youll enjoy these random-dying stories!

Jon March

Member
So my car died randomly a few times this past summer "shakedown" season -

Worked fine in Celina - but in Port Clinton, a new thing happened - started starving for fuel, and then quit - wouldnt start. Couldnt figure out what happened - plenty of gas, was working fine, then suddenly starved out.
Some of you may know that rather than install an inline electric fuel pump to force fuel in case there was vapor lock, I took the advice of Gord Souter, who recommended a simple manual "primer bulb" from an outboard motor fuel line. Fuel flows thru, and prevents accidentally leaving a fuel pump "on" that could overwhelm the mechanical fuel pump, etc. Anyway, I installed it in the (ethanol-proof) rubber fuel line under the footboard, ...behind a trap door under the passenger side rubber mat.
So it occurred to me to open the trap door and take a look: lo and behold, the black rubber primer bulb was collapsed- sucked flat!: the manual pump on the motor was clearly doing its job "asking" for fuel... but something was not delivering it...and the bulb was the perfect visual aid to see that! ( thats another great point about the primer bulb!)
The fuel tap was open...the fuel filter flowed...the only thing left was the 12VDC fuel shutoff-valve.
It "seemed" to be clicking,,,but now it just wouldnt pass fuel! So I bypassed it with a double ended barbed brass coupler...and good to go!

John Bevins mentioned awhile back that the correct location that the factory derives 12v for the magneto is at the brake light switch. So i need to check to see if that supply connection is "100%", or if its funky - dont want to buy a fuel shutoff if not necessary.

>>> Have any of you folks ever has this happen?: the fuel shutoff valve works for a time, then after awhile shuts off on its own when you're out on the water?
>>>.Do the coils or connections in these eventually become "weak" or corroded?, allowing the valve to shut off and strand you?

---------------------------------------------

Stranded a different way! #@

This one was much more abrupt - driving along at 1/3rd throttle on the water...Dashboard suddenly goes dark and the engine stops. Turn the key. Starts up and continues fine, again wiothou problem for a sew more days.
Then it happens again - lights go out, car instantly dies!

I found the answer - do you have a guess as to what it was??
 
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Jon March

Member
Youre gettin very warm-but wasnt loose wire at the keyswitch....
Guess again? - PS: Battery and regulator/rear-starter connections were tight as well...
 
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lelms

Gold Subscriber
So my car died randomly a few times this past summer "shakedown" season -

Worked fine in Celina - but in Port Clinton, a new thing happened - started starving for fuel, and then quit - wouldnt start. Couldnt figure out what happened - plenty of gas, was working fine, then suddenly starved out.
Some of you may know that rather than install an inline electric fuel pump to force fuel in case there was vapor lock, I took the advice of Gord Souter, who recommended a simple manual "primer bulb" from an outboard motor fuel line. Fuel flows thru, and accidentally leaving a fuel pump "on" could overwhelm the mechanical fuel pump, etc. Anyway, I installed it in the (ethanol-proof) rubber fuel line under the footboard, ...behind a trap door under the passenger side rubber mat.
So it occured to me to open the trap door and take a look: lo and behold, the black rubber primer bulb was collapsed- sucked flat!: the manual pump was doing its job "asking" for fuel... but something was not delivering it...and the bulb was the perfect visual aid to see that! (SO thats another great point about the primer bulb!)
So, the fuel tap was open...the fuel filter flowed...the only thing left was the 12VDC fuel shutoff-valve.
It "seemed" to be clicking,,,but now it wouldnt pass fuel! So I bypassed it with a double ended barbed brass coupler from the fuel line...and good to go!

John Bevins mentioned awhile back that the correct location that the factory derives 12v for the magneto is at the brake light switch. So i need to check to see if that connection is 100%, or if its funky - dont want to buy a fuel shutoff if not necessary.

>>> Have any of you folks ever has this happen?: the fuel shutoff valve works for a time, then after awhile shuts off on its own when youre out on the water?
>>>.Do the coils or connections on these eventually become weak, allowing the valve to shut off and strand you?

---------------------------------------------

Stranded a different way! #@

This one was much more abrupt - driving along at 1/3rd throttle on the water...Dashboard gsuddenly oes dark and the engine stops. Turn the key. Starts up and continues fine for a couple days.
Then it happens again - lights go out, car instantly dies!

I found the answer - do you have a guess as to what it was??
 

lelms

Gold Subscriber
when I bought my amphi 30 years ago, it did not have a fuel shutoff. I've never seen the reason for one. It just seems to be one more thing to malfunction.
 

Jon March

Member
Ed Price made this comment awhile back, and a few others seem to agree. Others dismiss it.
As long as its reliable, it seems very smart. But read this:

"The float valve in the carburetor bowl
should shut off the fuel flow and eliminate siphoning. The exception is when you
park on a steep grade, and the fuel level in the float bowl is not level. The
slope of the car puts the tank at an even higher level than the carb bowl, and
the float might "think" that the bowl level needs replenishing, so it opens a
bit. Fuel flows by siphon effect, and never stops because the fuel is running
out the side of the float bowl and into the manifold. This might stop when the
intake manifold fills with gas, but then remember that the intake manifold drain
tube (that funny little pipe that goes nowhere) will drain the intake manifold
into the bilge. Absolute worst-case scenario is gas in your oil pan, gas in any
cylinder with a partially open intake valve, gas in the intake manifold, about
15 gallons of gas in the bilge, and an empty gas tank."
 

lelms

Gold Subscriber
Ya I get that theory. I wonder if anyone has ever had gas siphon to the carb, filling the manifold and worse. To me, it is kind of like the concept that tubeless tires will roll off the wheel in a hard turn. I've run tubeless for 30 years, radials for 10. Again, no problems. I have never heard of any amphi having their tire come off the wheel because they were running tubeless. If you drive an amphi very often, you already have made peace with potential death, IMHO. Then again, you are probably not going to die from a gas filled manifold, just the tire thing.
 

dougklink

Member
The check valves in an electric fuel pump provide the same anti siphon function. Works great and no solenoid problems.
 

Jon March

Member
Doug-im iconfused/ help me here: Airtex is the biggest mfg of 12v fuel pumps, i was told by the engineer there that elec fuel pumps do allow fuel to flow thru (toward the motor) when they are not running, (altho not at the same force as when running of course)

If they have a checkvalve that stops flow when not running, the car wouldnt run unless the pump was always on.

??
 

dougklink

Member
I believe it depends on the type of fuel pump. A rotary pump like a Carter style won't pass fuel through the rotors when it's not running. A diaphragm style has two check valves, both with small springs on them. The light spring pressure is enough to keep fuel from flowing given that the carb is at about the same level as the gas tank, worst case in a steep hill maybe a foot lower? So not much pressure trying to get the fuel to move to the carb with the pump off.

I tested mine by trying to blow through it, which I could not. It's a small in line pump, and I put it where the magneto valve was, along with a filter. So far no problems in any situation I've encountered. But I'm going to try parking with the nose up a steep grade next chance I have and make sure.

It seems to me like you'd also have to have a leaking needle and seat to let fuel flow too?
 

dougklink

Member
And I'm really confused by, or skeptical of, the scenario described where the float doesn't shut off the fuel because it is on a steep grade? Has anyone taken a car and tried to see at what angle this might occur? And if so is that a realistic angle for the car to attain, even in SF? And it should make a difference in what direction the car is tilted as the hinge side of the float would have to be lowest I believe for this to occur.
 
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