So I have been noticing over the past few weeks at a cold start first thing in the morning my XJ takes quite a while to start. It turns right over but it takes between 3-5 seconds to start. When the truck is warm she starts right up. I have a brand new alternator and battery so the only thing that might not be cranking normal is the starter. Anyone have any ideas?

 

Your cranktime is my cranktime.
One thing to check it the following:
If cold, turn your key to the on position, but NOT start. If all is well, you hear your fuelpump 'prime'. Turn back off and to on position (again not start) and do that about 4 times. Than start it up: if this improves the startup significantly, its likely ur pump.
(I believe its TJWalker who calles this the 'poor man's prime'). Initially mine did not improve and now it does with this, so another thing added to the list...

 

^x2 I just wait a few seconds till the pump is done priming then start it.

 

I can't really compare mine to yours because I have a renix and they take a while to start normally, but do the prime and see what happens. It helps a little on mine sometimes.

 

The check valves (there are two of them; one on the fuel pressure regulator and another on the fuel pump) are part of the fuel pump assembly on 95.5-2001 vintage 4.0 XJs. When a check valve starts to fail, it reduces fuel pressure to a point where an extended cranking time is needed to start the engine. It is a very common failure. I experienced it on my 99 at around 75K.

A good (and simple) way to help you troubleshoot this problem is called “the poor mans prime”

1. Turn key to ON position (do not crank the engine!)
2. The fuel pump will energize and run for a couple of seconds
3. Turn key to OFF position
4. Repeat above a two more times
5. NOW crank the engine over

If the engine starts quickly and cleanly after performing this procedure, you may have a check valve issue. If it starts and runs poorly for a few seconds, it could also be a leaky fuel injector resulting in the bleed down and the stumble upon startup is the engine clearing the excess fuel that has leaked into the cylinder because of the faulty injector.

Also be aware that a bad battery can give you starting symptoms as well. Have your battery load tested (any parts store will do this for free) if you have any doubt; your XJ does NOT like low available battery voltage. Be sure battery connections and posts are CLEAN.

Some troubleshooting tips for extended crank times:

Hook up fuel pressure gauge on the schrader valve on the fuel rail

Start engine and bring to normal operating temperature.

Observe test gauge. Normal operating pressure should be 49.2 psi (plus or minus 5 psi)

Shut engine off.

Pressure should not fall below 30 psi for five minutes.

If pressure falls below 30 psi, it must be determined if a fuel injector, a check valve within the
fuel pump assembly, or a fuel tube/line is leaking. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Note: a quick loss of pressure is more often the fuel pressure regulator check valve and a slow loss of pressure is often caused by the fuel pump check valve. But either or both check valves can be to blame. Consult the manual that comes with the fuel pressure gauge and the Factory Service Manual for your year XJ for more information on this exact procedure, but here is basically how it works:

*Turn the engine off and immediately clamp the fuel line at the adaptor hose. Watch the pressure gauge and see how long it takes to lose pressure.

*If the pressure remains at 49 psi for an extended period of time then the problem is in the tank – most likely a check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky fuel injector.

You can limp a check valve problem along indefinitely if you like, as it doesn't mean the fuel pump itself is going bad. Perform the “poor mans prime” before cranking to speed up your starts. However, if you have a check valve issue and want to resolve it, it is recommended that you replace the entire fuel pump assembly for two reasons. First, you have to drop the gas tank to access the assembly. Secondly, with two check valves, replacing just the fuel pressure regulator where one of the check valve resides may or may not resolve your problem; remember there are two check valves; the other one is on the fuel pump.

The fuel pump assembly consists of fuel pump, fuel pressure regulator, fuel gauge sending unit, fuel gauge float, pickup filter and pigtail wiring harness. If you do replace the fuel pump assembly, purchase a high quality unit. Some cheap aftermarket assemblies have been known to fail prematurely. I specifically seek out Bosch fuel pumps as they are the best in the business. Carter is my second choice. Airtex is my least favorite choice and I won't install one.

 

Like I quoted. The man himself explained.