Cranking gone from bad to worse

Hi everyone- For the past eight months to a year or so my '00 XJ has had the seemingly very common issue of not starting up on the first turn of the key, and will just keep trying to turn over to no avail . Nine times out of ten if its been sitting for more than a couple hours I have to turn the car on, wait a few seconds, and /then/ try turning the engine on, and then it works like a charm. Additionally, every so often when the engine starts up the car jostles in an odd way for a while, like not all the cylinders are firing, but that usually resolves itself quickly after I start driving.

Since doing an oil change the other day, I've tried to start the car a couple times and instead of getting the regular cranking noise that usually comes during the first attempt to turn the engine on, its silent for a second followed by a loud clunky grinding noise. The couple times this has occurred I turn it off, put the key in the on position for a few seconds, and then start the engine on the second go with no problems just like before.

Before it was a consistent inconvenience that I could get used to and live with- but this makes me think I've got a bigger more urgent problem. My worry is that I messed up the starter during the oil change without realizing it. A quick spot check and it looks okay, but I don't know where to go from here to isolate the problem, or if it even is the starter at all. If its helpful, I can take a video of all this. Any help is much appreciated!

Fuel pump probably losing prime, from leaky injectors.

Turn key to on until you hear fuel pump stop then crank.

BRIANHO13 said:

Fuel pump probably losing prime, from leaky injectors.

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Thanks! How would I go about testing the injectors to find out which ones are leaking? Is it as simple as running the car and then looking for fuel around each one?

No, you have to take out the fuel rail, and if it's never been out you may damage the injectors.

Unless the oil from the filter damaged got into the starter, changing the oil shouldn't of changed starting behavior.

Unclewolverine said:

No, you have to take out the fuel rail, and if it's never been out you may damage the injectors.

Unless the oil from the filter damaged got into the starter, changing the oil shouldn't of changed starting behavior.

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Thanks for the reply. So unless I plan on being ready to replace the injectors I shouldn't bother taking out the fuel rail? Is there anything else up the fuel line I could more easily check, at the very least to narrow down the problem to the injectors?



And yeah, I checked the battery and the starter and all are reading correct voltage so it's nothing there I don't think, just coincidental timing.

Or just turn the key and wait two seconds.

BRIANHO13 said:

Or just turn the key and wait two seconds.

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Like I said I've been doing that for a while now, I was just concerned that the worsening noise was evident of a more pressing problem.

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 ½ 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 gauge should read 49 psi plus or minus 5 psi.

2. Turn the engine off and immediately clamp the rubber fuel line ( if equipped ). Watch the pressure gauge and see how long it takes to loose pressure.

If the pressure remains above 30 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 one or more leaky injectors.

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.

Tim_MN said:

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.

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Thanks for the response, this is super helpful! I'll keep doing the key-on-key-off thing until I can afford to replace the fuel pump assembly.

My 2000 has a gas tank skid, Class III hitch, and rusty bolts, I have been priming for at least 10 years. Eventually I am going to cut a hole in the cargo floor and replace the fuel pump.