Hesitation when increasing RPMS

[JoelZ]

Hi All:

Hoping for a little advice here. My 1978 280Z runs fine but when driving it if I allow the RPMs to get too high the car starts to hesitate and almost feels like it is bucking. Even when parked if the RPMs are allowed to get about 2,500-3,000 it hesitates and the RPMs drop despite my foot still being on the gas and there is a clear hesitation. Here is what I have done so far: Fuel injector cleaner in the gas tank, new wires, rotor, distributor cap, and checked spark plugs. Anyone experience this before or have any suggestions? Thanks!

[Pomorza]

What fuel injector cleaner did you use? How much of it did you run and what gasoline did you use while using it?

Jan

[JoelZ]

Lucas additive to gas tank. Gas tank was about 2/3 filled with regular unleaded gas. This is the same gas I have used since I bought it (not that I have driven it very much) and when I bought it I drove it about 100 miles back to my home and did not have this problem. In fact it did not start occurring until the day before I posted the question. From talking to people the suggestion that seems to make the most sense is either a fuel filter and/or a fuel pump. I have no idea how old these parts are or if they are even the original parts.

Thanks!

Joel

[leftover z]

There ya go. Put in a new fuel filter. Was a simple fix for me.

[JoelZ]

New fuel filter did the trick, just glad it was not the fuel pump!

The fuel that was left in the older filter was very dirty. I am sure the pump I exchanged was very old. It was not the original but still it was very old.

On the the next project...

[leftover z]

Don't be surprised if the fuel filter clogs up again in a few months. The gas tank was probably cruddy, and the fuel injector cleaner you put in the tank probably knocked some of the gunk loose. I'd probably change the filter in a few months, then change it once per year.

[JoelZ]

Will do, thanks for the advise. I need to take it for a good ride in the next couple weeks so I can burn some of the gas through and get the filter doing its job and then change it in a few months