Fuel pump fuse blows at 200km/h

[Dimer]

Last Sunday I was at the track around and at around 200km/h the fuel pump fuse blows. We replace the 15A for a 20A, but the same thing happened. We just replaced the OEM fuel pump for the Walbro.

Does anyone know what could be the problem?

 

[comtec]

All i can do is guess. Could it be that the pump is trying to draw too many amps for the size of the wiring? The walbro can draw a lot more amps then the factory pump and that's why a lot of people with other cars upgrade the wiring and add a new relay. Be careful as the blowing fuse could be your warning of worse things to come if you don't do something about it. Usually not a good idea to add a larger fuse to OEM circuits, better to fix the problem.


Mike

 

[spider2k]

are you using the stock wiring? most vendors recommend upgrading the fuel pump wiring to a larger gauge wire , relay, and fuse to accommodate the extra current draw of the aftermarket units. this may or may not be your issue but by bypassing the oem circuit and making your own it could solve the problem.

ryan

 

[RYU]

Assuming you don't have a short then +1 on both of these ^^

Upgrade the wiring and toss a relay in there and that should solve your problem.

 

[Briank]

Fuses blow when there is an overload. My guess is you have pinched wire.

 

[goldNSX]

Be careful as the blowing fuse could be your warning of worse things to come if you don't do something about it.

+2 as his car is supercharged.

 

[Gerard van Santen]

Fuses blow when there is an overload. My guess is you have pinched wire.

But why does the fuse blow ONLY at full load? (+120 mph). A pinched wire should blow earlier, perhaps as soon the key is switched on. Or is this wrong thinking? The problem is, that it is impossible to test it on normal roads

The fuel pump wiring is already thicker because of the upgrade to the Comptech Compressor.

 

[pgilliam1]

But why does the fuse blow ONLY at full load? (+120 mph). A pinched wire should blow earlier, perhaps as soon the key is switched on. Or is this wrong thinking? The problem is, that it is impossible to test it on normal roads

The fuel pump wiring is already thicker because of the upgrade to the Comptech Compressor.

1) Not "impossible" to test on normal roads :biggrin: -be safe.

2) The wiring from the power source to the fuse panel may not have been upgraded.

 

[Dimer]

I've ordered the 'fuel pump power distribution kit' from SoS. It will most probably arrive next week. I hope this will be the solution!

 

[comtec]

I've ordered the 'fuel pump power distribution kit' from SoS. It will most probably arrive next week. I hope this will be the solution!

Have you ever replaced or repaired the main relay? Make sure the G403 ground is not loose, it's located in the center of the rear bulkhead.

Mike

 

[Gerard van Santen]

Have you ever replaced or repaired the main relay? Make sure the G403 ground is not loose, it's located in the center of the rear bulkhead.

Mike

Hi Mike,
The main relay of Dimer's NSX is serviced and resoldered.

 

[comtec]

Hi Mike,
The main relay of Dimer's NSX is serviced and resoldered.

Cool, that's just a couple more things i thought of. Do you know if the walbro ground connects to the same location as oem (G403)? Thought maybe it could have been left loose when it was relaced.

Mike

 

[Gerard van Santen]

Cool, that's just a couple more things i thought of. Do you know if the walbro ground connects to the same location as oem (G403)? Thought maybe it could have been left loose when it was relaced.

Mike

You had problems yourself with the Walbro. What did you do to fix it and what was the cause of the problem?

 

[comtec]

You had problems yourself with the Walbro. What did you do to fix it and what was the cause of the problem?

No i don't have one that's why i wasn't sure where they ground them.


What puzzles me is that it happens at high speed only. I would think the fuel pump would draw more amps under higher rpm which you should see earlier. It could be because at higher speed the engine is at a higher rpm for a longer period of time and the sustained drain becomes too much i guess. Do you know what rpm you were at when it happened? You could replicate that in lower gears on the street.

If it were truly speed dependant, i wouldn't rule out the SRS which is on the same fuse.

Mike

 

[Gerard van Santen]

No i don't have one that's why i wasn't sure where they ground them.


What puzzles me is that it happens at high speed only. I would think the fuel pump would draw more amps under higher rpm which you should see earlier. It could be because at higher speed the engine is at a higher rpm for a longer period of time and the sustained drain becomes too much i guess. Do you know what rpm you were at when it happened? You could replicate that in lower gears on the street.

If it were truly speed dependant, i wouldn't rule out the SRS which is on the same fuse.

Mike

The duration at hi RPM may be responsible for al lot of stress on the wiring. That is why Dimer has ordered a wiring upgrade set from SOS. It is difficult to replicate the same situation in lower gears on the street. That means, that he has to stay in first gear (for example) for at least 20 seconds. I don't think the neighbourhood would appreciate that (speed limit, race exhaust and lack of road space)

Or he has to try it on the highway. That is 70 mph in second gear for a period of time (at least 20 seconds). That is also a non option because of the loudness. In no time the traffic police will be Dimer's 'best friend' :biggrin:

The first opportunity to test is june 17th on the Zandvoort Racetrack at the SuperLap (A Time Attack event). But probably he will blow his fuse again at the end of the straight if he hasn't solved this problem before the event