Delayed Cold Starting

Hi all. Have a question about my XJ, and cant seem to find a solution.

The problem is not critical... When starting cold, it turns for a while before it fires. When it finally fires, she generally starts right up. Its just a lot of "dry" turns (for about 3 seconds) and then starts right up, no sputtering or rough idle. The motor runs great, no check engine light. When warm, fires right up, no problem. Hope this explains it well...

I have heard it could be the coolant temperature sensor, located very top front center of engine. (in line 6 engine). But, like I said, no check engine light, so not really too sure where to check.

Pulled some of the plugs out, they look fine. Wires good as well. Battery is strong. Not sure what else to check. Any ideas??

Thanks in advance!

fuel evaporation most likely

Hmm.. emissions thing then? usually that stuff loves to ignite the check engine light though... I was thinking maybe fuel system somehow. Any way I could check that?

It's normal. Gas evaporates. The emissions part is that the evap system captures the fumes and sends them back to the tank instead of letting them escape into the atmosphere. You can put a small bottle of Lucas fuel system cleaner ("Tune-Up In a Bottle") in your tank if you want, might help

What year?

Could be perfectly normal for a Renix XJ.

I see the thread got moved... makes more sence to be with OEM tech, sorry about that.

its a 97. I just rolled it off the used car lot like this, and fuel cleaning was another thing I was planning to add. Thanks for the advice!

On a 97 it is probably a bad check valve, of course on yours it is in the tank and you would have to drop the tank to get to the fuel pump assembly.

Live with it.

The check valve is located inside 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.

1. Connect the gauge at the fuel rail and start the engine. The gauge should read 49 psi plus or minus 5 psi.

2. Turn the engine off and immediately clamp the fuel line just ahead of the fuel tank. 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 - probably the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky 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. Fuel pump assembly consists of fuel pump, regulator, check valve, filter. If you do replace your fuel pump assembly, purchase a high quality OEM style pump. Stay away from the "el-cheapo" units. There are lots of threads of premature failure with those.

I've seen this information on another thread birchlakeXJ. This is my normal proceedure for starting my 99 XJ now (steps 1-3 & 5). Fires right up.

Thanks for the info birchlakeXJ! I will be out and about here soon this afternoon, and I will give that a try. Ill post back with the results!

BTW... my XJ is at 119000ish... due for fuel filter/pump change anyway? i guess technically these things should never be dirty, but I just bought it, and you never know what your getting into with used cars. I have been slowly making my way around all the filters, fluids... etc. in the jeep. Could it be done in a weekend?

Fuel pump assemblies on 97 and newer are not generally replaced as a preventive thing; they normally are replaced when symptomatic and testing leads to one or more of the components on the assembly failing.

As mentioned, you have to drop the gas tank to replace the assembly. If you've never done one of these before, would be a good idea to get a manual to help walk you through it. Not a small job but not a real big deal either.

Well, got to run the jeep around today. "priming" it worked like a charm!! so, thanks again birchlakeXJ for the info!! So, this means it is that check valve on the fuel pump assembly? I just thought it was a bit embarrassing to take people for rides, and have to crank it over for a while before it fires. This "poor mans prime" i can live with. Thanks again!

If you end up dropping the tank and replacing parts up there, you can save yourself a lot of headache for approximately $8 by getting two new J-bolts (part number j3240023, $1.92 each from funjeepsparts.com) and some new 3/8-UNC stainless steel nylock nuts and stainless steel washers from home depot, then simply cutting those bolts when dropping the tank. Believe me, it sure beats the hell out of spending an hour with a ratchet wrench and a pair of vise grips. Get the tank as empty as you can before dropping it, your arms and back will thank you.

4WDlifeform said:

Well, got to run the jeep around today. "priming" it worked like a charm!! so, thanks again birchlakeXJ for the info!! So, this means it is that check valve on the fuel pump assembly? I just thought it was a bit embarrassing to take people for rides, and have to crank it over for a while before it fires. This "poor mans prime" i can live with. Thanks again!

Click to expand...

If you are okay with "priming" it, then you should be good to go. Glad the information was helpful to you. arty:

It is most likely that your problem is the check valve. It's not impossible that some other component along the fuel route is bleeding off pressure, and there are techniques for isolating that (in the info) but more often than not the root cause is the check valve.

As mentioned, just because the check valve is failing does NOT mean that the fuel pump itself is failing. Many guys use the "prime to start" method and continue to enjoy service from their fuel pump assembly for a long time. Other guys just don't like the extended crank quirk and replace the assembly.

But if/when you start having actual fuel delivery problems, (fuel pressure testing with a gauge will tell you that) then the tank has to come down and a new fuel pump assembly installed.