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Hello all I'm having some trouble diagnosing a no start problem on my 96 xj6. I suspect a faulty crankshaft position sensor but I would like to hear what you guys think. The car will start on starting fluid (which I know is a bad method) so at first I started looking at the fuel delivery system. I'm getting pressure at the rail tho I have not put a pressure gauge on it yet. I backed the fitting off and when I crank the car I get a strong steady stream of gas. Fuel pump and relay both seem to be good sooooo. I'm thinking it is probably the ckps. Any imput would be greatly appreciated
Also, follow the pigtail wiring from the CKPS, to the connector just above it. Seperate that connector, CLEAN it out. They fill with crud over time, and the contacts stop contacting.
Might fix it, might not. Fixed mine a long while back.
Last edited by Grant Francis; 08-24-2016 at 03:48 AM.
There are lots of possibilities. It may help us if you give us some context: did the no-start condition come on suddenly, or were you gradually having more and more difficulty getting it to start?
Just a couple of thoughts off the top of my head: the fuel injectors receive a constant 12V supply on the Black/Light Green wires and are operated by the Engine Control Module (ECM), which connects each injector to ground in sequence. The injector 12V supply comes from the ECM Controlled Relay, which is in the front right corner of the engine bay. It might be worth checking for corrosion on the relay terminals and in the relay socket (disconnect the battery negative cable before using a small wire brush and zero-residue electrical contact cleaner spray in the relay socket). You can also try swapping one of the non-essential relays in that area for the ECM Controlled Relay. This diagram from page 27 of the Electrical Guide identifies the relays in that area:
One thing to be aware of is that there are certain conditions under which the ECM will shut off the fuel injectors. One of those is when the accelerator pedal is depressed all the way to the floor for Wide Open Throttle (WOT). The same can also happen if the ECM senses a WOT signal from the Throttle Position Sensor (TPS) even if the throttle isn't actually wide open, due to an electrical problem.
A couple of documents that may be helpful are the 1996 Electrical Guide and the AJ16 Engine Management System training manual, which you can download at the links below courtesy of our forum member Gus:
There are lots of possibilities. It may help us if you give us some context: did the no-start condition come on suddenly, or were you gradually having more and more difficulty getting it to start?
Just a couple of thoughts off the top of my head: the fuel injectors receive a constant 12V supply on the Black/Light Green wires and are operated by the Engine Control Module (ECM), which connects each injector to ground in sequence. The injector 12V supply comes from the ECM Controlled Relay, which is in the front right corner of the engine bay. It might be worth checking for corrosion on the relay terminals and in the relay socket (disconnect the battery negative cable before using a small wire brush and zero-residue electrical contact cleaner spray in the relay socket). You can also try swapping one of the non-essential relays in that area for the ECM Controlled Relay. This diagram from page 27 of the Electrical Guide identifies the relays in that area:
One thing to be aware of is that there are certain conditions under which the ECM will shut off the fuel injectors. One of those is when the accelerator pedal is depressed all the way to the floor for Wide Open Throttle (WOT). The same can also happen if the ECM senses a WOT signal from the Throttle Position Sensor (TPS) even if the throttle isn't actually wide open, due to an electrical problem.
A couple of documents that may be helpful are the 1996 Electrical Guide and the AJ16 Engine Management System training manual, which you can download at the links below courtesy of our forum member Gus:
Well gentlemen thanks for your help. Turned out to be water in the fuel. Got the tank drained and cleaned. Bleed the fuel lines and change the filter. Now shes up.and running. Running rough but running. I will be changing the plugs coils oil and probably another fuel filter just to be on the safe side within the next few days
Thanks for the follow-up. Make sure the filler-neck drain is not clogged. They tend to plug up with leaves, dead bugs and other such flora and fauna if parked outside, particularly if a shaded area.
I make it a practice to pour a bit of water in the compartment (WITH FUEL CAP INSTALLED TIGHTLY!!!) periodically to check drain operation ever since I took the lad's 96 VDP for a top-up and flipped open the door to find it filled to the brim with rainwater. Make sure you stop pouring before it gets up to cap-level if it isn't draining and then sop it out with towels or whatever until you can get the drain free-flowing again.
Thanks for the follow-up. Make sure the filler-neck drain is not clogged. They tend to plug up with leaves, dead bugs and other such flora and fauna if parked outside, particularly if a shaded area.
I make it a practice to pour a bit of water in the compartment (WITH FUEL CAP INSTALLED TIGHTLY!!!) periodically to check drain operation ever since I took the lad's 96 VDP for a top-up and flipped open the door to find it filled to the brim with rainwater. Make sure you stop pouring before it gets up to cap-level if it isn't draining and then sop it out with towels or whatever until you can get the drain free-flowing again.
That was the problem. I have since thoroughly cleaned the compartment and drain line. Thanks again everyone
08-23-2016, 07:41 AM
Crankshaft position sensor?
