Order of Devices in the Fuel Line

[roadnsky]

It is a box of sheet metal construction that fits snugly over the flame arrestor (a brass (I think) porous grid "filter" thingy) and (above that) a foam sponge (replacing the original which eventually disintegrated).

Don-
That is most certainly not a "stock" setup and I'm not even sure if it'd pass the Coast Guard spec.
"Arrestor should be kept clean to prevent contamination from propagating a flame."
Just the fact it is a sponge would be a concern for me.
At the least, I would think it is affecting your fuel mix.

You may want to add it to the list to "upgrade" that setup while you're going through your fuel system end-to-end.

[campbdon]

Order of Devices...

Spoke with the PO, who says it was his attempt at adding an air cleaning function in front of the arrestor. I plan to replace it with the properly sized housing for arrestor only, or at the very least remove the sponge.
Thanks guys!

[JOHN COOKSON]

Don-

"Arrestor should be kept clean to prevent contamination from propagating a flame.".

Removing the element from the back flame arrestor and cleaning it in solvent was a yearly matience procedure for me. The element is a good air filter by itself and does not need a "booster" filter.

ex TRUE GRIT

Edit: Sharp eye Jerry.

[zellerj]

Carb looks clean.

[roadnsky]

I am planning to replace all the fuel lines (the run from the tank to the pump was only 1/4" ID, not the recommended 5/16") with the USCG approved stuff. If water is not suspected as an issue, rather than adding a water/fuel separator, is there anything "wrong" with moving the coarser filter in front of the pump and adding a finer one after that (either before or after the pump)? If I decide to get the separator must it mount on a bulkhead? I don't see where on the engine block that could attach?

Don-
I think we got a bit off-course (but for a valid reason) and I want to make sure you got the answers to your main questions...

"If water is not suspected as an issue, rather than adding a water/fuel separator, is there anything "wrong" with moving the coarser filter in front of the pump and adding a finer one after that (either before or after the pump)?"

No. In fact that is preferred to your current setup.

"If I decide to get the separator must it mount on a bulkhead? I don't see where on the engine block that could attach?"

Yes, that is the typical setup and adding the Racor would be an improvement to your current system IMHO.
While you're at it, maybe add a fuel pressure gauge too as Dave mentioned?
(Attached is a pic of my setup. Although my Facet is also on the bulkhead for other reasons)

[capnward]

Seems to me adding a sponge on top of the flame arrestor is a bad idea for three reasons:
1. It restricts airflow, performing the function of a choke to some extent.
2. If the engine does backfire, and a flame tries to emit the air intake, it could catch the foam sponge on fire. Or partially melt it, causing more air restriction.
3. cleaning the flame arrestor is easier than cleaning a foam sponge. The foam may absorb water in the air, further choking the engine.

You might experiment with removing the sponge while it is running to see what difference it makes. If you have a vacuum gauge, check that at the same time to see how much it may be restricting airflow. Let us know what you find. Then leave the sponge box off. I think the flame arrestor is all the air filter an A4 needs. The PO was being too clever, though well-meaning. Let the engine breathe.

[campbdon]

Order of Devices...

I have already removed the sponge and reverted to original arrestor and it's housing. The modified version was indeed a homemade sheet metal enclosure in which the original arrestor+sponge+housing was nested. Now I'm back to discover what's actually preventing my engine from starting. I think I'll open a new thread under Troubleshooting for that.
Thank you all for your helpful suggestions. My engine environment is steadily improving.
DonC

[scratchee]

Sorry if I missed it, but what sort of starting issues are you having? What are the symptoms? Last year I did some similar work to what you are doing, including adding a water separator and polishing filter, due to extremely long cranking required to start and sometimes no start at all. After all is said and done, I'm pretty sure the problem was an air leak at one of my fuel lines, specifically at the squeeze-bulb primer that I removed from the system. I now have a very reliable start.

[campbdon]

May I ask one more related question? I'd like to add a second fuel shutoff to the chain. Already one at the tank, so I thought one near the carb?
If the secondary shutoff became closed would the backpressure faced by the pump be harmful?

Tank -->FS1 --> H20/filter -->F1 -->Pump-->F2 -->FS2 -->FPG --> Carb

FS1 = fuel shutoff primary
F1 = Filter1 (coarse)
F2 = Filter 2 (polishing)
FS2 = Fuel shutoff secondary (to be added on bulkhead)
FPG = Fuel pressure gauge (to be added on bulkhead)

Also, how about some sort of manual drain petcock to mostly drain fuel from the lines before disconnecting hoses? Or would that be another point of failure?
Thanks
DonC

[ndutton]

I have a manual shut off valve immediately ahead of the carb in addition to the USCG required valve on the tank that's near impossible to reach or at least it's a PIA. A benefit you didn't mention is with the valve next to the carb always closed when the boat is unoccupied it's a safeguard against an uninterrupted fuel leak if the carb's float valve is stuck open. That was my experience and why I added the valve.

As for concerns over dead heading the pump with the valve closed, it's no different than the carburetor float valve closing so in my opinion, a non-issue.

[campbdon]

I believe I've improved my fuel delivery system considerably with all your help.
Have added a polishing filter, fuel pressure gauge, and secondary shutoff (before carb) . Next step is to add water/fuel separator. Most advice I've read has it as the first element in the chain, however as I already have a coarse filter and polishing filter (10 microns) as well as fuel hose routing challenges in the engine compartment and bulkhead what if I put the separator AFTER the pump and polishing filter instead, or might the polishing filter foul preventing any water content reaching the separator ?
Such as one of the following...

Tank -->FS1 --> F1 -->Pump-->F2 -->H20/filter -->FPG -->FS2 --> Carb
Tank -->FS1 --> F1 --> H20/filter -->Pump-->F2 -->FPG -->FS2 --> Carb


FS1 = fuel shutoff primary
F1 = Filter1 (coarse)
F2 = Filter 2 (polishing)
FS2 = Fuel shutoff secondary (to be added on bulkhead)
FPG = Fuel pressure gauge (to be added on bulkhead)

Thanks for any feedback
Donc

[Peter]

Don,

Fuel-water separator first. If there is water in the fuel it will make a mess of any filter that is not designed to deal with water.

Hope that helps,

Peter