70 C20 Fuel System Replacement Advice Needed

[CW4B]

398 (402) V8 mostly stock except for HEI and Carter AFB Competition Series 9506S carb.

My fixer upper sprung a fuel leak at the fuel pump (literally, the fuel pump was spewing fuel out of the fuel pump seam). An inspection of the tubing (steel & hose) revealed some shady work. This isn't a high performance truck (yet), but I'd like to upgrade the fuel system for maximum safety and perhaps include a way to easily measure and adjust fuel pressure. I would prefer to move away from hoses and clamps if possible and also add a fuel filter.

If you've upgraded yours in a similar manner and can recommend a kit or list of parts etc, I will be grateful!

[Mike C]

The GM fuel system works great actually. Put a new fuel pump on it, a new steel line and a Q-jet which has the bronze filter element inside it.

I like the GM stuff, and if you aren't cool with the Q-jet you can get factory steel lines for a big block with a Holley on it. Or you can make your own with steel tube, a bender and a flare kit.

[jocko]

I couldn't agree more, stock is good because it's safe, and it works. Budget-dependent, since you're buying a whole new carb, a nice restored Q-jet would be right at home on your truck. Do you have the stock steel lines all the way to the rubber that led to the old bad pump? Keep in mind there has to be play between the fuel pump and frame-mounted line to allow for the engine rocking when it's making torque. Only a little bit, but that's often accomplished by a rubber line. From the pump to the carb itself, I recommend an all steel factory line. I either use only the bronze or paper filter that Mike mentioned in a Q-jet, or I've sometimes cut my steel line and added a stock-looking (maybe not for our trucks stock) metal filter in lune when the fuel feed line turns to the horizontal back behind the a/c, in that area. They also sell inline (between tank and pump) metal filters, but those would be a custom add-on. New vehicles have them. If you just have a carb and a stock pump, there really isn't any need to add in a pressure regulator - but an inline or at the inlet pressure gauge isn't a bad idea (makes it easier to tell if your pump is bad when it's gone south but isn't spewing gas at the seams - but that's about all it's good for). If I add an inline filter between carb and pump, I like to bend my own lines and use actual fittings rather than just clamped rubber hoses to make the connection - as in the pic below, this was a stock setup on a 65 Impala SS I had, and it's very functional and easy to change, not that I changed it very often..

EDIT: OK, Oops, this pic is missing the one thing I was trying to show... I hadn't added the fuel filter yet. But Just IMAGINE it there in the line... Sorry, I will look for it. Duh.

[CW4B]

OK, I had to take a look at the carb I took off of the engine to understand what you meant by q-jet. I had installed a tiny filter at first (it didn't have one in there), but when it spuddered and spittered my buddy suggested I throw the Carter on there and see if that helped. It did, at least it ran. Perhaps I'll have a go at rebuilding the q-jet in the future?

Unfortunately, the Carter didn't have a filter cavity. So I stitched an inline filter in the hose between the pump and the carb.

The steal tubing looks to be in good condition, but the rubber hoses look too large and made to fit by over tightening the clamps.

Given your explanation, I now realize the importance of rubber to accommodate torque and vibration. I believe I'll replace the pump and hoses but perhaps look into cutting and shaping a steel tube from rubber end of pump connection to carburetor with an inline filter mounted somewhere and a connection for a gauge.

Thanks!

[CW4B]

Originally Posted by jocko

I couldn't agree more, stock is good because it's safe, and it works. Budget-dependent, since you're buying a whole new carb, a nice restored Q-jet would be right at home on your truck. Do you have the stock steel lines all the way to the rubber that led to the old bad pump? Keep in mind there has to be play between the fuel pump and frame-mounted line to allow for the engine rocking when it's making torque. Only a little bit, but that's often accomplished by a rubber line. From the pump to the carb itself, I recommend an all steel factory line. I either use only the bronze or paper filter that Mike mentioned in a Q-jet, or I've sometimes cut my steel line and added a stock-looking (maybe not for our trucks stock) metal filter in lune when the fuel feed line turns to the horizontal back behind the a/c, in that area. They also sell inline (between tank and pump) metal filters, but those would be a custom add-on. New vehicles have them. If you just have a carb and a stock pump, there really isn't any need to add in a pressure regulator - but an inline or at the inlet pressure gauge isn't a bad idea (makes it easier to tell if your pump is bad when it's gone south but isn't spewing gas at the seams - but that's about all it's good for). If I add an inline filter between carb and pump, I like to bend my own lines and use actual fittings rather than just clamped rubber hoses to make the connection - as in the pic below, this was a stock setup on a 65 Impala SS I had, and it's very functional and easy to change, not that I changed it very often..

EDIT: OK, Oops, this pic is missing the one thing I was trying to show... I hadn't added the fuel filter yet. But Just IMAGINE it there in the line... Sorry, I will look for it. Duh.

If you happen to click another pic with the filter, please share. And thanks so much for your feedback.

[jocko]

Here ya go - I grabbed the wrong 65, it was this one - anyway, this is what I'm talking about. A little more difficult to stick it there if your truck has a/c, might need to move it back a bit. If you know you're gonna go with a Rochester Q-jet in the near future, you are good with just the inlet filter at the carb that Mike mentioned, but this is another way to skin the cat.

[CW4B]

Originally Posted by jocko

Here ya go - I grabbed the wrong 65, it was this one - anyway, this is what I'm talking about. A little more difficult to stick it there if your truck has a/c, might need to move it back a bit. If you know you're gonna go with a Rochester Q-jet in the near future, you are good with just the inlet filter at the carb that Mike mentioned, but this is another way to skin the cat.

Is your filter mounted or suspended inline with the steel tubing?

[jocko]

suspended, no bracket necessary

[RichardJ]

If the body of the pump broke somehow, be sure and check the engine oil. See if the oil level went up or if the oil smells like gasoline.

I don't understand why so many people have such a problem placing an inline filter before the pump. The rubber line is already there. Just add a little extra line and a little more of a loop.

I recently had a pump fail. I cut the fuel filter open and found the inlet side of the filter half clogged with junk. I pulled the sending unit out of the behind the seat tank. The screen or sock was half missing. The remaining part of the screen would simply disintegrate and fall to the ground when toughed. That was the same material in the filter.
I cut open the pump and it was as clean as a whistle. The suction-side valve sealed OK, but the outlet-side valve passed air in both directions. The stone filter in the carb was clean as well.

Why would anyone want to allow crud from the tank to pass through the pump?

[jocko]

These are the frame types - new cars use them also. I have a canister one, a GM type, that will be used on my K20 when I get around to it (Part # GF-62). Like I mentioned above, I prefer the type with fittings over the clamped type. The rubber clamped over the filter isn't the issue, it's the rubber clamped over the chopped fuel line - there is no expansion/nipple to retain the rubber line. Normally works just fine though. Good point on the pre-pump filter. GM didn't do it for a long time - and as old as our tanks are, screen in place or not, it's cheap insurance.

[davepl]

The single most important skill I think I've learned in my restoration projects is the ability to plan, bend, cut, and flare tubing. I use stainless steel tubing which is hard as heck, but if you start out with mild steel it's not bad to work with.

It's a bit of an investment. The hydraulic Mastercool (and other names) flaring tool is about $300 I think. Then you need fittings and practice.

I just did a fuel system last night. There is NO rubber. It's still line to braided teflon to steel lines. Here's a pic of the throttle body... not perfect, but still fairly tidy.

When you're done, however, it looks nice and your risk of fire or fuel spill should be greatly redudced. I'm pretty paranoid about gasoline so don't like rubber hoses, hose clamps, plastic filters, that sort of stuff.

[davepl]

Originally Posted by RichardJ

Why would anyone want to allow crud from the tank to pass through the pump?

You don't, but isn't there a pickup sock on the pump anyway?

The last system I built I used a 100-micron -12AN filter before the pump and a 10-micron -10AN filter after the pump. I figure that's close to ideal, but probably overkill.

I always wondered if that meant the pump would eventually fill up with particles greater than 10 microns but less than 100!

[Mike C]

Originally Posted by davepl

The single most important skill I think I've learned in my restoration projects is the ability to plan, bend, cut, and flare tubing. I use stainless steel tubing which is hard as heck, but if you start out with mild steel it's not bad to work with.

It's a bit of an investment. The hydraulic Mastercool (and other names) flaring tool is about $300 I think. Then you need fittings and practice.

I just did a fuel system last night. There is NO rubber. It's still line to braided teflon to steel lines. Here's a pic of the throttle body... not perfect, but still fairly tidy.

When you're done, however, it looks nice and your risk of fire or fuel spill should be greatly redudced. I'm pretty paranoid about gasoline so don't like rubber hoses, hose clamps, plastic filters, that sort of stuff.

I have that Mastercool kit as well. If you ever struggled with double flares for brakes you can really appreciate how good a tool this is!

I save all old lines anymore to be able to pirate the fittings from and build new ones. I usually just use the OEM type line material since it lasts 50+ years in my part of the world.

[CW4B]

Originally Posted by davepl

The single most important skill I think I've learned in my restoration projects is the ability to plan, bend, cut, and flare tubing. I use stainless steel tubing which is hard as heck, but if you start out with mild steel it's not bad to work with.

It's a bit of an investment. The hydraulic Mastercool (and other names) flaring tool is about $300 I think. Then you need fittings and practice.

I just did a fuel system last night. There is NO rubber. It's still line to braided teflon to steel lines. Here's a pic of the throttle body... not perfect, but still fairly tidy.

When you're done, however, it looks nice and your risk of fire or fuel spill should be greatly redudced. I'm pretty paranoid about gasoline so don't like rubber hoses, hose clamps, plastic filters, that sort of stuff.

Wow, that looks great. I believe I'm going to acquire that skill before I do my full rebuild.

[davepl]

Thanks! Really the worst case for bending and flaring (typical automotive, anyway) is 3/8" stainless. It's really tough and strong.

Turns out double flares do work just fine. You can apparently get away with single flares for AN stuff but I did all double.

I had a couple of leaks when I first fired it up but they turned out to be fittings that were only finger tight (whoops, my mistake!). I was actually impressed how little they leaked for being loose! And none of the PTFE hose ends had any problem, they all sealed great.