My Jeep has been having problems starting ever since it has started getting cold. It starts every time but it cranks for about 3-4 seconds. I cant really figure out what the problem could be. I changed the wires, plugs, cap, and rotor a couple months back along with new alternator, and battery. TPS is new as well along with a cleaned TB. Any suggestions?

 

do you just get in the truck, turn the key and try and start it?

OR

do you turn the key, listen for the fuel pump to prime, then try and start it?

Mine does the same thing....especially after its been sitting for a few hours/overnight.

I found that if I just jump in and try and start it, it takes several cranks for it to run. If I turn the key on, and listen for the fuel pump to run/prime the fuel lines, then try and start it, it does so almost immediately.

 

Maybe the check valve in the fuel pump. See if turning the ign on and off a few times first helps. That can prime/pressurize the line.

 

ok thanks guys ill try that. my brothers Silverado had close to the same problem and priming the fuel pump did get it to start on the first time. I completely forgot about that. but theres got to be a problem if I have to do that every time right?

 

Maybe the check valve in the fuel pump.

 

This may sound odd but I would guess your battery is getting old and weak. 4.0l can do some strange things when the battery gets weak.

 

I'm having the same issue ever since the weather got into the 40's this last week. I always wait a second before cranking the engine after turning the key to 'run', but I'll have to try priming the fuel pump a few times and see if that helps.

 

My first jeep did the same thing....I could crank and crank and crank and it wouldn't start. I bump it once then try again and it would fire right up.

My current Jeep started to do it and I got tired of it so I replaced all the goodies in the tank. That fixed it, Now almost 100k later it is starting to do it again. I crank and it won't start, bump it once and then try again and it fires every time.

 

yep, fuel psi is bleading off over time. only fix is fuel pump/module

 

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. I specifically seek out Bosch fuel pumps as they are the best in the business. Stay away from Airtex, as IMHO, they have a bigtime reliability problem.

 

Great advice. Where is the check valve located on my '91? Is it in the tank as well?

 

The check valve on a 90.

 

while doing the "poor mans prime" or whatever it was called, it did end up starting after the first crank. I dont think that it would be the battery due to it being less than 6 months old. but you never know.

 

Mine does the same thing and i thought it might have had something to do withthe nuetral safety switch so i tried putting the car in nuetral and tried starting it and it starts right up now. Not saying its the issue but try it out

 

if it was the NSS it wouldnt crank what so ever. I know cuz mine is going bad as well. and thats not the problem