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Stalling and restarting issue

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Old Jul 29, 2021 | 05:50 AM
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Exclamation Stalling and restarting issue

lately when im driving around and i floor the accelerator, my engine stalls and has trouble starting up again. i suspect a faulty CPS, can anyone verify that this issue is a symptom of a faulty CPS? what else could it be?
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Old Jul 29, 2021 | 08:47 AM
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Verify? No. Is it a likely suspect? Yes. Does it restart once it cools off?

Assuming nothing mechanically wrong with the engine, you need spark and fuel. So you would have to test for both.

What year is your XJ?
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Old Jul 29, 2021 | 05:00 PM
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Originally Posted by Saudade
Verify? No. Is it a likely suspect? Yes. Does it restart once it cools off?

Assuming nothing mechanically wrong with the engine, you need spark and fuel. So you would have to test for both.

What year is your XJ?

i have a 1989 limited. Yes, eventually when it cools down it starts fine. how would u recommend i test for fuel?
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Old Jul 29, 2021 | 10:24 PM
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Originally Posted by sambjd
i have a 1989 limited. Yes, eventually when it cools down it starts fine. how would u recommend i test for fuel?

There is only one valid test for fuel. A fuel pressure gauge. You can usually rent one for free at Autozone or similar stores.


Yes, I agree with Saudade that the CPS is possible, but check your fuel pressure first. A marginal pump will give those symptoms.
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Old Jul 30, 2021 | 07:33 AM
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That's not really a symptom of a faulty CPS.

Before I spent a dime on parts, I would go to www.cruiser54.com and complete Tips 1,3,4, and 5. Take less than an hour.
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Old Jul 30, 2021 | 09:03 AM
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Fortunately, your 89 has a fuel test port on the rail. Take the cap off and connect the fuel pressure gauge. Turn the key to ON but do not start. The pressure should read around 39 psi. Now start (if it can). The pressure should drop to around 31 psi. Finally, remove the vacuum line from the end of the pressure regulator. The pressure should jump back to 39 psi. Once you reconnect it, it will drop back to 31 psi. This will verify your fuel pump and pressure regulator are good.

As for dies when hot, that's exactly what my '88 did once upon a time. Took 20 min or so with the hood up to cool off enough to start and then died once it got hot again. It was my CPS. There are a number of YT vids on testing and changing the CPS. Cruiser's tip #50 also details the test.
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Old Jul 30, 2021 | 09:53 AM
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Originally Posted by Saudade
Fortunately, your 89 has a fuel test port on the rail. Take the cap off and connect the fuel pressure gauge. Turn the key to ON but do not start. The pressure should read around 39 psi. Now start (if it can). The pressure should drop to around 31 psi. Finally, remove the vacuum line from the end of the pressure regulator. The pressure should jump back to 39 psi. Once you reconnect it, it will drop back to 31 psi. This will verify your fuel pump and pressure regulator are good.

As for dies when hot, that's exactly what my '88 did once upon a time. Took 20 min or so with the hood up to cool off enough to start and then died once it got hot again. It was my CPS. There are a number of YT vids on testing and changing the CPS. Cruiser's tip #50 also details the test.
You can rent the pressure gages for free from autozone or Oriely. Easy to figure out how to use, plus there are a million YouTube vids on it.. it helps to have a second person in the driver's seat, but can be done with just one. Just not able to actually watch the gages. The needle locks in place at max.
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