Fuel Pump Resistor 0.73 vs 0.55 ohm

[dquarasr2]

I just received a shipment from Japan supplier. I thought I was buying 196171-0080 which has 0.73 ohm resistance but they sent me 196171-0082 which has 0.55 ohm resistance.

Anyone know for sure whether this part will work in place of the 0.73 ohm resistor? 1991 NSX.

 

[jwmelvin]

Since you can bypass the resistor without significant issues, I’d say you are fine with the slightly lower resistance.

 

[furinax]

I don't see anything in the manual about the fuel pump resistor specs but the Fuel Injector resistor has a range of 5-7 Ohms on Page 11-94 of the manual. These resistors always have a range due to manufacturing so I am sure it is fine.

 

[asylum]

I do not know for the value. But this resistor can "fail" or cause problems : http://www.nsxprime.com/forum/showthread.php/206494-Fuel-pump-resistor-hot-like-hell-!!!

 

[dquarasr2]

Thanks for the responses. I figured that if FI guys bypass the resistor that it probably wouldn't hurt but I thought I'd ask.

Reason I purchased a replacement is because the car exhibits that "flat spot" in acceleration between around 3600 and 4300 RPM. As soon as I hear the VTEC solenoid on the left side of the dash click, the car accelerates as normal again. I understand this to be the classic problem of bad fuel pump resistor, weakening fuel pump, or fuel filter overdue for replacement. So I started with the resistor. I'll install over the coming weekend and post an update.

Again, thanks for the responses.

 

[jwmelvin]

VTEC should be considerably higher rpm but the fuel-pump resistor is switched out right around 4k rpm. So that does seem like something worth trying. It may also be a sign of weak fuel pump, where it is struggling with the reduced voltage from the resistor. That was what led me to bypass the resistor as a temporary thing to help before I replaced the pump.

 

[Old Guy]

I would fast forward to doing the fuel pressure test as set out in the service manual. The original resistor might have gone out of spec causing your problem; but, I would assign a low probability to that happening. Resistors tend to remain in spec or fail completely. The one thing that might happen is that heat from the resistor causes a poor electrical connection leading to deteriorating pump operation; but, that does not seem to be a factor with the NSX.

The new lower resistance resistor (or completely by-passing it as jwmelvin describes) might mask the symptoms associated with an ageing pump. The fuel pressure test is not 100 % definitive (you can still get false positive results); but, if you are below the pressure results described in the test, the writing is on the wall. Low pressure can result in driveability issues and error codes and if and when the pump finally dies, it can leave you in a bad place (at the side of the Alaska Highway in my case).

That would not be the VTEC solenoid that you are hearing. It might be the fuel pump relay (that by-passes the fuel pump resistor) which is mounted on the inside of the back bulk head sort of behind your right shoulder.

 

[dquarasr2]

Update: Installed the 0.55ohm resistor and based on short drive it has cured the 3600-4300 RPM sluggish acceleration. Removing the bracket from the 27+ year-old original resistor was a small adventure. Broke three (count 'em, THREE) impact screwdriver phillips head bits. Fourth time the charm. Hoping the 25% lower resistance does not lead to premature fuel pump failure but time will tell. Luckily this car is driven only a few thousand miles per year these days (yeah, I should correct that.)

Old Guy, the clicking I was hearing is on the left-side dashboard, which is where I understand the VTEC solenoid is.

Yes, I am anticipating an aging fuel pump failing soon. I will bite the bullet and arrange to have it replaced soon, along with the fuel filter.

 

[Old Guy]

Old Guy, the clicking I was hearing is on the left-side dashboard, which is where I understand the VTEC solenoid is.

The VTEC solenoids are attached to the spool valves that are mounted on the left side of the engine's heads. If you hear something clicking in the dash, it is something other than the VTEC solenoid / spool valves.