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Fuel pump bypass

missnancy

missnancy

Regular Contributor
"I have a quick question as I

"I have a quick question as I sit here at 3:00 am coughing my lungs out.
My engine is a 1970 350 which has a combo of Crusader and Pacer parts. For the younger members the pacer configuration was made for Pacemaker and Alglas boats.
I have rebuilt the engine and when putting on the new fuel pump I find a extra tube, after a bit of quick research I find it is the bypass should the diafram fail. Where the hell does this go to? I mean obviously you dont want it to be draining into the bilge. I have no where to hook it on the carb which is what one fella suggested. On the positive side of things I am ready to put the engine back into the boat other then this.
Thanks in advance! Paul in Maine"
 
"It goes to the carb so fuel l

"It goes to the carb so fuel leaking past the diaphragm gets burnt inside the motor instead of going to the bilge or oil pan. If there isn't a fitting on the carb or flame arrestor, you could make up a bracket to aim it in that direction. I've seen flame arrestors with a hole drilled in them for the hose.

Jeff"
 
"Jeff,
Sounds like the only s

"Jeff,
Sounds like the only solution as there is no where to hook it in otherwise."
 
"Paul, I am wondering if ther

"Paul, I am wondering if there are probably replacement parts in these areas which makes me think that if the pump or carb is original , then that's where the difference comes in as one of them was not made for the newer application. BUT if both are new, shouldn't they be fitted with the same options particularly if they would need USCG approval OR is it an automotive carb?"
 
"Not sure here but it sounds l

"Not sure here but it sounds like if thats a bypass fitting it should be capped off unless your running the fuel through it bypassing the pump. Just my guess, but I can't imagine an open line on a bypass side routed to the carb.......don't sound right to me."
 
"Tailspnr,
As was explained t

"Tailspnr,
As was explained to me the bypass is to let the gas go somewhere other then into the oil pan should you rupture a diafram. So capping it of would not be the best way to solve the problem.

Al, The carb is a ruman 1967 Rochester 4jet, the predeseser to the quadrojet. An unfortunatly it has no place to hook into. Can you say old technology?
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"Ahhhhh...........well that ma

"Ahhhhh...........well that makes sense I guess. I assumed the bypass was in the event that you wanted to use an external fuel pump and bypass that one. But in that case I assume you'd just pull the fuel line and reconnect elsewhere.


Just out of curiosity, where would the fuel go if the bypass fitting wasn't there and you ruptured a diaphragm?"
 
"Paul, If you look at that av

"Paul, If you look at that avatar under my name ....I LOVE OLD TECHNOLOGY....(1925 Henderson)"
 
"Does the dog travel with you

"Does the dog travel with you all the time? We have 2 golden retrievers and 1 would go every where...the other is a lunatic and hops over the seats in the car 20 times in a few miles. Since that experience, they both stay home. But our #1 dog is now 14 plus...She sleeps 75% of the day.

I have seen SO many dogs out on the water...many just jump in and swim around and others just hang out. Is a USCG vest required for them?"
 
"paul

what carb sits atop t

"paul

what carb sits atop the engine, a 4G?

most aren't too hard to drill and tap, to insert a fitting if you want a clean look. Another approach is alluded to by FastJeff; I'd drill the flame arrestor only if you have a threaded hose barb that would mount in that hole (probably a 90 degree fitting). I wouldn't drill thru the 'breathing area' of the arrestor. You need a direct path into the venturi area of the carb."
 
"Al,
The Lab likes to ride bu

"Al,
The Lab likes to ride but can't be left alone in the car as she gets extremly hyper. I came out of lowes one day and thought I was hearing a car alarm but it was her jumping on the horn over and over again. On the boat she is better., and no I don't think there is a requirement for life jackets for dog's but I am not positive of this. I do know that she really hates the thing.

Makomark,
I went with drilling the flame arrester and hope to finish it up tonight. I will post a couple pictures when its done.
Have a good weekend everyone!"
 
"Guy's,
Here is what I di

"Guy's,
Here is what I did to solve my bypass problem.
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flame arrester modification"">
286913.jpg
flame arrester modification 2
 
Paul

great pics....nice to

Paul

great pics....nice to see an old 4G still running.

Looks like a reasonable mod. Can't tell from the picture but I'm make sure there's no leak path under the retaining nut on that hose barb.
 
"Makomark,
I was thinking of

"Makomark,
I was thinking of useing 5200 under the nut, your thoughts? Or would I be better off with making up something out of gasket material? I hope to drop the engine in this week or early next week. Going to be a late season but so be it.

Jeff, Good luck with the surgery!

Paul in Maine"
 
"Paul-
i don't have any i

"Paul-
i don't have any idea how 5200 reacts to the gasoline vapor rich environment atop a carb. Also unsure what its max temperature is. I'd look up its data sheet at the 3m www site before going down that path.

Other options could be Permatex #2, #1, or some epoxy. I'd also cut the "inside" end of the fitting off, flush with the nut, to minimize any air flow irregularities going into the carb. (that things sticks out a good ways.)"
 
"One data point. My Prestolit

"One data point. My Prestolite distributors, which are ignition protected, say to use RTV to seal any exit wire gaps with the housing. RTV, although a bad choice to hold with gasoline, is good in that it does adhere well to most surfaces, and won't crack with motion or heat. I'd use ultra copper or ultra black. There is not much fuel in that area that would concern me. That site tube should sit for a decade without any gas in it. I would take Mark suggestion and cut off the inside a bit. It may cause some air pressure in the hose at that angle."
 
"I was thinking the fuel vapor

"I was thinking the fuel vapors in that area, especially after an hour long cruise up the river on a 90+ degree day...

Didn't think of the pressure difference due to geometry - don't think that would have any impact to the pump's operation....more that the "shadow" below it couse cause all sorts of anomolies on a 4G, with its 'forrest' of vents and ports..."
 
"Paul, The "overflow"

"Paul, The "overflow" line from the fuel pump to the carb. should be clear plastic. You have to be able to see if fuel has entered the tube when checking oil etc. Since the fuel pump is dual diaphragm the engine will continue to run normally. Fuel in the tube will be the only indication that a pump diaphragm has failed & you are running on the "back up" diaphragm."
 
"Lou,
Thanks' I picked th

"Lou,
Thanks' I picked that part up on other posts but it is always good to be reminded."
 
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