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  #1  
Old September 23rd, 2020, 15:04
essvee essvee is offline
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Starting issue - plenty of ignition power and fuel but requires two cranks

97XJ, its been doing this for as long as I can remember.

Jeep has been sitting for a day - you go out, turn the key, it will crank and sputter if you hold the key down but it will never start.

Same behavior if you turn the key to prime the fuel pump and then turn to ignition.

If you back off and try to start again, it'll start right up.

No codes, no codes stored, no codes pending.

Fuel pump assembly was replaced, no impact.

Fuel pressure is good, though it does bleed down over a day. Even so, priming the system before trying to start it should alleviate any issues (that's what I think anyway).

Battery seems fine, but regardless it behaves exactly the same if you jump it from a running truck.

Any ideas?
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  #2  
Old September 23rd, 2020, 15:59
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Tim_MN Tim_MN is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Possible ignition switch problem, but don't cross off wiring issues.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Battery terminals and battery wire connectors should bright silver, not dull gray/black and corroded. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt onto.

Jeeps do not tolerate low voltage, bad wire connections, or poor grounds.
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  #3  
Old September 23rd, 2020, 16:45
essvee essvee is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Quote:
Originally Posted by Tim_MN View Post
Possible ignition switch problem, but don't cross off wiring issues.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Battery terminals and battery wire connectors should bright silver, not dull gray/black and corroded. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt onto.

Jeeps do not tolerate low voltage, bad wire connections, or poor grounds.
All ignition wires have been replaced with new cables, clean grounds across the board.

The other thing that makes this suspicious is that after that initial crank, it starts every time. No hesitation, no weak crank.

It's not like the plugs fire off of a starting capacitor...
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Old September 23rd, 2020, 16:54
essvee essvee is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

(By ignition wires I should say the battery harness, high gauge replacements, wing-nut style terminals, all the usual)
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  #5  
Old October 5th, 2020, 08:02
AdvTurin AdvTurin is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

I am new here (first post) and saw your issue. I also have a 97 sport 2wd. I had a similar issue, started second crank. ran a little rough then purred. I read it could be injectors that leak in to the cylinder (lowering pressure in the fuel line) or fuel pump that has a check valve built in. When it fails the fuel runs back to the tank leaving air in the line. So first crank pressurizes the line and second crank it comes to life. I replaced my fuel pump in the tank and problem solved!!
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  #6  
Old October 5th, 2020, 08:08
AdvTurin AdvTurin is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

See first poster rookie move.....I see you replaced the pump. Look in to the injectors. Your issue sounds so close to what I had. And I was changing all sorts of stuff including the injectors and nothing...then I changed the fuel pump and all good. what pump did you put in? I would still question that
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  #7  
Old October 5th, 2020, 11:49
essvee essvee is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

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Originally Posted by AdvTurin View Post
See first poster rookie move.....I see you replaced the pump. Look in to the injectors. Your issue sounds so close to what I had. And I was changing all sorts of stuff including the injectors and nothing...then I changed the fuel pump and all good. what pump did you put in? I would still question that
Hey thanks for chiming in!

The pump is good, tested pressure and behavior from the rail and everything checks out. The idea of an injector leaking into a cylinder over time and making a stumbly first start is very interesting though. That brings injectors to the top of my list of things to test!
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Old November 19th, 2020, 11:27
essvee essvee is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Bumping this thread now that I've had some time to look into the injectors and everything seems fine.

Summary at this point:
If the jeep has been sitting for a day and I go to start it - I turn the key to power, hear the fuel pump prime, then turn for ignition, and the first turn always stumbles and rarely starts. Second turn starts every time, and starts strong. Runs and drives just fine. If its been ~6 hours or so since I last drove it, it'll start right up.

I've:
upgraded the power harness to the battery, so I've got clean grounds there
replaced the fuel pump
checked fuel pressure - pressure is good, and considering I've been letting it prime before cranking, that takes out the check valve and fuel pressure issues before the rail
Took out the injectors and let it sit overnight, testing AdvTurin's idea that an injector was leaking into the cylinder. Put the injectors back in the following day - same behavior.

The issue is so consistent that it really does seem like the physical action of cranking the engine a few times is what makes it ready to start.

Gonna try swapping my cam position sensor next - definitely shouldn't exhibit this behavior but its cheap enough to try and return if it doesn't change anything.
Also going through any oil covered ground straps - cleaning and replacing.
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  #9  
Old November 19th, 2020, 11:42
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cherokeecrawler cherokeecrawler is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

What CPS are you getting?

If you're not getting a Mopar CPS then you're already making a mistake. Aftermarket ones are known to be bad out of the box, go bad early, etc.
Only one I would get if i couldn't get a Mopar is an NTK only because they make some of the other sensors from the factory, even then I' be skeptical.

Seen too many people replace the CPS just for it to be bad and it still be the problem all along.
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  #10  
Old November 19th, 2020, 15:36
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Quote:
Originally Posted by essvee View Post
If the jeep has been sitting for a day and I go to start it - I turn the key to power, hear the fuel pump prime, then turn for ignition, and the first turn always stumbles and rarely starts. Second turn starts every time, and starts strong. Runs and drives just fine. If its been ~6 hours or so since I last drove it, it'll start right up.


When a 1997 to 2001 Cherokee won’t start on the first try day after day, the first thing to suspect is a failed check valve on the fuel pump. The fuel pump check valve is supposed to hold pressure in the fuel line while the engine is off. The check valve is located on the fuel pump and located inside the gas tank. A failed check valve allows the fuel to drain back to the tank. This results in one or more of the following symptoms:

SYMPTOMS

• Longer than normal cranking times
• Never starts on first try, almost always starts on the second try
• Rough idle for a few moments of idling
• Rough running for first block of driving
• Little or no fuel pressure at the fuel rail test valve similar to this -

1- Key in on position; fuel pump primes for 2 seconds then stops. 0 PSI
2- Cranking over the engine. 2-3 PSI
3- Engine starts and idles for 20 seconds. < 5 PSI
4- Engine idles and fuel pressure creeps up to 45-50 PSI.


POSSIBLE CAUSES

• Failed check valve on the fuel pump in the gas tank.
• Leaky fuel injector(s) may be the true cause of your problem, but more likely they are simply contributing to the check valve issue.

Testing of the fuel injectors should show if any are faulty and are allowing fuel to drain into the cylinder. Either problem can allow heat soak to vaporize the remaining fuel in the fuel rail, and you may be dealing with a bit of vapor lock as well, especially in warmer weather.

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


There are a few solutions to the problem –

1. Turn the key to ON for 5 seconds and let the fuel pump prime. Turn the key to OFF, turn the key back to ON for 5 seconds, start the engine.

2. Crank the engine for 3-5 seconds, pause, and crank the engine again. It will almost always start on the second try.

3. Replace the fuel pump assembly in the gas tank. The check valve is not a separate part and cannot be serviced. This is both expensive and time consuming because you have to remove any hitches and skid plates and then remove the gas tank from the vehicle.

You can use solutions 1 or 2 for as long as you want to, they do not harm anything and the fuel pump will continue to function for many more years.


If you do replace the fuel pump assembly, purchase a high quality OEM style pump assembly such as Bosch or Carter. Some cheap aftermarket fuel pump assemblies, like Airtex, and Precision don’t hold up and will fail completely within 12-18 months.
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Quote:
Originally Posted by bimmerjeeper


Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
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  #11  
Old November 19th, 2020, 15:38
essvee essvee is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Unfortunately, as detailed above, I've been through all of that.
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  #12  
Old November 19th, 2020, 20:39
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Runnin'OnEmpty Runnin'OnEmpty is offline
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Re: Starting issue - plenty of ignition power and fuel but requires two cranks

Quote:
.........Gonna try swapping my cam position sensor next .......
That's what I'd do. The cam sensor generates a signal every two
engine revolutions and it might not be putting out a signal on the
first crank. Since the engine starts on the second try, there
wouldn't be a trouble code.

Also check for excess play in the distributor shaft, where the 'flag'
might contact the cam sensor.
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