My X300 is intermittently dying just as it catches, usually 2 or 3 times before catching and running.
Starter cranks, engine starts (briefly), RPM needle goes to 1000 and back to 0 over about 1 second.

A little pressure on the throttle seems to help, making me think it's fuel delivery not lack of spark. It only does this periodically.

Any ideas?

 

When was the last time you changed the fuel filter? It does sound like it's a fuel issue from your description.

 

Hi Rhett,

The first things that come to my mind are the fuel pressure regulator and check valve or non-return valve, which work together to maintain pressure in the fuel rail. Over time one or both components fail, so the fuel pump must re-pressurize the rail every time you start the car after it has been sitting a while. Your symptoms could indicate that your engine is starved of fuel until the pump builds the pressure back up.

Short of doing a pressure leak-down test on your fuel rail, one thing you can do is to pull the vacuum hose off of the FPR to check for the presence of gasoline, which indicates failure of the diaphragm. Since your car is 19 years old, and FPRs don't last forever, it might be a good idea to replace it now. The X300 part is the same as the one on our late XJ40, EBC2606. I found an OE Bosch part number 0 280 160 234 on Amazon for U.S. $78.00 including postage (eBay sellers offer other brands such as Beck/Arnley, sometimes for less than $40.00).

The fuel pressure regulator (FPR) is mounted on the forward, or return end of the fuel rail. See the link below for photos that show how I replaced the FPR on our '93.

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The fuel check valve or non-return valve works with the FPR to maintain pressure by preventing fuel from escaping back into the fuel tank. I don't see a separate in-line check valve on the X300 parts diagrams so I assume that on the X300 it is built into the evaporative flange on the top of the fuel tank as on our '93 (our '93 also has a check valve in the bottom of the fuel pump canister inside the tank which helps keep the fuel pump primed). If your check valve has failed (and that's a strong possibility), the easiest solution is to add a new check valve in the fuel line somewhere between the tank and the rail. The photos at the second link below show how I did this on our '93. Installing the check valve in the feed hose in the engine compartment, ahead of the fuel rail, is easier than installing it under the fuel tank as I did. I had the entire rear suspension out to rebuild the differential when I installed our check valve there, so I had easy access. But see my photos showing the first location where I tried the check valve - that should work fine for you if your fuel lines look the same as ours.

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I'll look forward to reading the input of others.

Cheers,

Don

 

It could be as simple as you need to adjust your cam position sensor a little bit, or it's a sign your crank sensor is in it's way out.

 

There was an aftermarket ground disconnector attached to the battery for long term storage. The car has started flawlessly since we took it out.