Jeroen

I have a small problem with my '98 Jeep, 4.0L.

Since a couple of weeks, when cold, it will only start on the second try.

It cranks well but won't fire up even if I keep cranking it for 10 seconds. Second try it'll fire up immediately. Even if I crank it for 2-3 seconds, stop and the try again it'll fire up immediately, but not the first time.

Battery is fine, replaced plugs, leads, distributor cap and rotor a while ago.
Once it's running it idles well and it runs fine, with reasonable MPG.

Any thoughts?

Jeroen

KodiP.

Well how cold does it get at your house? You might have to get a block heater.

bajaman1

I have the same problem with myne,but its done it since i got it,so it dont bother me,then again it's a jeep,and in all my family we have 8 jeeps,and the old ones start a the second try,and the 2005 and the 2001,do the same,dont see anything bad on that...but,if yours just started doing that it is weird!1

Jeroen

Not cold at all yet, I'm in Kansas City. So it's still above freezing, or just under during night.

Jeroen

wildbill1

Have you tried turning the key to the "on" position for a few seconds before turning to "start"? Maybe try it and see if you can hear the fuel pump.

You might not have enough fuel pressure on the first try.

johnybsic

Mine did the same thing.
How about If the jeep has been running before you shut it off? will it start 1st try?
If so do this:
let it sit overnight, in the morning find the schreder valve on the fuel rail. Press it in with a small screwdriver or such (Carefull of your eyes) you should get a pretty healthy puke of fuel out of it.
If you only get a small hiss like air escaping, then your lossing fuel pressure (draining back into the tank)

Mine did this for a while.

I place a check valve in the fuel line, and it cured it right away. My buddies did the same thing. Theres a check ball in the pump assy, that goes bad.
put and aftermarket one in if you find thats the case (Do a search for XJ check valves, theres a BMW P/n you can buy online. costs about 15$ and comes with the ck valve/ lines/ clamps.)

Just an idea!

Jeroen

Keeping the ignition in the on position for a few seconds doesn't make a difference. If I shut down the engine and restart it, it'll fire up immediately.

I'll do that check, but I'm not sure I understand how that could cause this behaviour. On the second try everything is fine.

Jeroen

johnybsic

Leaving the key on will not "prime" the system enough to overcome the air (or lack of pressure) in the fuel line. You may hear it go "WHURRRRRRRRRR" but thats not enough

Make sure the jeep hasent been ran for a length of time (Overnight is best) before you test.

Pull off the platic cap circled in the picture. theres a small valve like the one on a tire, Press this in.
Like i said you should get quite a bit of fuel that comes out, If you only get some air escaping or a tiny bit then thats your problem.

look at it this way. When you shut the car off the check (One way) valve in the fuel tank holds the pressure in the line, Ready for the next time you start the car. It SHOULD hold the same pressure for nearly a month without much drain back.
If the valve is stuck, It will allow the fuel in the line to simply go back into the tank in a short amount of time (10min- overnight).
Then when you turn the key the first time, there is not enough fuel in the rail or lines to start. cranking it momentarily then letting go will "Prime" the system again. *2nd crank it will start just fine.
Also if you have been driving, and lets say you just run into a store real quick and back, then the fuel will still be holding enough pressure to start with no problem.

So basicly
1. make sure it has been sitting overnight
2. remove the plastic cap
3. press the small pin in the center of the valve
4. *fuel bursts out (enough to get your hand wet) -Good
* hear only air escape (Hiss sound) or just a small amount (dribble)- Bad

Mine & my friends had exactly the same condition you explained, Both were fixed once we diagnosed it as (check valve fu*ked up)

the stock check valve is in the pump, cannot be replaced without buying a whole new pump $$$/ hard work.
An aftermarket check valve placed in the fuel line after the tank (cut and splice, very easy) is about 30-45min & 15$ or so.

If you search around google, or the cherokee fourm (XJ fuel check valve) (Check valve) etc you can find some write ups with pics on how to do it.
IF Thats whats wrong
Its pretty common and specific to Jeep cherokee XJ's
Good luck!

4wheeldrivenewbie

Hey does my 89 happen to have the same valve on the fuel rail cause id like to check that also. I seem to have to crank and crank for about 25 seconds usaully when i here burr burr burr then varoom. I have fairly new deep cycle battery installed so i know my battery isnt bad. i hope its this.

Jeroen

Finally got around checking this little valve today. And sure enough there was very little fuel that came out after I let the Jeep standing idle during the night.

Jeep's been starting fine last week, so for now I think I'm just going to leave it. If it gets worse I know what to do.

Thanks for the advice.

Jeroen

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.

tjwalker

double post, damn HP computer!

WantACherokee

Great thread. My '87 4.0L XJ seems to have the same issue, as in it won't start on the first crank even if you crank it for a while, but starts on the second crank. Do the older XJ's like mine have the check valve issue as well? Looks like I need to determine if it's that, or an injector or FPR issue.

tjwalker

You have a Renix XJ (87-90) By design, the engine is not going to fire until the computer (ECU) gets a signal from the crankshaft position sensor and measures that signal to indicate that 300 rpms while cranking has been met/exceeded.

Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.

You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.

Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.

Other than good basic tune-ups on a regular basis which should always be reviewed, (plugs, wires, cap, rotor, fuel filter) the above suggestions are things that will help optimize start times on a Renix engine.

alloutperform

my 98 did it and my fuel pump crapped out so i changed it.. the symptom got better but still would do it every once in a while i changed my injectors to the ford yellow ones and it seems to have cured it