Leaking Fuel Pump Diaphragm?

[BRL]

My fuel tank is still located in the cab behind the seat and I know that if I disconnect the inlet line from the mechanical block mounted fuel pump the fuel will drain the tank dry without hesitation.
My question is that if the mechanical fuel pump diaphragm were to rupture or crack sometime due to age or something would it be possible for raw fuel to find its way into the crankcase?

[Steeveedee]

Yup. Fuel can flow until the level in the engine is the same as the level in the tank.

[BRL]

Originally Posted by Steeveedee

Yup...

That is scary!

I might drive my truck every few days now that I'm retired and it's embarrassing to have to crank the engine over for 20-30 seconds every time before it finally starts using today's fuel.

So I've decided to eliminate that problem by deleting the mechanical pump and replacing it with an electric.
Yea this pump is probably overkill but those selinoid pumps sound like a friggin' jackhammer.

Thank you for the reply and Happy New Year!

[Steeveedee]

You're welcome! I have an electric fuel pump that my FiL put on. He did it because he would run a saddle tank dry and the switch tanks. The electric pump got fuel to the engine sooner. It is a solenoid type, and yes, it's a real clacker. I do use it if the truck hasn't been started for a few days.

[72c20customcamper]

Going to electric I would put an oil sender safety cutout on it or an inertia switch .

[BRL]

I totally agree with you on that suggestion (thank you )although an oil pressure switch would probably put me back in the same hard start boat I'm already in.

If I get hit hard enough to rupture a fuel line or even the in-cab tank itself, the fuel isn't going to need any help spilling everywhere.

There's something to say about peace of mind though.

Standard Motor Products FV-7 Fuel Pump Cut-Off Switch Assorted, One Size https://a.co/d/7eUrqhi

[68 TT]

Originally Posted by BRL

That is scary!

I might drive my truck every few days now that I'm retired and it's embarrassing to have to crank the engine over for 20-30 seconds every time before it finally starts using today's fuel.

So I've decided to eliminate that problem by deleting the mechanical pump and replacing it with an electric.
Yea this pump is probably overkill but those selinoid pumps sound like a friggin' jackhammer.

Thank you for the reply and Happy New Year!

I ran that Carter electric pump for years on my Chevelle. It works great and is pretty quiet. I made it quieter by mounting it on top of and through a set of rubber shock mount bushings so there was no metal to metal contact on the bracket to the frame or the mount bolts to the bracket.

[68 TT]

My cousin had a fuel pump diaphragm leak into his engine while it was running and fill up his crank case. It worked just enough that the engine still ran but still leaked fuel into the engine. It diluted the oil down so much that it trashed the bearings in no time flat. We ended up having to put a different crank and cam into it because the journals and lobes were so torn up. This happened in one days commute to work on the highway about 30 miles round trip.

[BRL]

Originally Posted by 68 TT

My cousin had a fuel pump diaphragm leak into his engine while it was running and fill up his crank case...

That is sad, other than a leaking diaphragm causing a car fire I can't think of a worse case scenario.

[BRL]

Originally Posted by 68 TT

I ran that Carter electric pump for years on my Chevelle. It works great and is pretty quiet...

I fired up the engine for the first time a little while ago with the new pump and it was so quiet I had to physically get under the truck and touch it to make sure it was still working.
It was but I quickly discovered that I need to fabricate a tin heat shield because of the close proximity of the exhaust pipe.
Other than that it ran great and fired right up after sitting for so long.

[geezer#99]

Hope your hearing is bad and you won’t hear that constant loud buzz from the pump.
You can reduce it by using some 1/2 inch thick rubber between the bracket and the frame.

[BRL]

I'll never hear it.

[Steeveedee]

BOOM BOOM BOOM whirrr

[BRL]

Originally Posted by Steeveedee

BOOM BOOM BOOM whirrr

IT SHALL BE GLORIOUS!

[BRL]

...ok so what the heck is this supposed to shrink around?

[BRL]

Originally Posted by geezer#99

Hope your hearing is bad and you won’t hear that constant loud buzz from the pump.
You can reduce it by using some 1/2 inch thick rubber between the bracket and the frame.

Finally hooked the pump up and was able to hear it running for the first time.
Really not that bad if you consider the fact that some people pay good money for a noisy Pete Jackson gear drive.
Much more leak testing and cleanup before I take a test drive to determine if I need a regulator or not but I think I'm going to be happy with it in the end.

[geezer#99]

You’ll still hear it!
And the kicker is it won’t change your starting problem.

[BRL]

You have no idea how loud I crank my stereo and it will refill my float bowls before I turn the key so yes it will fix the fuel evaporation issue and start the engine right up.
And I'll stop worrying about a crankcase full of gasoline when the mechanical fuel pump diaphragm finally fails.
You sound like a geezer.

[geezer#99]

So what’s the pressure output on that pump?

[BRL]

Good question, I think it's low enough to not require a regulator but...
Carter Electric Fuel Pump https://a.co/d/3nUCTlr
It's supposed to be quiet but if not I'll just tell everybody it's feeding duel 4 barrels and leave the hood down.

[IT Cowboy]

Can someone explain the electric fuel pumps to me like I am a 3rd grader. Are they connected to a relay and the ignition so that is how they come on and what keeps it from just flooding the carb if you turn just the ignition or a pumps switch on.

[BRL]

Originally Posted by IT Cowboy

Can someone explain the electric fuel pumps to me like I am a 3rd grader...

I went to YouTube videos for inspiration, of course the pump isn't working yet and I'll toss in a fuel pressure regulator if necessary.

Wiring that stuff up under the dash was another adventure.

Love it LockDoc, I'll look into the heavy duty version.

My Sister got me one of those flashlights that clip to the bill of a baseball cap and I don't know how I ever lived without one.
The bill kept bumping into everything though so I broke out the scissors.

[dmjlambert]

Originally Posted by IT Cowboy

Can someone explain the electric fuel pumps to me like I am a 3rd grader. Are they connected to a relay and the ignition so that is how they come on and what keeps it from just flooding the carb if you turn just the ignition or a pumps switch on.

The carb does not get flooded with an electric fuel pump or mechanical fuel pump because the carburetor has a float in a bowl connected to a needle and seat valve that shuts off the incoming supply of fuel. Pretty much just like a toilet tank shuts off incoming water when the tank is full. If that piece is working correctly, the carburetor only lets in enough gas to fill the internal bowl. The needle and seat and sometimes the float are some of the items typically replaced during a carburetor rebuild.

[IT Cowboy]

Originally Posted by dmjlambert

The carb does not get flooded with an electric fuel pump or mechanical fuel pump because the carburetor has a float in a bowl connected to a needle and seat valve that shuts off the incoming supply of fuel. Pretty much just like a toilet tank shuts off incoming water when the tank is full. If that piece is working correctly, the carburetor only lets in enough gas to fill the internal bowl. The needle and seat and sometimes the float are some of the items typically replaced during a carburetor rebuild.

OK durr, like a gravity fed motorcycle tank and carb

[BRL]

Originally Posted by IT Cowboy

OK durr, like a gravity fed motorcycle tank and carb

Sorry about that IT Cowboy, I'm in no position to explain that stuff to anybody.