CSR: Fuel Pump keeps blowing fuse.

[Croc]

19 hours ago, pethier said:

What is this device just forward of gas tank?

 

 

Two options

 

One, it says Weber and my carburetors are always in front of my fuel tank (I don’t drive VW beetles). 
 

However, I really think the answer is two, a nozzle for the onboard fire extinguisher.  Weber makes those too.  

[Croc]

19 hours ago, pethier said:

Fuel pump and gauge sender bulkhead.  I can't believe how tiny these wires are.

It’s only a sub 15 amp circuit.  Not a lot of current needed to drive a small pump like this. 
 

For the size of engine and hp this is the minimum you can get away with.  Keep this in mind if you ever decide to up hp via a new tune.  Otherwise this pump will lean you out. 

[7Westfield]

2 hours ago, Croc said:

Two options

 

One, it says Weber and my carburetors are always in front of my fuel tank (I don’t drive VW beetles). 
 

However, I really think the answer is two, a nozzle for the onboard fire extinguisher.  Weber makes those too.  

I wouldn't think it's a fire nozzle, with that hose barb on the side.

My guess would be some sort of vent gizmo for the fuel tank

[pethier]

4 hours ago, Croc said:

It’s only a sub 15 amp circuit.  Not a lot of current needed to drive a small pump like this. 
 

For the size of engine and hp this is the minimum you can get away with.  Keep this in mind if you ever decide to up hp via a new tune.  Otherwise this pump will lean you out. 

Not planning on going for more than 260 hp in the near future.

[Croc]

7 hours ago, 7Westfield said:

I wouldn't think it's a fire nozzle, with that hose barb on the side.

My guess would be some sort of vent gizmo for the fuel tank

 

Interesting thought.  Its the standard tank installation and I never had a vent like that on my CSR260 - clearly its a later modification if it is a vent.  

[7Westfield]

fuel pressure regulator?

I found pics of similar units on Westfield forum

Edited July 3 by 7Westfield

[S1Steve]

54 minutes ago, 7Westfield said:

fuel pressure regulator?

It is…

[pethier]

1 hour ago, S1Steve said:

It is… [fuel pressure regulator]

Just to educate my often-uninformed self:

 

Does the CSR 260 use the constantly-circulating method of fuel delivery?

 

If so, then if this is indeed a fuel pressure regulator, this device is located on the return line to the fuel tank?

 

On my Birkinized Caterham, the fuel pressure regulator hangs directly on the outflow end of the fuel rail of the Hayabusa injection.

 

On my actual Birkin, the fuel pressure regulator is directly aft of the cylinder head.

 

In all of these cases I expect the result is schematically the same.  The advantage I see to the location back by the tank is that the device would not be subjected to the higher temperatures present close to the engine.  

 

The possible disadvantage would be inaccessibility for adjustment.  This would be inline with Cosworth's apparent ethic of "don't mess with our setup".

 

[Scott_]

 

My guess on the part with the weber stamp is a fuel pressure regulator.

 

Scott

 

 

 

Edited July 3 by Scott_

[pethier]

The fuel pump from Rimmer is here.

I welcome any advice on how to install it without having a truly epic fire.

I suppose I should siphon out all the fuel that I can out of the tank so that the assembly is not completely dripping when I withdraw it.

[pethier]

On 7/1/2026 at 11:13 PM, pethier said:

Fuel pump and gauge sender bulkhead.  I can't believe how tiny these wires are.

 

Is there a way to unplug these electrical connectors from the cover plate?

 

Trying to withdraw the assembly from the tank with these wires all connected sounds like a nightmare.  I don't want to break anything, so I could use some guidance.

[Croc]

Let’s start with first principles - disconnect the battery.  
 

Then disconnect those electrical connections - they are a friction type based on what I had on my CSR.  But the easier option is trace the wires down the cable until you see an easy click plastic connector.  Uncouple there.  
 

Then start to cut around what I suspect is blue hylomar or similar sealant - you want to lift this round metal cover plate out vertically eventually. The actual fuel pump is attached underneath. 
 

Then unscrew the cover plate fixings.  
 

Refer back to the photos of the complete unit removed from my old post to help you visualize.  
 

That’s enough for now.  No point getting too far ahead of things. 

[pethier]

On 7/7/2026 at 7:07 PM, Croc said:

Let’s start with first principles - disconnect the battery.  
 

Then disconnect those electrical connections - they are a friction type based on what I had on my CSR.  But the easier option is trace the wires down the cable until you see an easy click plastic connector.  Uncouple there.  
 

Then start to cut around what I suspect is blue hylomar or similar sealant - you want to lift this round metal cover plate out vertically eventually. The actual fuel pump is attached underneath. 
 

Then unscrew the cover plate fixings.  
 

Refer back to the photos of the complete unit removed from my old post to help you visualize.  
 

That’s enough for now.  No point getting too far ahead of things. 

With my experience with another Caterham gas tank, I was sure to put in some longer bolts to catch any possible keeper ring inside the tank.  Turned out this tank has none: the threads are provided with rivnuts.  I still suggest that procedure; you never know...

 

OK, the assembly is out.  If I thought the wires on the outside were tiny, the ones leading to the float assembly are microscopic.

 

 

[pethier]

Now I need to know how to get this thing open without breaking anything.

 

[pethier]

On the CSR260.  At the bulkhead on the top of the tank, the white wire transitions to a red wire. As that 5-wire bundle approaches the connector, the red wire ends and is covered up.  The connector only has four positions used.  There is no wire on the upstream bundle to supply this part.

 

I believe it is a low-fuel sensor.  I don't even know if the CSR260 has a use for this.  Previous users have apparently gotten along without it.

 

I suppose I can just leave it there.  If I ever find a reason to connect it, I won't have to pull this assembly again.

 

 

Edited 21 hours ago by pethier

[pethier]

Wire descriptions leading to fuel pump and fuel-level components                                
                                
chassis side of connector     >     tank side of connector     >     bulkhead outside tank     >     bulkhead inside tank     >     destination 
                                
yellow with green stripe     >     cream or white bad insulation     >     cream or white      >     red     >     pump
                                
fat black      >     thin black with crimp splice     >     black     >     black     >     pump
                                
green     >     lavender     >     lavender     >     tan     >     float
                                
thin black     >     thin black     >     black     >     black      >     splits; one to float and one to low-fuel sensor
                                
none     >     red not connected. taped up end     >     red     >     white     >     low-fuel sensor

[pethier]

Now that I have this assembly out on the bench, I can investigate the wire bundle from connector to bulkhead.  These little wires seem to be running loose, covered by a loose plastic sleeve.  I will have to slit this sleeve so I can inspect all the wires.

 

The problem is probably not a short upstream of the connector, since I see damage to the cream/white wire close to the downstream side of the connector. 

 

Tomorrow.  Now I'm going to watch Messi and team play some football.

Edited 6 hours ago by pethier
Rush to watch the footie caused some things that needed fixing the next morning.