96xjcherokeev

I have a 96 XJ4.0l. Had a bad fuel pump. Replaced fuel pump and battery. Ran great for 2 days 100 miles. went to move next day and would crank would not start. Fuel pump is not priming but if I jump the Fuel pump relay it does turn on but even then it just cranks and won't start. Replace CPS, check all grounds, all fuses are good. Swapped ASD relay with good relay still nothing. Any suggestions I have been searching forums and nothing has helped so far. All my dash lights work my gauges move when key is turned on.

jordan96xj

I noticed you didn't mention the fuel pressure in your post. You need to connect a gauge to the fuel rail and see what the fuel pressure is doing when you try to start, and when you jump the relay. Have you at least pressed the valve on the fuel rail to see if gas sprays out under pressure?

96xjcherokeev

Sorry I should've stated fuel pressure when relay is jumped is about 45psi. Also if valve is pushed while pump on fuel sprays out.

Radi

So...the fuel pump does not run for a few seconds when you turn the key to "ON"?
If you pull a plug, lay it on the valve cover with the wire attached, do you have spark?
Ignition switch connector look overheated or discolored?

tjwalker

45 psi should be enough fuel pressure to fire up your 96. With the newer fuel pressure system of the later year 96 XJ, the spec is 49 psi, plus or minus 5 psi.

So next step is to identify if you have spark and if you do have spark, is it a good quality spark. This is often missed.

As Radi already mentioned, take a plug out, keep it attached to the plug wire. Place the plug so the electrode is right near a good engine ground. Have a buddy crank the engine over while you watch. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white spark indicates a weak spark which may not be enough to fire the engine up. A weak spark is most often caused by a weak coil. You can also test your ignition coil for both primary and secondary resistances with a manual and a meter.

Good luck and let us know what you find!

96xjcherokeev

Awesome thanks guys plan on doing further testing this weekend on all things stated. One thibg I did see yesterday is that at my ASD and fuel pump relays the voltage is switching pins when turning ignition switch on or off but still doesn't sernd power to fuel pump. Will test spark and update. Thanks again

96xjcherokeev

Update tested spark. Getting no spark. Checked voltage for fuel pump pin on PCM and am gettung 12.5VDC with key positioned on. I'm thinking it may be an issur with the ASD circuit as that controls power to coil and fuel pump atleast from what I have read. No idea where to start checking that circuit though.