Clunk noise when attempting to start it?

1998 CHEVROLET BLAZER
200,200 MILES • 4.3L • 6 CYL • 2WD • AUTOMATIC
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BRIBRI4275
  • MEMBER
  • 24 POSTS
My blazer has the vortec engine. I had to replace the fuel pump and then had problems with it starting. It would just make a clunk sound every time i would try to start it. I'm pretty sure the fuel pump wouldn't make that noise, so i tried to look elsewhere. I change the crankshaft sensor and followed the direction on how to adjust it and when i took it out the second time, all this gas came out with it. Is this supposed to happen? I know a little about cars but i've never seen this happen. Please help.
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Sep 7, 2021 at 12:51 PM
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JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
Hi,

If that is gas, we have a concern. No, that shouldn't happen. Do me a favor. Check the engine oil level. See if it is overfull and if it has a fuel smell to it. I have a feeling the knock you were hearing was a cylinder nearly full of gas. Liquids don't compress.

When you replaced the fuel pump, did you confirm fuel pressure was within spec? Was the fuel pressure regulator inspected?

If that is gas, then it is likely getting into the engine due to excessive fuel pressure, a bad injector, or a bad cylinder.

If you haven't, here is a link that explains how to test fuel pressure. Do this as well and let me know the results.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know what you find with the engine oil.

Take care,

Joe
Sep 7, 2021 at 7:45 PM
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