Chapter 7 with a Caterham SVT

[redursidae]

The old hose had many small cracks.

And the fixed hose installed.

 

Much less odor after a drive although still found a wet spot at the bottom of the  hose from hopefully a slightly loose clamp. We’ll see in the next drive.

 

And in case I was feeling that the list of needs was getting shorter I found it needs new engine mounts and a fuel level sender gasket.

 

are there any gotchas with replacing the engine mounts or will that be a straight forward process?

[redursidae]

I came home yesterday to a strong smell of fuel in the house. Found the Cat spilling fuel from the EVAP canister at the front and had overflowed a catch can underneath the intake. The car had sat with half a tank of fuel since I last drove it the day prior, and the tank didn’t have pressure.

This is the canister in the front corner. Hose marked is the one that was spilling fuel. There is a bottle down there that was full of fuel too.

 

This hose in the tank is connected to the “purge tank” port in the canister. Is this the main tank’s breather?

 

And the filler neck breather (?) is connected to the purge solenoid, which has a T going to the catch can that overflowed. It has the rollover valve near the wood pictured.

 

Would appreciate any suggestions on what to do about this. It seems to me part of the problem is the filler breather is connected to the purge solenoid, which is normally closed, and has no connection to the engine. That’s probably a good thing in this moment as I think I would have found fuel in the manifold. 

[Austin David]

My 2021 doesn't have an evap system at all.  Is there a local emissions requirement for it?

[redursidae]

Just now, Austin David said:

My 2021 doesn't have an evap system at all.  Is there a local emissions requirement for it?

Could you show me how yours is setup?

 

No requirement where I live so I’m ok getting rid of it. But it’s my understanding that these came with this canister setup. 

[Vovchandr]

I also removed all my evap system. If I recall it was just in place to begin with but not connected, but memory is vague at this point. 

[Austin David]

Any idea how fuel is getting from the filler all the way forward to your can?  From the photo I assume the evap line is coming from the very tip top of your filler neck, then plumbed forward to the evap can.  Then usually a purge valve between the evap can and your intake manifold. "fuel in the manifold" is clearly not ideal.  In typical operation I understand that the purge valve would open to pull vapors out of the canister, which USUALLY is not a big deal.  But if you're getting enough fuel in there to fill that canister and overflow into a catch can (then overflow THAT), something seems not right?  The fuel tank needs to have some ventilation -- fuel expands and contracts, and as you empty the tank something needs to let some air back in.  I'm pretty sure I have a vent in my filler neck up near the top, but I don't have a photo handy.  Either way, I'd want to be sure I understood why fuel was coming out of the tank and down that line; if you block or otherwise vent the same tube that's delivering overflow to your evap can, it will just deliver overflow to your floor or something.  

[redursidae]

My only guess as to how fuel could have made its way to the front is through slush when I last drove it, then maybe vacuum did something funny to start a siphon? But that's only a guess, I don't actually know. I filled the tank earlier this month to see how much it took and drove it to the nearest city, maybe some fuel made its way into the lines that day, but it certainly wasn't spilling over then.

 

I agree about the tank ventilation and evap function. What's throwing me off is that my tank has two vents, one in the center and one at the filler neck. I don't know if it's ok to vent both with a rollover valve, or tee them together, or cap one while leaving the other one open.

[JohnCh]

I was curious, so popped out my floor to take a look how my recent build is plumbed. The only vent is the one in the filler neck above the internal flap valve (shown roughly by the white line). The hard tube at point A connects to a rubber hose that loops around to the red rollover valve, then continues down to the bottom of the tank where it’s zip‑tied to the clamp rod (red line). From there, it follows the rod back up to the top of the tank and vents to atmosphere.

 

  

 

[redursidae]

Thank you John! This is perfect. Then I'll go ahead and copy this system and cap the other port on the tank unless told otherwise.

[CBuff]

@JohnChThat is the cleanest nether regions of caterham I have ever seen.  You might have shamed me into polishing more 

[JohnCh]

Just to add onto my earlier post, that hose next to the filler might act like a secondary vent. Although it enters the filler neck below the flap valve, if that's not particularly airtight, then air could escape through it and join the main vent system on the other side.  

 

@CBuff, I hit it with compressed air before taking photos  

[williamwashere]

You’re making me feel worse if all that took was some compressed air to clean!!

[wdb]

A fuel injected car is going to have a return line to the gas tank I believe? My car has Webers so I can't directly comment. I'm thinking of that line at the top of the tank.

 

The @JohnCh loop reminds me of what I rigged up on my car to reduce the gas smell in the garage. It's a looped hose coming off the vent port (with rollover valve) on the fuel cell. The exit is below the bottom of the tank. I believe the science behind the loops is that vapors will condense before making it all the way through. The fuel/vapors will be drawn back into the tank as air is pulled in to replace the fuel being spent on fun things.

 

 

Edited Wednesday at 01:31 PM by wdb

[redursidae]

Thank you @wdb . That does make sense regarding the other line at the tank being for a fuel return. The SVT doesn't have a return line or a pressure regulator*. Instead the pressure is controller by the ECU as a return-less system.

 

*: The regulator on these systems tends to be inside the tank, but I haven't been in there or found information on it. Apparently it may not have one.

 

I went ahead and looped the line as in John's picture. Hard to take a good picture, but the breather goes around and behind the tank up to the rollover valve, then over the filler and back down next to the tank. 

 

and capped the other line, but this doesn't feel like a permanent solution. It's a vacuum cap and I feel that's going to crack and leak. Open to suggestions as to what to use on this for a permanent fix.

 

As a note it was definitely this other port above that was sending liquid fuel. When I removed the line it still had fuel in it, and tilting the line at the front of the car dropped more fuel out. 

[Austin David]

If you click around a lil you'll find some pics and writeups about the other setups -- @JohnCh and I have traded a few, for instance.  Your setup is different than our Duratec-based systems.  For the sake of future readers, could you post a couple more photos while you have it open, and of course share your experience when it's all sorted?

[redursidae]

Yes, will do. I haven't had a chance to drive the car yet, but this weekends autocross will be a good stress test.