Trojan Boat Forum

This has been discussed before but asking opinions on my solution. I have new carter fuel pumps for my 318s and they have a hose barb that would be to allow fuel to exit above the diagphram if the diagphram were to fail. At present my intention is to connect this vent to a T in the Positive Crankcase Ventilator vacum line, ergo the gas would go into the engine safely and not spill into the bilge.

The diagphram upper void holds a vacuum so should not effect the PCV function. I have tried to come up with a way to dump directly into the breather but have not yet come up with a way to do it.

Comments on my solution?

Unless I'm mising something here piping that line to the crankcase would not be a good idea. It would be creating an explosive enviroment should the engine backfire through the PCV. I know, not suppose to happen with a PCV valve, but how many other things are not suppose to happen but do. Also if a pump did rupture and started pumping gas into the crankcase you would start overfilling the engine with gas and diluting the oil changing the viscosity to a very thin mix. A hard working engine running on little to no oil pressure spells dollars in my book. In the fall I pour a little gas in the oil of my lawnmower and run it for about 90 seconds to flush the crankcase. The oil comes out thinner than water.
I would endevour to get them plumbed to the correct location on the carbs.

TC is absolutley correct!

The fuel from the fuel pump, should a rupture occur, needs to go the the carb. Do not "T" into the pcv system.

if you dont want to purchase new with the fitting already installed(they are expensive so i dont blame you) an option would be to drill in the top of the flame aresstor and install a 90 degree barb fitting and on the inside affix a backer to it. then you will have the tubing routed to the correct place in the case of a problem

First, regarding the crankcase, I am not piping it to the crankcase. the PCV valve operates with a vacuum on it and is a one way valve in the valve cover flowing to manifold vacuum, The "T" would be installed near the carb which if fuelpump diaphragm were to rupture the fuel would be sucked into the base of carb and ergo combustion chambers, engine would flood but no external fire.

Expense is not an issue. the fuel pumps have the barbs built into them. I have not been able to locate a barb with nut for mounting into a hole in spark arrestor (which is what I would prefer anyone know of one let me know) another issue is that the backing nut for this type of assembly would have to be drilled and pinned on as it could come loose and drop into the engine. Bad thing. I cannot braze or solder it to the spark arrestor as it is made of stainless. The crankcase breather (not the PCV system) is mounted in a bracket and butted up against the outside of the spark arrestor by Chrysler, ergo any venting crankcase gas goes through the spark arresting fins, any crank gas would not be dangerous here. But I want to be sure any liquid fuel that might eject from bad fuel pump goes into the carb and intake so no boom.

Thank you for your comments,

i offered a option on the information i was give i.e your post. didnt mention anything in there about looking for the barb with nut that you need. that might have been helpful. maybe thats what you could have asked about. sounds like if expense is not an issue to you then why not buy the correct part and not rig it.

note to self: maybe i shouldnt offer suggestions to others that ask

Hooking it up to the PCV hose is not a good place . It should not have vacuum on the line . The others are correct

One more time.

Not trying to criticise you but...If there is a backfire, it will come up through the carb. Remember, the spark arrestor is to arrest flames from exiting up and containing it within the carb.

In your situation/idea, you assume that any purged fuel, from a ruptured diaphram can be drawn into the top of the carb, via crankcase breather hose. This is not a good idea, imagine that you're cranking the engine because it won't start, uh, fuel pump has ruptured and the carb is not getting gas, but...there is enough fuel left in the bowl to try and start and run with a lean condition. This lean condition will invariable cause the engine to cough and sputter while you're pumping the throttle trying to get her going. Caugh and sputter will most likey cause a backfire...and guess what?? That fuel laying on top of the choke and throttle plates, which is not drawn into and below the plates, is now on fire! Not good and has air to fuel the fire further.

By using a vacuum port below the thottle body or, a fitting which draws fuel back into the fuel bowl, for a return of liquid fuel to be burned, is what is engineered. Especially in a marine engine, contained in a hull.

You can do it...or you can do it right!

If money is not the issue, and shouldn't be with safety items, then go buy a new flame arrestor for the carb with the fitting already in it for the fuel pump overflow hose to attach to. Then it will be just like the factory intended it to be.

If money is not the issue, and shouldn't be with safety items, then go buy a new flame arrestor ($50 each) for the carb with the fitting already in it for the fuel pump overflow hose to attach to. Then it will be just like the factory intended it to be.

Thank you tad too much. That is what I was looking for. Now to find a spark arrestor as you described. Any knowledge of who makes it or where to get it.

Not offended by any of your comments that is what I asked for and thank you. Direct the line to the spark arrestor as the best solution.

To be clear where can I get:

1: a barb that I can make to the arrestor?

2: Arrestor with hose barb made on it? ( Note the original pumps both have a barb on the top of fuel pump but was blanked off by a rubber nipple, the manufactures Chrysler and Trojan saw fit to just plug the barb, however plugs were rotten and if the pump had failed the bilge would have had raw gas in it. Both engines were exactly the same, so I intend to improve upon the manufacturer)

If that cannot be done I do not see why my solution will not be safe and work.

The PCV does work as a one way valve vacuum (Carb) and prevents backfire to crankcase if one should occur obviously there is less vacuum at high speeds then at idle; see for PCV operation:

http://www.jalopyjournal.com/forum/show ... hp?t=61376

How are your 328's plumbed for this situation?

Just determined through talking with Bob at Beacon and checked, they have the arrestors with hose barb. He said and it looks like his description that the fuel pump venting hose is just held up to the outside of the flame arrestor the same as the second crankcase breather hose. His suggestion is make a bracket the fixes the end of the fuel venting hose against the spark arrestor is the same as the arrestors with a barb. Which is what I will do.

Thanks all for various suggestions, BTW Bob says the vacuum at the PCV would be too great for the fuel pump and not good.

Just holding the vent hose to the out side of the arrestor is not good enough .It needs to set out so if it was have fuel come out it would only end up on the inside of the arrestor on leaking on the intake .

Even better Most marine carbs have a port for this hose to go to

kinda what I thought but the ones at beacon look like they don't go in. I have marine carter afbs and i do not see any port ot put it too.

Gonna look again may be able to drill into the air horn somewhere and press a nipple in or thread for a threaded barb.

This has been discussed before but I cannot find it on our site. I recall someone talked of a kit to do it.

Thanks Paul

This was brought up before , A few years back I believe . I don't remember for sure but I believe there was a kit ?