Leaking Fuel Pump Diaphragm?
 

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?

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

That is scary! :eek:

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. :mad:

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. :rolleyes:

Thank you for the reply and Happy New Year! :three:

Re: Leaking Fuel Pump Diaphragm?
 

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.

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

Had to bend the fuel pump bracket so that I could wrap it over the frame but I think it will be fine.
Trying to fabricate everything together before I do the actual swap so that I can still drive the truck in the meantime.
More parts arriving tomorrow like pre-pump filter, electrical etc.
The pump is probably within a foot of the gas tank as recommended but truthfully the tank will feed fuel all the way to the mechanical pump up front anyway so there shouldn't be any problem.
Will probably put in a little tin shield between the exhaust and the pump just to keep it cooler.
ETA: You might be wondering why I didn't just stick the pump inside the frame.
I think it would be too tall and there is 56 year old metal brake line tubing in there I didn't want to risk damaging...it'll work. :D

Re: Leaking Fuel Pump Diaphragm?
 

I think the pump bracket installation will prove to be the most difficult part of this whole project.
I'm 67 years old and I fell on Christmas eve and injured my ribs so two weeks later it still hurts to crawl around under the truck.
Turns out walking while intoxicated is almost as stupid as driving while intoxicated.
Anyway there was already a hole in the upper frame and also some extra clearance in the cab for the seat perch which makes it easier to install and remove the pump in the future.
Oh, and I got the inertia switch yesterday.
I'm in no real hurry to finish this job as the truck is still drivable with the mechanical pump working.

Re: Leaking Fuel Pump Diaphragm?
 

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.

Re: Leaking Fuel Pump Diaphragm?
 

I'll never hear it. :cool:

Re: Leaking Fuel Pump Diaphragm?
 

:lol: BOOM BOOM BOOM whirrr

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

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. :rolleyes:

Re: Leaking Fuel Pump Diaphragm?
 

So what’s the pressure output on that pump?

Re: Leaking Fuel Pump Diaphragm?
 

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. :lol:

Re: Leaking Fuel Pump Diaphragm?
 

IT SHALL BE GLORIOUS! :metal:

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

Time to figure out how I'm going to route the electrical wiring for this pump, and we all how good I am with that stuff. :lol:

Re: Leaking Fuel Pump Diaphragm?
 

OK I now have everything I need to complete the job, except a garage heater.
I'll find this thread and keep you updated...next spring. :rolleyes:

Re: Leaking Fuel Pump Diaphragm?
 

I've used one of these for years.

https://www.revolutionelectronics.co...Fuel_Pump.html

Re: Leaking Fuel Pump Diaphragm?
 

Thanks for the idea. :)

Years ago I switched to electronic Ignition and ran 12V directly from the battery to a separate on/off switch, it has worked well for years and now I'm thinking just route the Ignition plus the pump through a relay so I can throw the switch, wait a few seconds for the pump to fill the carburetor bowl and then turn the key.

Re: Leaking Fuel Pump Diaphragm?
 

I just wanted you people to know how impressed I am with myself for my fuel pump wire routing from under the dash to inside the frame.
Yea that's about as far as I got so far but that took some serious planning and sweating on my part and the garage is freezing.
I put a piece of vacuum line through a preexisting hole in the frame and secured it with tiny zip ties both top and bottom and fed the pump wire through that to prevent any chafing and the wire is a safe distance from any headder heat.
Believe me when I tell you I'm getting older and I'm out of shape so it takes more effort to accomplish this stuff.
And It's getting harder to reach around and pat myself on the back but I'll definitely manage that. :cool:

Re: Leaking Fuel Pump Diaphragm?
 

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.

Re: Leaking Fuel Pump Diaphragm?
 

Good Job!

This might help.....
.

Re: Leaking Fuel Pump Diaphragm?
 

:lol: Indeed, good job!

Re: Leaking Fuel Pump Diaphragm?
 

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. :haha:

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. :lol:

Re: Leaking Fuel Pump Diaphragm?
 

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.

Re: Leaking Fuel Pump Diaphragm?
 

OK durr, like a gravity fed motorcycle tank and carb

Re: Leaking Fuel Pump Diaphragm?
 

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

Re: Leaking Fuel Pump Diaphragm?
 

It's entirely possible for the scenario you asked about to happen. The fuel just doesn't come through the carburetor- and is actually a worse situation. It is unbelievably rare, but I've seen it...and in the case of a bad needle and seat or float, much less of a problem, unless someone just leaves the engine running. I've seen crankcase oil dilution from that, too.

Re: Leaking Fuel Pump Diaphragm?
 

That's exactly what I was looking at.

Years ago I had a really nice '69 Nova with the deluxe trim and the wrong year rally wheels. :lol:
One day I noticed fuel dripping out of a bad mechanical fuel pump through a weep hole in the pump and of course replaced it.
That tank is located way in the back under the trunk and under the frame and who knows if any fuel flowed into the crankcase before I caught it, didn't know enough to check the dipstick level.
Now picture a 20 gallon gas tank essentially turned sideways behind you up in the cab, well above the frame and a leaking fuel pump with open access to your engine crankcase and your garage floor.

Re: Leaking Fuel Pump Diaphragm?
 

Getting ready to try to figure out the fuel line routing to my electric pump.
Thought it might be too close to the transmission crossmember but a short piece of rubber fuel hose will slide right over the top of the crossmember to meet a hard line.
...so far so good. :)
Pinched the short rubber fuel line from the tank to the beginning of the hard line with vicegrips and cut the line.
Fuel started pouring all over me and the floor?!?
Thought it was just residual fuel in the line from the mechanical pump up front so I allowed it to drain out...but it continued. :confused:
Turns out I cut the fuel line on the wrong side of the vicegrips and the tank was draining out all over me.
Decided right there and then that I don't want a woodstove in the garage for heat and I'm done tinkering for tonight. :o

Re: Leaking Fuel Pump Diaphragm?
 

I put a carter fuel pump on my big block with quadrajet and the pressure was too much and caused it to flood out. Put a 3# pressure rgulator on it and it works fine.

Re: Leaking Fuel Pump Diaphragm?
 

Good to know thanks.
The Carter P4070 is supposedly putting out between 4-8 psi and will be feeding a Edelbrock 600 cfm model 1405 (I think) so it might or might not need a regulator in the end.
Should be interesting if I get my lazy tail up to the garage and continue installing the dang pump. :rolleyes:

Re: Leaking Fuel Pump Diaphragm?
 

My 72 has a mechanical pump with a return line. If I put a pressure regulator on the feed line to the carb will the pump handle the "back pressure" or do I need to plumb in a return T from the carb supply line to the pump return line and put a check valve in there too. I think my return is 3/8

Re: Leaking Fuel Pump Diaphragm?
 

Went to remove the hard line that goes from the tank to the mechanical fuel pump that runs along inside the frame, and all went well except for that last clip which of course is hidden in the most inaccessible place on the truck.

There probably is a simple technique for removing that clip but I don't know what it is.

Spent about 2 hours fighting with that stupid thing with every feasible tool I could come up with in my toolbox until finally it broke free from the frame.

I'm taking the rest of the evening off. :waah:

Re: Leaking Fuel Pump Diaphragm?
 

-
Not only is it hard to get to but you can't see in there either.... :(

Re: Leaking Fuel Pump Diaphragm?
 

I figured if you replied at all it would go something like: "You big dummy, all you gotta do is...:rolleyes:

I appreciate the sympathy and understanding, that thing was a nightmare! :whine:

Re: Leaking Fuel Pump Diaphragm?
 

Ok, I really am in the market for one of these babies! :D

Re: Leaking Fuel Pump Diaphragm?
 

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. :lol:
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. :cool: