Fuel sytem rebuild...

[PancakeMix]

I replaced my mechanical fuel pump a couple years ago. Truck started having problems. I'm 90% sure the fuel pump died again. This time I'm up for a bigger project and some upgrades.

I'm going to replace my dual tanks and mechanical fuel pump with a single replacement poly tank and electric fuel pump. I just want to simplify everything.

The problem I'm having is figuring out what to put back in. I'm slowly finding out that the previous owner didn't do a very good job putting things back together.

Example: when I went to replace the fuel pump last time, I says, "gimme an '85 chevy fuel pump." Well, long story short, I had an older fuel pump without the return line. I'm not even sure the dual tanks work -- or were installed properly. Just a big headache...

So I want to make sure I'm going about this right -- I just want a single saddle tank mounted on the PASSENGER side. (don't want to have to make a million bends when I make the new fuel line). I think I need GM Part #6429439 -- but this says it's for drivers side only -- is that because it's assuming I have dual tanks? Or do I need a different sending unit?

Then I run a rubber line off the sending unit into a filter on the frame rail.

Then I run another rubber line from the filter to the electric pump (keeping it all as close to the tank as possible).

Then one last rubber line from electric pump to some brand new nicopp line.

Nicopp line run as close to the carb (edelbrock 1406) as I can get. Might have to re use the old fuel line that runs up behind the water pump and some more rubber line.

Should I add one last filter before I go into the carb?

Do I need a return line?

[hatzie]

The single tank in 1985 was mounted on the LH side. Tell em you have dual tanks and you need the RH sender.
When most folks change things they introduce additional new failure points.
The Mechanical fuel pump is easy to deal with and they are usually very reliable. This is why GM used them into the mid 1990's on the diesels. Electric pumps don't self-prime very well and are sensitive to location and in my experience most aftermarket electric pumps are not as reliable as a good Delco mechanical pump.
Every connection in the fuel lines from soft to hard line/fittings is a potential leak point. The first rule of fuel system feed and return line design is to... Minimize the number of connections for reliability and don't cheap out on clamps or the fuel hose itself. Electric fuel pumps introduce another connection point and take away the end mount for the carburetor to fuel pump hardline.

The stock Rochester Quadrajet usually has a 10 micron or so sintered bronze or paper filter in the inlet fitting. I wouldn't go less than that and I don't recommend mounting the filter down where road debris can bash it off the frame without a heavy trash shield... I spread an unprotected Racor filter unit along the road after clobbering a peeled big truck tread with the bottom of my truck.

GM added the return line for vapor lock resistance. It's the older rigs that don't have it. I would keep it... The return is incorporated into the mechanical fuel pump head and is not easily incorporated into an electric pump setup... Yet another reason to stay with mechanical.

I have found my relationships with Edelbrock and Holley Carburetors to be a mixed blessing... actually more of a curse. The Rochester Quad is a dead reliable unit when rebuilt properly. It's good to 750CFM and more on some models.

[PancakeMix]

I actually managed to find a used poly gas tank online for 50 bucks. It's drivers side, so whatever, I'll just mount it there and deal with the extra bends.

I'm eliminating a lot of extra junk that was there originally.

Tank selector is gone. Second tank is gone. Have brand new fuel filter that will be hooked directly to the new electric fuel pump (both have threaded ends). And I'm going to get a hard fuel line kit for my carb.

So the only rubber in the system will be from the tank to the fuel pump/filter setup. Everything else will be hard lined and threaded. I'm really excited to get this going.

Today I finished removing all my old fuel lines -- two were connected to themselves with a few inches of rubber hose...? Put my fuel pump block off plate on. And I'm going to get the old tank brackets cleaned up and painted later this evening.

[hatzie]

The only difference between driver and passenger side is the position of the fuel sender pipes.
The fill holes are centered in the end of the tank and the straps just need to be turned 180° on the tank so they bolt on with the fill point on the rear.
Where you will get into trouble is the fill neck. It makes using an early tank on a later chassis or later tank on an early chassis difficult but not impossible. Don't remember off the top of me head where year the split is.

[PancakeMix]

DONE:
-rubber line from carb to fuel filter
-rubber line from fuel filter to nicopp
-nicopp line from top of engine run down to frame rail, behind alternator
-union placed in open area by frame rail
-nicopp routed in frame rail to first crossmember of bed
-compression fitting directly into fuel pump
-fuel pump directly connected to second fuel filter
-rubber line from fuel filter over to the poly tank
-new 90 degree rubber fill neck
-new vent tube
-new grounding strap
-new tank straps, inserted into bicycle inner tube

NEED:
-fuel sending unit to get shipped on Monday

TO DO:
-wire up a switch. I want to use the old tank selector as kind of an anti theft. One tank turns the pump on, the other tank turns the pump off.
I know it would be better to wire it into the oil pressure switch, but I don't drive this truck a lot and want to be able to prime the line after it sits for a while.

-figure out how to hook up the fuel gauge. I suck at schematics/electronics. It appears that the pink wire goes to the fuel gauge?

-on this sending unit, the black wire is ground I think. Do I hook the pink wire to the round terminal on top?

[hatzie]

The round terminal is the sender.
I don't see a vapor or fuel return fitting... This sender will work with a vented filler cap.

[PancakeMix]

Yea, that's the plan with the gas cap.

When I originally got the truck, it had an earlier single line mechanical fuel pump. The return lines were there, but rotted out and at the front of the truck someone ran a small piece of rubber tube from one to the other and capped them off basically.

I just wanted this to be as simple and leak free as possible.