Does anyone have a spare fuel pump resistor?

[Tom_]

I'm having a total 'mare with my NSX; it's been at Plans Motorsport for a month now*. They're now waiting on a replacement fuel pump resistor, which they suspect is the cause of overfuelling/rough running which it's been experiencing since they did a clutch change and cambelt service.

They've got one on order, but have been told it will be the middle of next week before Honda can get one to the UK. I'm obviously keen to accelerate this :)


* the story of this may be told at another time; the main take-home message is that I'm nominating Kaz for an MBE... ;)

[Thunder]

Yes, I in have one in good state, but, I am in Belgium, I do not know time for transport, it will be can be too long for you

[AR]

I'm having a total 'mare with my NSX; it's been at Plans Motorsport for a month now*.. ;)


You are not the first one to have problems with them, like the member that a diff locked!

[forumadmin]

After a cambelt service? They sure they haven't got the cam wheels out of alignment by a tooth? There was another NSX on here that had that problem.

[Kaz-kzukNA1]

Hi, Tom.

7100
As I always carry my spare main relay and fuel pump resistor in my boot, you can try it but ....

If the fuel pump resistor is the problem, then you can bypass it by shorting the two female pins on the chassis loom side carefully.
This will force the fuel pump into high speed mode.

Under normal street driving condition, the fuel pump is in slow speed mode but at the time of engine fire up as well as above 4,000rpm with certain intake manifold pressure, the pump will operate in high speed mode.

Regardless of the fuel pump speed, the fuel pressure is always controlled at 3.5kg/cm2 ABOVE the intake manifold pressure by the pressure regulator.

So, if they bypass the fuel pump resistor by shorting the two female pins and still having the problem, then, I don't think it is the fuel pump resistor issue.

I don't want to interfere with other people's service so just want to provide some idea for you.

First of all, as in my SMS, if they made any changes to the ECU condition such as disconnecting the O2 sensor and so on, they must reset the ECU before starting the engine and also every time when they change the condition. If they try different condition without resetting the ECU, it will be in a wrong mode.

If fuel pressure is under question, then they should follow the workshop manual to check the performance of fuel pump and pressure regulator. However, if your car was running fine before the service and if it was just clutch and timing belt service, then, I don't think they have touched any of the fuel pump or the regulator. Fuel pump is inside the fuel tank any way...

If they can make the car to idle, you can ask them to measure the intake manifold pressure. On the throttle body, there are four short tubes connected and #4 is the one connected to the manifold pressure sensor for ECU fuel Map. Just 'T' in there and you should see about 20 - 22inHg.
With analogue measurement, the needle should be dead steady. If not, you have timing issue.

Depending of the location of timing issue, it will show up on the compression check as well. However, if you have other issues on the engine, obviously, the compression test won't be conclusive enough to say that you have a timing issue. This is why I always carry out compression test before start of timing belt service and then after the valve clearance adjustment. After the adjustment, the difference between each cylinder would be smaller than the one measured before start of the service.

Hope your NSX will be back on the road soon.

Kaz

[Tom_]

You are not the first one to have problems with them, like the member that a diff locked!They've encountered a lot of unexpected issues whilst dealing with the car, and I suspect it's getting as frustrating for them as it is for me. They've been very fair about things so far.



After a cambelt service? They sure they haven't got the cam wheels out of alignment by a tooth? There was another NSX on here that had that problem.I'm 99% sure this isn't the problem - both from them testing manifold pressure, and also from the mechanic's description. Also, the initial problem, immediately post-cambelt-change rebuild was that it was running extremely rich - eye-stingingly rich. I didn't think that the timing being just out would do this?



If the fuel pump resistor is the problem, then you can bypass it by shorting the two female pins on the chassis loom side carefully.
This will force the fuel pump into high speed mode.

Under normal street driving condition, the fuel pump is in slow speed mode but at the time of engine fire up as well as above 4,000rpm with certain intake manifold pressure, the pump will operate in high speed mode.

Regardless of the fuel pump speed, the fuel pressure is always controlled at 3.5kg/cm2 ABOVE the intake manifold pressure by the pressure regulator.

So, if they bypass the fuel pump resistor by shorting the two female pins and still having the problem, then, I don't think it is the fuel pump resistor issue.KazHi Kaz

As you know, the problem we spoke to you about was that it was running very rich. The day after we spoke (by which time I'd gone to Le Mans) they found a problem with the connection to the fuel pump resistor - the terminals were corroded, and the wire was hanging on by a few threads. They resoldered the connection, and apparently things were much better. However, the car then had (or developed? Not entirely clear of the chronology) what has been described as a misfire, or rough running. This is the problem they're now trying to fix. Apparently bridging the fuel pump resistor pins largely clears it up, so they're working on the premise that the resistor was damaged in some way, during the soldering process. Hence another one has been ordered from Honda to test.




If fuel pressure is under question, then they should follow the workshop manual to check the performance of fuel pump and pressure regulator. However, if your car was running fine before the service and if it was just clutch and timing belt service, then, I don't think they have touched any of the fuel pump or the regulator. Fuel pump is inside the fuel tank any way...

If they can make the car to idle, you can ask them to measure the intake manifold pressure. On the throttle body, there are four short tubes connected and #4 is the one connected to the manifold pressure sensor for ECU fuel Map. Just 'T' in there and you should see about 20 - 22inHg.
With analogue measurement, the needle should be dead steady. If not, you have timing issue.

Depending of the location of timing issue, it will show up on the compression check as well. However, if you have other issues on the engine, obviously, the compression test won't be conclusive enough to say that you have a timing issue. This is why I always carry out compression test before start of timing belt service and then after the valve clearance adjustment. After the adjustment, the difference between each cylinder would be smaller than the one measured before start of the service.My understanding is that, upon testing the day after we spoke, the manifold pressure was OK and steady (thus indicating the timing is OK) and the fuel pressure was OK with the pins bridged. Not aware that a compression check has been done.



Hope your NSX will be back on the road soon.Me too, believe me. I'm really starting to get fed up.

[Sudesh]

I'm sure this has been checked but just to throw it out there, has the condition of the coil's been inspected? Especially the rear bank.


However, the car then had (or developed? Not entirely clear of the chronology) what has been described as a misfire, or rough running. This is the problem they're now trying to fix. Apparently bridging the fuel pump resistor pins largely clears it up, so they're working on the premise that the resistor was damaged in some way, during the soldering process. Hence another one has been ordered from Honda to test.

[Tom_]

I'm sure this has been checked but just to throw it out there, has the condition of the coil's been inspected? Especially the rear bank.I believe so, but I'm not 100% certain, Sudesh. I think they checked the coils after having (supposedly) fixed the resistor. If a new resistor doesn't solve things, I'll definitely mention it.


However, while it's possible that multiple things have broken while it's been with them, I'm working on the premise that the problem with it is a single issue that they've caused whilst doing the work on it. The engine was running beautifully prior to going in for --what I thought was-- routine work.

[Sudesh]

Worth a check Tom!

I have an NSX in at the moment for work, it had a timing belt change and plug change before it came to me, but the owner thought the car was a bit off and missfiring. After inspection I found that:

1: The front and rear bank coils were swapped
2: 2 of the coils were in bad shape

http://i77.photobucket.com/albums/j77/icongroup/JDMYELLOW/SAM_1755.jpg
http://i77.photobucket.com/albums/j77/icongroup/JDMYELLOW/SAM_1757.jpg

I replaced the 2 coil's with new ones and car is running beautifully no


I believe so, but I'm not 100% certain, Sudesh. I think they checked the coils after having (supposedly) fixed the resistor. If a new resistor doesn't solve things, I'll definitely mention it.


However, while it's possible that multiple things have broken while it's been with them, I'm working on the premise that the problem with it is a single issue that they've caused whilst doing the work on it. The engine was running beautifully prior to going in for --what I thought was-- routine work.