1998 XJ Won't start on 1st try, fires right up on 2nd attempt / slow start - JeepForum.com
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Unread 07-26-2010, 11:31 AM   #1
spenceuiuc
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1998 XJ Won't start on 1st try, fires right up on 2nd attempt / slow start

So my XJ has been slow to start lately; it has not wanted to start up on the 1st time I turn the key. But if I let the key turn back to on and then give it a 2nd go, it fires right up.

It will eventually start on the first turn of the key, but it takes ~5-8 second and seems like the engine is struggling to get going. But the 2nd time, it seems to fire up just fine.

Where should I start troubleshooting?

Thanks!

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Unread 07-26-2010, 02:50 PM   #2
tjwalker
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Spence, this is such a common question on your vintage XJ that I created this document and then cut and paste it whenever the question comes up, which is about twice a week or more!
Good luck and let us know what you find!
-------------------------------------------------

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. (stay away from Airtex) Some cheap aftermarket assemblies don’t hold up and fail prematurely.
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Unread 07-26-2010, 04:08 PM   #3
spenceuiuc
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Quote:
Originally Posted by tjwalker View Post
Spence, this is such a common question on your vintage XJ that I created this document and then cut and paste it whenever the question comes up, which is about twice a week or more!
Good luck and let us know what you find!
This info gives me exactly what I need to get started--- thanks tjwalker!

Also, is the Jeep fuel check valve integrated into the fuel pump assembly, or can it be replaced separately?
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Unread 07-26-2010, 06:22 PM   #4
jeepmanjc
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me and my buddy have to crank both ours twice and they fire right up the second time, not really a problem just a annoyence, just be happy like we are that they start. ive been doin it for since i got mine
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Unread 07-26-2010, 08:19 PM   #5
spenceuiuc
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I am definitely having the symptoms of the faulty check valve. I may try an inline check valve. I found a few on eBay in various size--- does anyone know what the I.D. is on our fuel lines?
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Unread 07-26-2010, 09:32 PM   #6
Smittyman
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This started to happen to my XJ not too long ago. It started immediately after filling up at the gas station. Same gas station as always and the same amount as always. The first two starts after filling up it was doing what is described above. Since then I just don't turn the key and go. I now turn the key to on for a few seconds, then crank it. Hasn't happened again since. I'm not sure if I got a bad batch of gas (sounds slightly humorous) or if the prime trick is working. I'll try just the straight start and go soon.
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Unread 07-10-2012, 10:01 PM   #7
flipsidem
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leaky injector

Great post on the diagnosis of the OPs problem. I think I might have the leaky injector on my '98 ZJ. Any ideas on how to find out which injector is leaky? A whole new set would be pretty expensive. Thanks.
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Unread 07-11-2012, 09:59 AM   #8
ELMER
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Fuel problem

Great diagnostic advice. I have this crank no fire problem on a 2001 Cherokee classic 4.0 L. I was preparing to order a fuel pump module. The OEM module is available from MOPARPARTSONLINE for $304.00. However after reading this, my defect may be an injector. OEM Injector would be $46 or $54. This advice will help me to identify the correct part to replace. I need to do the fuel pressure test. If the pressure test indicates an injector, how do I identify the faulty injector. But then, if identified as a single faulty injector now, and with 185,00 miles, should a single injector be replaced, or all six?
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Unread 07-11-2012, 03:37 PM   #9
ELMER
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Wait-a-minit

I checked the website WERMOPAR.com to find an OEM pump only for $122.

Injectors for like $52 apiece.

I dunno, but am thinking I can renew all these parts for a lot less than the dealer would charge to replace the pump only.

At 185K, the injectors become questionable.

This system does not have an external fuel filter, it is all in the tank.

How contaminated must mine be after 12 years?

There are pics of these in another thread in JEEPFORUM. + Nasty.

Just thinkin'
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Unread 07-11-2012, 03:51 PM   #10
ELMER
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Fuel correction

Dooooh. I rechecked the fuel pump info, It is not pump only, but module at $291.00. Sorry to elevate your BP. Even so, WERMOPAR seems to be a good source.
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Unread 07-11-2012, 04:43 PM   #11
ELMER
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Rebuild

If you can tolerate the wait, WITCHHUNTERERFORMANCE.COM will rebuild the injectors for $21. The dealer pricing now has tagged on a $5.00core charge to foil rebuilders.
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Unread 07-11-2012, 05:43 PM   #12
buildin1XJ
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Spence X1 on TJ Walkers post he gave you all the info you need to diagnose the problem. O'Rielys rents out a very nice fuel test kit.
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Unread 07-28-2012, 03:49 PM   #13
ELMER
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replacement injectors

OEM new injectors would be about $57.00 each this includes a $5.00 core charge. I notice that ROCKAUTO has GB reman injectors for $25.00 (plus a refundable core charge). Does anyone have experience using the GB reman product???
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Unread 07-28-2012, 10:36 PM   #14
ELMER
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Fuel injectors

http://fuelinjectorconnection.com/sh...?productid=281

They have a really interesting video.

http://fuelinjectorconnection.com/sh...?productid=281
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Unread 08-05-2012, 04:58 PM   #15
ElColo
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Hmmm. Just ried TJWalker's test. Rough start up. So, I guess I'll head out to O'Reilly's. Just did a preliminary search on fuel injectors. Looks like a lot of talk about going to a junk yard and putting in used injectors from a dodge Neon. I don't think I like that I idea. If I'm going to have to replace the injectors, I'd rather put something new in and of good quality, preferably designed for the engine. Any thoughts? Can any one point me in the right direction? Does Bosch make fuel injectors?
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