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Will not stay running?

Tiny
ECLECTIC ECLECTIC
  • MEMBER
  • 2005 OPEL ZAFIRA
  • 1.8L
  • 100,000 MILES
Greetings. I have the vehicle listed above z18xe. It starts and shuts off. Checked fuel relay/pump turns on. I have spark. Replaced cam and crankshaft/coil. It starts and idles if I cover the intake air filter or throttle body. Code from opcom says crankshaft low input signal. It does start and runs if I cover those. Thank you.
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Saturday, July 15th, 2023 AT 7:15 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Please understand, this vehicle isn't offered in the US, so I don't have manuals for it. However, I will try my best to help.

By placing your hand over the air intake, you limit the amount of air entering the combustion chamber. The first thing I think of is there is an engine vacuum leak at a different point on the engine allowing unmetered air to enter the combustion chamber.

Do me a favor. Take a look at this link. It explains how to locate a leak. See if you are able to find anything.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, let me know if you have a live data scan tool. Also, take a look at this link, it describes the most common symptoms of a failing crankshaft position. See if it mirrors anything you experience.

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Let me know what you find or if you have questions.

Take care,

Joe

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Sunday, July 16th, 2023 AT 8:30 PM
Tiny
ECLECTIC ECLECTIC
  • MEMBER
  • 21 POSTS
Greetings. Thank you, Joe. I have Op-com and it would give MAF or camshaft sensor. I replaced the cam and crank sensors. The fuel relay earth to the ECU is a common fault. I bridge the fuel relay. I have fuel in rail, and it starts and shuts off. It starts and idles if I cover throttle body or air intake. Thank you.
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Wednesday, July 19th, 2023 AT 10:33 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
If you restrict the air going into the engine and it runs, something is telling me there is a large vacuum leak. By restricting the air intake, the engine is getting an air/fuel mixture it can run on. Have you been able to check for leaks?

Joe
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Wednesday, July 19th, 2023 AT 8:30 PM
Tiny
ECLECTIC ECLECTIC
  • MEMBER
  • 21 POSTS
Greetings. Thank you. Wouldn't it still run without the air intake connection/MAF? I have seen a video of one running. I'll connect the air intake hoses to throttle body.
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Thursday, July 20th, 2023 AT 11:46 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Yes, in most cases when the MAF is disconnected, the PCM will resort to a predetermined setting to the engine can continue to run.

Joe
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Thursday, July 20th, 2023 AT 6:27 PM
Tiny
ECLECTIC ECLECTIC
  • MEMBER
  • 21 POSTS
Greetings. I have connected the air intake hoses. It still shuts off unless I cover it. It has fuel in rail, but the fuel pressure gauge shows nothing. I bridged the relay still shuts off.
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Saturday, July 22nd, 2023 AT 2:01 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

It sounds like the fuel pump has failed. If the pressure is that low, it won't run. Actually, by covering the air intake is the same as having a choke on an older vehicle carburetor. That forces less air and more fuel to enter the combustion chamber.

So, if I understand, the fuel pressure doesn't show any pressure. If that is the case, the pump is likely the problem.

Here is a link that explains in general how one is replaced:

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Let me know if that takes care of the issue.

Joe
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Saturday, July 22nd, 2023 AT 9:36 PM

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