Engine vibration after replacing the fuel pump with a High-Pressure fuel pump?

AMANAMAN1

MEMBER
2015 CHEVROLET EQUINOX
2.4L
4 CYL
2WD
AUTOMATIC
239,000 MILES

The vehicle listed above, Ecotec 2.4L. Background: I successfully replaced the timing and balance shaft chains, all the sprockets, tensioners, guides, and cam phasers. The engine was then quieter and smoother than it's ever been. Yay me! I also had a problem with the engine running on and fuel in the oil. So, a week later I replaced the high-pressure fuel pump. Immediately on startup I noticed a slight vibration and rumbling noise at idle that was not there until I replaced the fuel pump. No codes, no stalls or lack of acceleration, just slightly rougher idle and slight vibration since the new HP fuel pump. I know the pump is cam driven and the noise almost sounds like it's coming from the phaser end of the intake cam but can a new (stiffer?) Pump cause this? It was idling perfectly smooth beforehand.

Thursday, May 4th, 2023 AT 5:47 AM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
54,138 POSTS

It sounds like you may have a defective high-pressure pump, but when the pump has off did you check the camshaft lobes for wear? This is a big problem with this engine. Also, there is an alignment tool that needs to be used when doing the job, here are the instructions on how to replace the high-pressure pump so you can see what I am talking about. If you don't use the alignment tool you can damage the pump when you are tightening it down to the engine. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

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Thursday, May 4th, 2023 AT 10:33 AM

AMANAMAN1

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Thanks for the info, Ken, I appreciate that. No, I was not aware of the alignment tool, but I was very careful when reinstalling the two mounting bolts, alternating hand tightening until it seated then alternated each bolt until tight, then torqued. I did look at the cam lobes when I had the valve cover off doing the timing chain and didn't see anything glaringly obvious, no grooves or valleys or pitting, just normal looking even wear patterns. Not so sure I looked at the fuel pump lobe. As it turns out though, when the wife got home this evening (100 miles or so later) it sounded much quieter than it was yesterday after I replaced the pump, and it wasn't shaking or vibrating like it was. It was actually running pretty smooth. Not sure what that was all about but it seems to have evened out. Maybe it just needed to shave a little metal off the cam lobe, LOL. Dunno.

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Thursday, May 4th, 2023 AT 4:15 PM

KEN L

MASTER CERTIFIED MECHANIC
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LOL I like a car that fixes itself! If the problem returns I would replace the high pressure pump again. Use 2CarPros anytime, we are here to help. Please tell a friend.

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Friday, May 5th, 2023 AT 10:24 AM

AMANAMAN1