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73 K2500 Barn Find Revival on the Cheap :

yellowK20

yellowK20

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I feel like this is a dumb question, but I have not run into this problem before .

My 73 K2500 is putting tons of fuel into the crank case In a very short time . Originally I thought it was the stupid Holley so I rebuilt it with new floats . But the problem persisted . I’m guessing the only other way it could be happening is from the mechanical pump?

657D8804-670A-4541-AE77-9A7B92A3BA0C.jpeg
 
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yellowK20 said:
I feel like this is a dumb question, but I have not run into this problem before .

My 73 K2500 is putting tons of fuel into the crank case I man very short time . Originally I thought it was the stupid Holley sonInrebuilt it with new floats . But the problem persisted . I’m guessing the only other way it could be happening is from the mechanical pump?

View attachment 310669
Click to expand...
That's usually the first suspect.
The only other thing I had that did this was a few very low compression cylinders, like 40-60 psi.
Unburned fuel was getting past the rings
 
I've seen engines that were run in cold climates with a faulty thermostat (or none !) run cool enough to cause oil dilution,especially if its not driven long or far enough to fully open the choke on a carbed engine..

But a ruptured diaphragm on a machanical fuel pump can & will pump raw fuel into the crankcase,though on a SBC the cavity where the fuel pump push rod is I think doesn't have a large "drain hole",usually you'll see it pumping out of the weep hole on the pump casting once it starts leaking at the diaphragm..

I've also seen older Holley carbs that can work perfect ,then decide to become a flushing toilet while driving intermittently too..
 
That’s why I automatically went to the carb I have had that happen before . I have also had fuel pumps leak but never internally . It totally makes sense now that I sit and think about it . But like I said I have never ran in to it before LOL
 
Long story short this was a “rescue” from behind a barn at an old farm here that the heirs have decided to subdivide. It has been sitting for at least 25 years according to the guy that sold it to me ( the oldest son )

All 4 brakes have rusted up the calipers are shot and of course the fuel tanks are full of varnish.
 
And the fuel pump diaphragm probably looked like a 50 year old dry rotted inner tube and ruptured right away..:eek:

New fuel pumps are cheap for a SBC..under $20 at most parts stores,I'd replace it even if it seemed OK..
There is a bolt you can remove and put in a longer one to hold the push rod in place on the front of the block too,makes it much easier..
Just remember to remove the longer bolt and put the original one back in..(and don't tighten the long bolt much,it only needs to be snug enough to hold the push rod)..

Fuel pump on the 1973 307 I put in my van is still the original !..but I wouldn't trust it out of my driveway if I put it back on the road after sitting since 2003--I have started & run it every few months but that means squat..I bet it still has original steel shim head gaskets too,that is scary,they are 45 years old!..

I ran the gas tank dry,and use a old lawnmower gas tank to the fuel pump to run it,and move it around the yard..last time I moved it the front brakes were almost seized up...

I bet the gas tank will be junk if I go to drive it ever again despite looking nice externally..bet the top where the sending unit goes is rotted,and what fuel remained in it is probably shellac too..
 
I dropped the tanks and rinsed them out with out steam cleaner , all the rubber lines are new , and it’s getting a new pump today lol
 
Still waiting for New sending units for the tanks , I gave up on the Holley and put a Jet Stage 2 Q-jet on this thing and it runs like a sewing machine now !

I roadkilled a fuel can so I could move it around the yard . I got the rear brakes cleaned up and working good but the front calipers are toast . So that’s on the wish list

Next on the agenda is new plugs , And to figure out the vacuum ports for the distributior and PCV valve

E5644DA1-D47C-451E-9FE2-F56ECC61D931.jpeg
 
Edited the title , will use this thread as kinda build thread ...... well more of cheap entertainment kinda “build”

Zero budget ( for now) , parts will be either what I have laying around , can trade for , or what I can sell from my stash to buy new stuff.
 
yellowK20 said:
I dropped the tanks and rinsed them out with out steam cleaner , all the rubber lines are new , and it’s getting a new pump today lol
Click to expand...

Could you elaborate on the steam cleaning process? Will this eliminate all fuel/fuel vapors to the point where you can weld on the tank with no danger?
 
Can we all further discuss fuel pumps? i suspect today's autostore pumps may NOT be correct in terms of pressure.

Are there adjustable fuel pumps----like being able to change springs to be able to change pressure?
 
vandelay industries said:
Could you elaborate on the steam cleaning process? Will this eliminate all fuel/fuel vapors to the point where you can weld on the tank with no danger?
Click to expand...


It's probably safe to weld on after cleaning, you could always back purge the tank with nitrogen to prevent a flare up if you were worried about it.

Honestly, as thin as these tanks are and how cheap aftermarket replacements are I wouldn’t bother lol
 
vandelay industries said:
Can we all further discuss fuel pumps? i suspect today's autostore pumps may NOT be correct in terms of pressure.

Are there adjustable fuel pumps----like being able to change springs to be able to change pressure?
Click to expand...


I just got a new AC Delco (Delphi now) and it’s perfect about 6-7 psi
 
I put a new Ac Delco 40 gph on my 350 qjet, in December, had fuel delivery issues at highway speeds under light medium loads.
Once I installed an electric 38 gph Edlebrock it runs great.
I did purchase a high performance
80 gph mechanical pump from Jegs, but I didn't use it.
20 years + ago I remember buying big block fuel pump for sbc, I couldn't find anything listed like when I purchased the 80 gph pump
 
yellowK20 said:
Edited the title , will use this thread as kinda build thread ...... well more of cheap entertainment kinda “build”

Zero budget ( for now) , parts will be either what I have laying around , can trade for , or what I can sell from my stash to buy new stuff.
Click to expand...

My kind of build! I like it!
 
Wes Harden said:
I put a new Ac Delco 40 gph on my 350 qjet, in December, had fuel delivery issues at highway speeds under light medium loads.
Once I installed an electric 38 gph Edlebrock it runs great.
I did purchase a high performance
80 gph mechanical pump from Jegs, but I didn't use it.
20 years + ago I remember buying big block fuel pump for sbc, I couldn't find anything listed like when I purchased the 80 gph pump
Click to expand...


This thing is pretty much stock except for the Perfomer Intake , it even has the stock aircleaner still not sure why they bothered with the intake and the crappy Holley .

If I do anything to this thing engine wise it will be a 5.3 or a 6.0 swap and I reallllly doubt that will happen .

I have a very bad case of Automotive A.D.D.
 
yellowK20 said:
It's probably safe to weld on after cleaning, you could always back purge the tank with nitrogen to prevent a flare up if you were worried about it.

Honestly, as thin as these tanks are and how cheap aftermarket replacements are I wouldn’t bother lol
Click to expand...
Exactly I wouldn't bother.
I can see an old car that no one makes tanks for but squares, no question just buy new.
Hell, my friend had his fuel pump go on the 98 Chevy truck and he just bought the tank with fuel pump installed from rock auto, and he's in California, no rust or anything, just easier and safer
 
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