98 XJ Starting Problem

I'm having trouble starting my 98 XJ with 84K miles. When the enigne had been at rest for an extended period of time, it will refuse to start when I key to the start position the first time, but it will crank normally. If I key off and then key back to the start position, the enigne will crank and start right up. I've had trouble starting the truck for a while, but it has gotten worse in the last 2 weeks. In the last 4 weeks, I've installed an MSD6 box, MSD coil, and plugs. I added these parts as improvments not to repalce damaged or faulty components. The cap, rotor, and wires are all less than a year old. I've done fuel pressure test and at the first start of the day, when I key to the on position I'm getting about 5psi. When the engine is running, I'm getting about 48psi. When I key off, the pressure drops almost immediately to 20psi then continues to drop to 0 in about 5 minutes. I just ran a diagnostic using my scan tool and I got a P351 DTC, but the Check Engine Light is off. This forum has been extremely helpful in the past and I'm hoping to get some help figuring out what I need to do to get this fixed.

sounds like the problem is with the loss of fuel pressure. I would start checking everything on the system starting with the filler cap. If nothing is found it could be the pump on its way out. You might want to pick one up and be prepared for the day when it quits.

That's kind of what I was thinking, but I want to make sure this is really the issue before I drop $250 on a fuel pump module and drop the tank.

Thanks for the input.

I have had the same problem seince the day i bought my 98. I did some research and the only thing that i could find is that there is a problem in the fuel pump with a check ball or something to that effect. I just ordered a fuel pump so i will let you know if thats a fix.

I've had my 99 xj for almost a year and have always had this problem...never even tried to fix sincei its really only my 'beater' vehicle...but would like to since its kind of annoying...please keep us updated on any resolutions

I'll be looking forward to your reply with the results of your pump replacement XJ9888. Are you replacing just eh pump or the fuel pump assembly, which included the pump, sending unit and strainers?

Im replacing the entire module. Its having some trouble with vapor lock as well so hopefully that will fix it to. Its being shipped right now so i will let you know!

After verifying the fuel pressure test results, I decided to go ahead and swap out the fuel pump. I also installed a Tach Adapter from MSD to take care of the P0351 DTC I was getting. I changed out the entire fuel pump module in about 2.5 hours with the help of my brouther in law. It was pretty straigth forward and the pump module I bought at NAPA was a perfect match for the factory pump. The XJ is running great and starts up right away. I believe that the hard start problem is fixed, at least unitl I need another fuel pump.

X2 on the fuel pump. Starts right up now.