Hi everybody.

My wifes '02 XJR did something funny last weekend. Wife was driving it home and it just stalled out on her. No codes no warning lights. Just stalled at a stop light. Restarted just fine but didn't want to stay running. She had to nurse it to get it the mile back to the house.

I went out and it started right up, idled fine and sounded fine. So... this week I have been driving it because she travels a good deal to get to work everyday and I didn't want a repeat of what happened to her on the highway.

It was fine form me all week until this morning. It stalled out twice on me on my 10 mile drive to work. Same thing, slowed or stopped and the engine just died. No codes no warning lights. Only a read out on the LCD that the engine had stalled. Both times I had some difficulty restarting.

I was really acting like the fuel was either contaminated or like it was running out of fuel.

So far I have done a fuel pressure test. With the engine running the fuel pressure was 38psi. According to All Data this is correct.

The funning thing is, that when you turn on the key without the engine running the fuel pressure is zero. On my other cars the fule pump kicked i once the key was turned on to bring pressure up then it cuts off.

The other funny this is the fuel pressure took about 10-15 seconds to reach the 38 psi.

So my questions are:

Should the fuel pressure be above zero with the key on engine off?

Should the pressure climb faster than it did?

I'm going to replace the fuel filter this afternoon. It has only been about a year since the last change, but it is a cheap first step. Then I'll recheck the fuel pressure.

I'm also going to check the fuel relays, to make sure they are ok.

My gut is telling me fuel pump(s) but wanted opinions. Not looking forward to pulling the tank for nothing.

 

Was the LCD readout "Restricted Performance"?

On the SC models, there are two fuel pumps. As described in another thread, the secondary fuel pump is the one that is supposed to pressurise the fuel rail on initial key on. It also kicks in above 3500 rpm. The primary fuel pump takes over once running.

On the other hand, fuel pressure should be maintained in the fuel rail even with key off. That would point to a failed fuel pressure regulator or valve at the fuel pumps. You can test by attaching your fuel pressure gauge, observe readings before starting, start engine, stop engine, and observe carefully to see if fuel pressure then drops. For on the road observations, use a long hose and tape the gauge on the OUTSIDE of the windshield.

You can test the fuel pumps with key off by jumpering the pins on the individual relay sockets to listen for pump operation. The pin arrangement is shown on the relay or use a wiring diagram.

 

check the battery

 

Thanks Plums.
No restricted performance call out. Been through that one already. Thankfully was able to get away with cleaning the throttle body and electrical connectors.

Fuel pressure maintains after shutting down engine. There was just no fuel pressure until after the engine started.

So I guess I need to check the secondary fuel pump/relay?

 

because of the way they are used by the ECM, check both primary and secondary pumps as well as relays.

The system is designed so that by pulling one relay, the remaining pump should take over both duties. But, testing this way throws a code which will either go away after putting the relay back, or by clearing codes with a scan tool.

So, your choice as to which way to test ... jumper with key off, or pulling relay and starting engine.

Even though the vehicle will run with one pump, it is not safe to depend on it. When one pump goes, the other is not far behind. Don't ask how I know.

 

LOL Plums.

On my way home from work today the car was fine. I stopped by the parts store (BIG BOX Type) to check on the availability of parts.

While I was there I had the battery tested. The battery was so bad I'm very suprised I didn't have I wasn't having trouble getting it started. So $185 bucks latter, I have a new battery. No problems going home from parts store.

I'm going to re-check fuel pressures in the morning. Too cold and damp out tonight.

 

glad you are amused

 

I'm just glad I'm not the only one that has crappy stuff happen to me. Not that I want it to happen to anybody else I'm just glad the trip isn't so lonely.

 

So today I re-ran the fuel pressure test. Same results only now with the new battery the pressure jumps right up to where is should be.

Not satisfied that I didn't have a bad fuel pump I jumpered the relays to force the pumps on. #1 fuel pump kicked right in. #2 dead.

So... it looks like I have a fun time ahead pulling the tank.