I have a 99 XJ and since I bought it a few weeks ago I've noticed that it takes longer and longer to crank up in the morning. And today, after sitting for only a few hours, it took a really long time to crank up. I've been meaning to replace the fuel filter but I've been so busy fixing other stuff and changing all fluids. Gotta change diff fluids tomorrow and install a new rear diff cover (fluid was leaking from plastic 8.25 fill plug, decided to put on RuffStuff 3/8" cover with metal plug and drain).

My question is, do you think the longer and longer starts are due to a clogged fuel filter, a fuel pump about to give out, or something else. I'm thinking of changing the fuel filter and if that doesn't fix it then get a fuel pressure gauge and start doing some diagnostics.

 

Is it throwing a code? (Is the check engine light on?) If so go to some place like Advance Auto Parts and have them read the code. They plug in a code reading device under the dash for free. That will rule out stuff like O2 sensors. If it is not throwing a code, then fuel pressure is a good place to start. It should be right at 28-30 lbs at the fuel rail schrader valve when the key is turned to the "ON" position (without turning over the starter) AND it should stay pressurized after the key is turned off. If it does not get to approx. 30 lbs and stay there, then you probably have a filter or fuel pump issue. If the fuel pressure is OK, then do the easy stuff. Change out distributor cap and rotor, plug wires, plugs. If you know those are OK, then it's probably the CPS (crank position sensor) or MAP sensor. My money is on the CPS or fuel pump.

 

...so it probably does not have a distributor. So ignore that part in my reply above.

 

Do a search, this was recently covered.

 

The check engine light isn't on, and hasn't come on at all since I bought it. I figure it's probably a fuel pressure issue. I've searched and read about recent fuel issues that have been posted, but my truck isn't dying during idles or really dying at all. Once it starts it's good. I've driven it on a couple 500 mile round trips in the last couple weeks without problems. And it's only taking about 6 or 7 seconds to start now, but it's been getting longer and longer. Was about 1 or 2 seconds a few weeks ago. I figure I'll change the fuel filter and check the fuel pressure and go from there. I was just wondering if it starts taking longer and longer to crank up if that could be a sign of a clogged fuel filter or if I'm probably looking at something more expensive.

 

Do a leak down test.

 

OK, got the instructions in my manual, I just need to pick up a fuel pressure gauge. Also, apparently on the 99 the fuel filter is located on top of the fuel pump assembly and not on the frame rail, "A separate frame mounted fuel filter is not used with any engine." - Chrysler 99 Service Manual, p. 14-4. So I guess I need to drop the tank to replace the fuel filter. That's a bummer.

Oh, also, I did a little experiment today. I turned the key to the "On" position and listened for the fuel pump to stop pumping, took about 4 or 5 seconds. Then turned starter and it started right up. So, I'll do the leak down test because it's probably losing pressure somewhere.