I have noticed that my 98 cherokee sport starts right up most the time, but randomly I have to hold the key way longer to get it to fire up or do a normal key bump and repeat and it fires right up.
does anyone else have an issue like this?
does anyone else have an issue like this?
Member
Mine usually starts right up, but once in a while I have a hesitant start, it's random, like I didn't turn the key enuff
Senior Member
Credit to tjwalker
Quote:
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.
Originally Posted by 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.
Member
Mine started flawlessly the first 2 days I had it...
Now it takes about 5 seconds... I guess I'm gonna run this test tomorrow and assess the situation at hand.
Now it takes about 5 seconds... I guess I'm gonna run this test tomorrow and assess the situation at hand.
Senior Member
I found the seat belt has a lot to do with it. 
Now before you jump all over me for saying that READ THIS POST!
If I jump and and try to start it right away it takes a few cranking turns.
However.....
If I get in and .....
1) Turn the key to the ON position
2) Hook up my seat belt
Then turn the key to the START position it starts right up.
Yeah I know the seatbelt really has nothing to do with it, and it is most likely the checkvalve but I felt silly turning the key off and on three times and figured if I turn it on and wait a few seconds the fuel line should pressurize. The problem was what to do while waiting those three seconds, so I hook up my seat belt.
Now before you jump all over me for saying that READ THIS POST!
If I jump and and try to start it right away it takes a few cranking turns.
However.....
If I get in and .....
1) Turn the key to the ON position
2) Hook up my seat belt
Then turn the key to the START position it starts right up.
Yeah I know the seatbelt really has nothing to do with it, and it is most likely the checkvalve but I felt silly turning the key off and on three times and figured if I turn it on and wait a few seconds the fuel line should pressurize. The problem was what to do while waiting those three seconds, so I hook up my seat belt.
Seasoned Member
I do the check valve thing everytime I get in my jeep and it starts up fine now, before it would take at least two cranks
Member
Just think of it as theft protection. They can break in, but they won't be able to get it started . . .
Member
Quote:
Exactly, then again i have a poor mans theft system with a removable steering wheel. Originally Posted by GreenJay
Just think of it as theft protection. They can break in, but they won't be able to get it started . . .
CF Veteran
my 88 renix always long starts
my 92 ho always fires right up
my 98 does whatever the hell it wants.. i have done tuneup, recent fuel pump (crapped out), and it got a crank sensor.. it just does its thing
my 92 ho always fires right up
my 98 does whatever the hell it wants.. i have done tuneup, recent fuel pump (crapped out), and it got a crank sensor.. it just does its thing
Member
Most of the time it just cranks and starts right away. Every once in a while it'll crank once, hang, then go, but that's rarely. Had a few slower starts last winter, but nothing too bad.
CF Veteran
mine takes about 4 or 5 seconds to start,i need a new battery to help it crank better
tjwalker
CF Veteran
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Yesterday
- Join DateNov 2010
- LocationIn the middle of Minnesota!
- Posts:5,840
- Year1999
- ModelCherokee
- Engine4.0
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Likes:156
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Liked:117 Times in 104 Posts
Try the "poor mans prime" that is noted in dukie's post of my standard response for these threads.
It takes all of 15 seconds and can generally tell you if your check valve is bad, which is a VERY common problem on 96-01 4.0 engines.
It takes all of 15 seconds and can generally tell you if your check valve is bad, which is a VERY common problem on 96-01 4.0 engines.