spark - Not much to check here
CPS - if the CPS is shot, you won't get any spark at all. The CPS generates timing signals for both fuel injection and ignition control.
Ignition Coil/Module. I haven't seen too many of these fail. Check the power lead and the trigger lead (the power lead should be a steady +12VDC nominal, with something like +12VAC at the trigger with the engine being cranked. A scope is best, but you probably don't have one. If you have an analogue meter, it will respond faster on +12VDC and you'll see the needle wag.)
The sensor in the distributor, under the rotor, is the Camshaft Position Sensor, or "SYNC" sensor. The RENIX system will work without the SYNC sensor - but not as well. The purpose of the SYNC sensor is to let the ECM know when the #1 cylinder is coming up to fire, and therefore allow it to tell which rotation of the crankshaft it's dealing with (the crank goes around twice for each cam rotation.)
If the SYNC sensor has failed, it will be a "long start," but the system will "guess" which cylinder is coming up until it gets working. Therefore, if you had a failed SYNC sensor, you'd still be able to start up.
As far as finding a 1990 FSM, good luck. Most sources only print them going back 10 years - anything beyond that is EBAY or get lucky here. I've got one, and while I'm willing to pass along information, I ain't about to part with it. You might want to check the reference section of your local libarary - they often have Mitchell or Motor manuals, and those are the ones you typically find in general shops.
5-90
