tylerspyler

Hello, when I first start my 2000 in the morning as long as I crank it long enough (1-1 1/2 cranks) it starts no problem but if I do not crank it enough it will sputter a second then makes a sound that sounds like it is backfiring into the intake. then it takes at least 5 or more cranks to start (even if I put my foot to the floor or prime the fuel pump). It does this and has done it since I got it. I do have a glasspack but it did it before I put it on, because thats what I thought caused it. runs perfect after it starts and has plenty of power (the other day i raced a 2005 dodge 1500 with the 5.7 and was neck and neck till he hit his limiter). any help is appreciated.

tjwalker

The check valve is located on top of the gas tank and is part of the fuel pump assembly on 95.5-2001 vintage 4.0 XJs. When the check valve starts to fail, it reduces fuel pressure to a point where an extended crank 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 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 the 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 this symptom. Sounds strange but it definitely does happen. Have battery load tested if you have any questions; 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, the check valve within the
fuel pump module, or a fuel tube/line is leaking. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Consult gauge manual for more information on this 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 - possibly the 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 wish as it doesn't mean the fuel pump itself is going bad. Normally, the check valve is replaced as an entire assembly as you have to drop the gas tank to access the assembly. Fuel pump assembly consists of fuel pump, regulator, check valve, filter. If you do replace the fuel pump assembly, purchase a high quality OEM style unit. Some cheap aftermarket assemblies don’t hold up and fail prematurely.

tylerspyler

Well from what you said, I don't think my check valve is bad because it starts up on the first try in 1-1 1/2 cranks but if it does not start that first time, the second time I try it will not start till after a few seconds of cranking. also my battery holds a steady 13.7 volts and 14.8 at idle.

The only thing that could be the problem is injector issues. I will do the pressure test this weekend and see what it is when the problem happens.

Thank you for the info.