Hi, I’m new to this.
My xj 93 2.5l petrol sputter at rpm 3k. Like not getting enough fuel. I had this issue last time and the fuel pressure was low. So I bypass the ballast resistor and the pressure was in range.

But even the ballast resistor is bypassed, still having this issue. My voltage is lower abit.
what can be the issue?

 

Likely the fuel pump itself.

 

but I just changed new fuel pump. If alternator not giving enough power, will the fuel pump won’t function properly??

Before this also had bucking issue. So I bypass the ballast resistor. After the bypass, it was ok for few months and had same issue again.

parts change recently :
fuel pump
fuel filter
fuel assembly
fuel injector
exhaust manifold
TPS
fuel regulator
IAC

even after change everything still having bucking issue. Can rev higher than 3k rpm. And dies sometime when start from stop.

my alternator is not charging properly. The voltage somewhere at 10.45V. And during night after ON light dropping to 10V sometimes.

any idea?

 

You didn't state that in your original post. Have you ever changed the fuel filter?

Your signature needs correcting I think. Here's how.

Default ATTENTION ALL USER: Please read before posting!!!To all users of CF:

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The alternator not charging properly can cause all sorts of problems. I would fix that before replacing anything else. It could be the alternator, but also could be a bad wire or connection.

 

I had a honda with the same problem, it ended up being a clogged intake manifold. I had to go in and clean the carbon out. Hope this helps

 

Thanks for the suggestion. i will changed the alternator first. Then i update to u.

 

Thanks i will check on the intake manifold also.