Fuel Leak - Fuel Pump Coupling

[Keith W.]

Just discovered on my newly acquired '70 LT-1 I have a fuel leak at the fuel pump. Its coming from the pump to carb line right at the coupling. Is it best just to replace the whole line? Any suggestions on where to get an OEM part that is correct for this car?

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[Patrick H.]

Re: Fuel Leak - Fuel Pump Coupling

Have you tried to tighten it?
Place a crescent or open end wrench on the square coupling in order to properly support it, then use a flare wrench to tighten.

[Keith W.]

[Patrick H.]

Re: Fuel Leak - Fuel Pump Coupling

flare wrench = line wrench

You may want to find some better than what you can find at Home Depot.
Years ago Doc McCagh recommended Snap-On to avoid rounded fittings. I bought a set of 3 used ones off eBay for far less than retail but more than the local store. They are definitely better than the Craftsman ones I had previously purchased.

[Owen L.]

Re: Fuel Leak - Fuel Pump Coupling

Check something for me first: see the area just above the block where I added the yellow arrow? It appears it could be wet in the seam between the block and the pump housing. If it's wet there then I'd suggest the leak may be between the block and the housing and not the flare fitting, which means a pump replacement or someone who can solder it. If it's not wet it may be solder and nothing to worry about, so try to snug the nut.

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Here's the link to the appropriate HD wrenches above - they have a more enclosed end that surrounds the nut more than a standard c-shaped open end wrench. https://www.homedepot.com/p/Husky-SA...W6PC/203541511 Whatever you buy, make sure it's "Imperial"/SAE/"Standard" (all different labels for inch measures) and not metric. If you are not wanting a set, make sure you get 1/2", 9/16", 5/8" as these are the most common tubing/flare nuts on your car.

[Terry M.]

Re: Fuel Leak - Fuel Pump Coupling

Check something for me first: see the area just above the block where I added the yellow arrow? It appears it could be wet in the seam between the block and the pump housing. If it's wet there then I'd suggest the leak may be between the block and the housing and not the flare fitting, which means a pump replacement or someone who can solder it. If it's not wet it may be solder and nothing to worry about, so try to snug the nut.

Good suggestion Owen about the location of the leak. If it is leaking at the junction of the block and pump housing, I am not sure heat, even for solder, is a good idea. There is a rubber diaphragm and rubber check valves inside the pump, and I think the chance of damaging them if heating them is too great. Additionally any flame around gasoline is not a good idea and I don't think one can get that area of the pump hot enough to flow solder without flame. Also an effective solder joint requires both metal parts to be very clean. The chance of getting those parts clean, even with the pump off the car, is slim. I would suggest something like JB Weld, but it requires cleanliness as well. My guess is you are on a downhill slope. Have a replacement pump at hand.

BTW: I will second Patrick's comment about Snap-on line wrenches. It is a shame they are so expensive, but I too have made my purchases of used wrenches from evilBay. Line wrenches are usually used on equipment that is rusted and in poor shape - at least here in the Midwest. If you live in Southern California or the Southwest desert you can be less picky. Buy the best once and never have to worry about it again. Check Snap-on's on-line catalog for MSRP pricing. Some folks on evilBay are selling Snap-on products for at or near new prices. Also consider that some wrenches have been made thinner more recently, and the older wrenches are more robust in some cases. Shop wisely. Snap-on's motto is: "There IS a difference," and there is. And it is not just in the price. There are date codes on the wrenches. Code charts are on-line, but in some cases the price of older wrenches are driven up by collectors. Yes there are Snap-on collectors who wouldn't think of using their wrenches and keep them "on display." There is a rabbit hole here. Go down it at your own risk. If you are a tool junkie this may not be for you.

If you ever get a chance to attend the Wisconsin NCRS Chapter meet in Kenosha take it. The meet has been held at a Community College conveniently located across the highway from the Snap-on plant. The College and Snap-on have had a relationship since the college opened. You will see Snap-on tools and equipment most of us only dream about. Think about a tool box that greets you as you walk up to it, and records the tool you remove. Oh as you open a drawer a light on the bottom of the next drawer above comes on so you can see the contents of the drawer you opened. Those contents are all arranged in foam cut out for each specific tool. Or wash your hands at a sink built into a Snap-on tool box. Next to a NASCAR Shop tour I once did when we had a meet in Charlotte NC I have never seen so many over the top tools. NASCAR does have the college beat though, just on shear quantity. The college wins on unique items.

[Mark G.]

Re: Fuel Leak - Fuel Pump Coupling

If the fuel is coming from the pipe to pump connection and still leaks after tightening, they sell cone shaped copper sealing washers to go onto the i.f. seats. Used a lot in the hvac industry.

[Mark E.]

Re: Fuel Leak - Fuel Pump Coupling

BTW: I will second Patrick's comment about Snap-on line wrenches.

I like the few Snap-On tools I have, but their set of line wrenches is not one of them. I splurged a couple of years ago and bought a new set from a dealer. Unlike my old Craftsman line wrenches, which fit snugly, the S-Os have a sloppy, loose fit. I should probably share this with the SO tool man but haven't taken the time. But I must say they sure look great.

[Keith W.]

Re: Fuel Leak - Fuel Pump Coupling

Have you tried to tighten it?
Place a crescent or open end wrench on the square coupling in order to properly support it, then use a flare wrench to tighten.

[Sal C.]

Re: Fuel Leak - Fuel Pump Coupling

The sloppy fit (when at rest) is by design. It allows the wrench to grab the fitting on the flats and not on the soft points when pressure is applied. Snap-on led the way with that design decades ago.