Slight power loss between 3500 and 4000 - 4500 rpm

[asylum]

I have a slight loss of power between 3500 and 4000 - 4500 rpm. This results to a kind of power jump, like a (very) mini vtec kicking in at 4000 - 4500 rpm. Well, I feel it because I am a psychopath and I know my car. But anyone else would not even feel it and be upset by this.

As this is the rpm at which the fuel pump resistor switches from low to high speed, I linked the problem to the fuel pressure. I bypassed it and do not feel this anymore.

I plan to change the fuel filter as it is original ('91, 40 kmiles) and hope this is enough to recover. What do you think ?

I hope the fuel pump is ok.

 

[solidol]

Start small by making sure there is no resistance to the flow (replace filter first). Check FPR too. If issue still exists I think you would have to dig deeper which means fuel pump (but that's unlikely). Don't run the pump at higher pressure for long.

 

[jwmelvin]

Don't run the pump at higher pressure for long.

What is the issue you would have with this? Seems like most cars run the fuel pump full speed all the time. As long as the FPR can handle the excess flow I don’t see an issue.

I agree replace the filter. May be time for a new pump though. Not really a big deal if so.

 

[solidol]

What is the issue you would have with this? Seems like most cars run the fuel pump full speed all the time. As long as the FPR can handle the excess flow I don’t see an issue.

Stressing fuel pump for no reason. Think about why Honda implemented switchover in the first place. Should be no problem to operate in high pressure mode just don't consider it permanent solution. CT flipped it up as business as usual for low boost kits btw

 

[jwmelvin]

Think about why Honda implemented switchover in the first place. ... CT flipped it up as business as usual for low boost kits btw

I understood the reduced-voltage mode to be primarily for noise reasons, because of the close proximity of the pump. Some devices don’t like operating at reduced voltages but I think the pump is fine either way.

CT sure did flip it up with the voltage booster. I’m glad to have removed that thing from my car.

 

[Old Guy]

I have a slight loss of power between 3500 and 4000 - 4500 rpm. This results to a kind of power jump, like a (very) mini vtec kicking in at 4000 - 4500 rpm. Well, I feel it because I am a psychopath and I know my car. But anyone else would not even feel it and be upset by this.

As this is the rpm at which the fuel pump resistor switches from low to high speed, I linked the problem to the fuel pressure. I bypassed it and do not feel this anymore.

I plan to change the fuel filter as it is original ('91, 40 kmiles) and hope this is enough to recover. What do you think ?

I hope the fuel pump is ok.

A fuel pressure test might give some indication as to whether there is a pump problem. Replace the filter, remove the by-pass on the resistor and check the fuel pressure as set out in the service manual procedure. If the pressure tests out OK, then your pump might be fine. The problem is that the service manual test is not under high demand conditions. If your drive the car test is satisfactory then you are probably good to go. If you don't get the required pressure as set out in the service manual test then your pump is due for replacement or your fuel pressure regulator has gone out of spec.

 

[asylum]

Well I swapped the fuel pump resistor between this NSX and my track one and problem is gone ! I am happy that, for the time, the fuel pump is still ok.