How to troubleshoot Holley 2300 fuel bowl side leak - FINAL

62Ranchero200

62Ranchero200

Famous Member
Greetings Ford Six Fans,

This is in a '62 Falcon Ranchero.

I have replaced my mechanical fuel pump, and now on to the NEXT problem - fuel dripping from the underside of the carb on the fuel bowl side. :roll:

It's a Holley 2300 (Part # 4412-S), mounted with the throttle shaft parallel to the crank/camshaft, but mounted with the fuel bowl to the outside.

Mounted on the engine, the fuel bowl sits quite close to the shock tower, in fact so close that I can't pull the rear lower fuel bowl bolt all the way out without hitting the shock tower.

Between the intake manifold, headers, shock tower, lines and wires, it's almost impossible to tell where the fuel drip is coming from with the carb mounted on the engine, even from underneath the car or with a mirror.

I pulled the carb off the engine, and it's sitting on a short piece of 2" X 8", with the throttle lever off one side of the 2 X 8 so that the carb sits flat, the fuel bowl side of the carb hanging off of the 2 X 8 so that I can look for leaks, and the entire 2 X 8 right at the edge of my workbench so that any gas that drips out falls all the way to the floor.

My issue is, with the carb off of the engine, how do I get gas into the bowl? So far, I've thought of the following:

* Buy an electric fuel pump to continuously pressurize the fuel bowl using the inlet fitting - this would probably be the best way, but I don't have a small tank or gas can with an opening in the bottom to connect to an electric fuel pump
* Use a turkey baster to squirt gas into the site plug hole (this is about a 1/4" hole)
* Use a flexible straw to put gas into the vent (3/16") or site plug hole (put the straw down into a tall, narrow bottle full of gas, put my finger over the top of the straw, pull the straw out of the gas, put it over the carb vent or site plug hole, then take my finger away from the straw)

If I can't figure out exactly what is leaking, I may buy another bowl ($50 at Summit Racing).

Thanks
Bob
 
Well, you may need to have to apply pressure to get it to leak. But first, I would get a fuel tank off a small engine like a mower or snow blower (Hmm probably don't have one in the deep south) and some fuel line. Connect 'er up and hang the tank up high to give the fuel some head pressure. You might just find it that way.
 
Bob, leakage can occur at the lower bowl bolt sealing washers.
Also at the metering block to bowl gasket. Remember Quick Fuel Tech. uses a different contour at the lower part of the gasket. You can trim a Holley gasket, but i would not recommend it. You can use a Holley gasket between the metering block & the carb body.
Leakage can also occur at the inlet fitting to bowl & or at the fuel line fitting to the inlet fitting.
Remove the bowl & place a straight edge on the lower part of the bowl to make sure the bowl is not warped. Bill
 
62Ranchero200":1qv9pg9n said:
Greetings Ford Six Fans,

This is in a '62 Falcon Ranchero.

I have replaced my mechanical fuel pump, and now on to the NEXT problem - fuel dripping from the underside of the carb on the fuel bowl side. :roll:

It's a Holley 2300 (Part # 4412-S), mounted with the throttle shaft parallel to the crank/camshaft, but mounted with the fuel bowl to the outside.

Mounted on the engine, the fuel bowl sits quite close to the shock tower, in fact so close that I can't pull the rear lower fuel bowl bolt all the way out without hitting the shock tower.

Between the intake manifold, headers, shock tower, lines and wires, it's almost impossible to tell where the fuel drip is coming from with the carb mounted on the engine, even from underneath the car or with a mirror.

I pulled the carb off the engine, and it's sitting on a short piece of 2" X 8", with the throttle lever off one side of the 2 X 8 so that the carb sits flat, the fuel bowl side of the carb hanging off of the 2 X 8 so that I can look for leaks, and the entire 2 X 8 right at the edge of my workbench so that any gas that drips out falls all the way to the floor.

My issue is, with the carb off of the engine, how do I get gas into the bowl? So far, I've thought of the following:

* Buy an electric fuel pump to continuously pressurize the fuel bowl using the inlet fitting - this would probably be the best way, but I don't have a small tank or gas can with an opening in the bottom to connect to an electric fuel pump
* Use a turkey baster to squirt gas into the site plug hole (this is about a 1/4" hole)
* Use a flexible straw to put gas into the vent (3/16") or site plug hole (put the straw down into a tall, narrow bottle full of gas, put my finger over the top of the straw, pull the straw out of the gas, put it over the carb vent or site plug hole, then take my finger away from the straw)

If I can't figure out exactly what is leaking, I may buy another bowl ($50 at Summit Racing).

Thanks
Bob
Click to expand...

There should be no need to pressurize the fuel bowl to find the leak just use the vent tube to fill the bowl. There are only a few places or parts that can cause the fuel bowl to leak.

1. Bowl gasket and or a warped fuel bowl or carb body surface that the metering block mounts against. You can use a straight edge to check that these are still straight.
2. Bowl screw gaskets check that they are not missing or deteriorated.
3. The Accelerator pump diaphragm.
4. Metering Block gasket.
5. Fuel inlet fitting depending on type.

If the carb sat a while the gaskets might of dried up and a new carb kit may be all it takes. While you have the fuel bowl off also check that the power valve and it's gasket are in good condition too. Good luck :nod:
 
Bubba, thanks i forgot to mention the accelerator pump diaphragm.
Because of the ethanol blended fuels, i have been using the green pump diaphragms.
Holley also thought it was a good idea. 50cc part# 135-9, 30cc # 135-10.
I have been using them since our dictators in Washington wanted to blend fuel with ethanol.
When doing A/F tests with non ethanol fuels the 14.75 cruise & the 12.8-13.1 still apply.
With ethanol you need to richen up because you need a lower A/F number so you don't fry the pistons.
A fuel injected engine with o2 sensors compensates for this automatically.
 
:beer: good info Bill I guess we were both typing our answers about the same time. Yep I am not a big fan of the Ethanol fuel blends seams to cause more trouble then it's worth let along the cause of some extra burden on the Food supply and Costs in parts replacements. Now if they could actually make the Ethanol at a lower cost then it sells for and without all the Taxpayer Subsidies then it might be worthwhile! :rolflmao: take care :nod:
 
not 2 jack-a-thread but
don't it burn cleaner & produce more HP?
I just wish they wouldn't use the food product route 2 produce it, tho
 
I think I may know what is causing the fuel leak ...

When the fuel leak first occurred, I tried replacing the accelerator pump diaphragm. These come in 30cc and 50cc sizes, and, unable to quickly find which size accelerator pump came with my Holley 2300 / 4412-S 2-BBL carb, I guessed that, since it's a smaller carb, it must have come with the 30cc accelerator pump.

I just found the information on Holley's web site and it came with the 50cc accelerator pump.

So, I have the spring and housing for the 50cc accelerator pump, but currently have the diaphragm for the 30cc accelerator pump.

Could this cause a fuel leak at the accelerator pump?

Thank you,
Bob
 
Darn good chance. Bob get the part # for the 50cc pump & order it now. A leak there is a big fire hazard. Bill
Chad, ethanol blend % varies from 3 to 10%.
A dyno test considering the blend might prove benificial.
 
@vssman,

Your tip about using a small gas tank to pressurize the carb with just gravity was a good one - thank you. I found a 3 gallon motor boat gas tank at Academy, filled it partially and connected it to the carb's inlet (see below).



I did replace the accelerator pump diaphram, which probably would have leaked eventually ... but it turned out that the source of the current leak was the rear lower bowl bolt (closest to the fuel line inlet, just cut off in the photo). Have been worried about these bolts ever since I began using the Quick Fuel metering block; the metering block is about 1/16" thicker than the Holley block. That may not sound like much, but even with the Holley block the bolts only thread about 1/4" into aluminum, and with the Quick Fuel block they can only thread about 3/16" into aluminum. I've had the metering block off many dozens of times in the process of tuning the carb, and I'm afraid that the aluminum threads in the carb body may be the worse for wear. There was a fuel drip from the rear lower bolt before; I tightened it as much as I dared without stripping it, and now fuel still seeps out slowly. However, I can live with that until I replace the carb with the new 600 CFM, vacuum-secondary, electric-choke, tumble-polished Holley carb I picked up at my local speed shop yesterday.

Started the Ranchero and it started and ran great! But I'll post about that in my DS2 ignition thread, as it's really the conclusion of that thread.

Thanks
Bob
 
Glad to hear you found the problem. I recently went through a similar issue with an old 88 Polaris quad carb and used the same trick to find a leak.
 
Bob, Holley markets a heli-coil kit for stripped out threads in the main body.
 
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