outofexile1988

I was wondering everybody....is my engine taking about 6 or 7 cranks to cold start normal? The engine once turned on runs great...and if I turn it off, run into the store and come back out a minute later the engine starts right up. Is this normal!? Thanks for clearing this up for me.

99KeeSport

When is the last time it had a tune up?
Good spark? (and good plugs?)
Are the spark plug wires/cap/rotor old?
Is the battery strong?

It could mean quite a few things.
Remember: you need good fuel, good spark, and air.

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.

outofexile1988

Alright well @ 99KeeSport I had recently bought this car about a month ago...as soon as I got it I changed the spark plugs and gapped them to .035, new spark plug wires, new distributor cap, new distributor motor, new air filter, royal purple oil change, BG radiator system flush so it should'nt be anything within the engine. @ tjwalker im definelty going to try "the poor mans prime" and see how that works and Ill update by the end of today. thanks for the info. p.s. when i did the tune up, everything was OEM!!!!!!! including the spark plugs...so God knows they probably never did anything with the fuel pump or filter.

redrunner

If it is an 88 you have a Renix system in it. It must reach 300 rpm before it will spark. It takes longer for them to crank. I have two of them and both have to turn over longer than you would think. Never fear its just the nature of the beast!

tjwalker

His is a 1999.

outofexile1988

Ohhhh yeah I tried that "poor mans prime" and it started up real quick...can this problem bear to wait for repair? like i said the engine runs smooth after starting but i wont have the money or time to fix it over the next few months (2-3 months). Thx for the info!

outofexile1988

oh btw tjwalker...since you are really knowledgable in Jeeps with my Jeep, is it neccessary to relief the fuel pressure before working on the fuel system? I heard that some jeeps have a modern fuel system where the system isnt pressurized until the fuel pump turns on. is this true?