Rebuilding the Fuel System

RBBailey

Well-known member
Callsign: KF7KFZ
I'm toying with a total rebuild of the entire system. I suppose I could be totally wrong here, but I feel like there is air or contaminate getting in, which is what is causing my on-again, off-again rough running. Other than that, here is why:

  • Fuel filler tube leaks at the seams
  • Fuel cap leaks
  • The seal between the top of the filler tube and the body panel leaks.
  • The vent tube leaks
  • The top of the tank leaks from where the pump enters.
  • The side of the tank leaks from where the sender enters.
  • The metal fuel lines along the frame to under the front passenger floor are crusty looking.
  • From the metal lines, standard rubber hoses now run to the cam pump on the block, then to the fuel filter.
  • The engine starves of fuel while there is still about 5 gallons in the tank.
That is to say, the whole thing seems iffy.

As of now, it is a 1988 V8 system that has simply had the rubber hoses attached at the engine end to run to the cam pump on the block.

So... What are my options? What kind of lines should I get to replace the old metal lines? Do I need a new tank to make a conversion work? Other than the leaks at the gaskets, how will I know if the tank needs to be replaced? Part numbers? All the little things that I'm bound to forget and end up 5 minutes from done, but have to wait 4 weeks for shipping?
 

RBBailey

Well-known member
Callsign: KF7KFZ
Here's an example of what worries me about trying to go to a stock system.

I can't imagine ever getting this hose to fit right. My fuel filter is not up front on the wing, it is between the heater box and the overflow tank. I think I can move it without trouble, but is there any reason why I can't use rubber fuel hose here? (It's what I'm using now, actually. So the question is more like: Should I be pulling all the rubber hose lines that are in use now, and try to get stock from tank to engine?)

http://search.cartserver.com/search/search.cgi?cartid=s-5540&category=RovahFarm&maxhits=20&keywords=ETC6902+&go=GO!
 

Napalm00

Well-known member
I did a whole massive post on this exact thing for my 200tdi.

Long story short you can replace everything with diesel rated 5/16 rubber line and have no issues. Most of the threaded fittings are 1/2x20 tube and olive and they can be swapped for barbs.

Or you can go buck wild and replace everything with braided stainless like I did. All new filter head, pre-filter and an fittings

Take a gander alot to read :https://nas-row.com/showthread.php?t=1347
 

RBBailey

Well-known member
Callsign: KF7KFZ
Can?t get a pick of the pickup on the top, but here is the side. What are the extra electrical ends on this harness for?

I?m looking at the Pegasus Racing fuel line and connections. But I do need to go look at your thread to decide for sure.
 

Attachments

Napalm00

Well-known member
Does that side connection have a fuel line coming from it? And two wires and a ground stud?

The three prong plug and socket isn't stock, who knows what that is
 

Napalm00

Well-known member
Nevermind I think I see what they did. Looks like you have a 19gallon gas/diesel two hole early tank. They converted the top gasoline style pickup and level sender to diesel and must be using one of the vent lines as a return.

This is why you run dry 5gallons high.

You need Ntc2156 and it's gasket to convert to top return
You need prc8463 and. It's gasket and lock ring to convert to side pickup and fuel level

Then all the hoses and shit
 

RBBailey

Well-known member
Callsign: KF7KFZ
I believe The side sender is wired to the gauge. But I can check that.

The return line is opposite this, and the pickup line comes out of the top center.
 

RBBailey

Well-known member
Callsign: KF7KFZ
When you say converted to diesel...

Nothing was done back here that I’m aware of.
 

Napalm00

Well-known member
You will also have to extend some of the tank wiring and. Block off the vent they used as return. This also may be a reason why you had air bubble issues in your fuel. It was just being dumped into the tank from above instead of below the fuel level line... Causing turbulence
 

RBBailey

Well-known member
Callsign: KF7KFZ
Your truck was gas originally and is now a tdi? Correct?
Yes.

I'll inspect this thing this evening.
I don't know enough about how this works to know why simply changing the front end to diesel means it runs out of fuel. Interesting.
 

Napalm00

Well-known member
Because they left the gas pickup that is supposed to have a filter and sending unit on it. Then they rigged a return line through the vent for rrc applications. So you are drawing fuel from too high in the tank and returning it in the wrong place.

Pick up should be in the side, return in the top, extra vent blocked off as it isn't used in this application.

Your side Image shows a blanking plate behind the lock ring, this is how i know because my truck was setup the same way nine years ago when it came over.

Long story short they cheaped out. Trust me the part numbers I listed will set you straight.

You can then run 5/16 rubber line everywhere with clamps and be gtg. Just cut the old plastic line off the metal end tubes and clamp your new hoses to that. No new hardware to buy!

Or

Do all that crazy shit in my thread (it has pics of how the side pick up is supposed to look)



Correct side pickup with sender wires, ground stud and a 8mm tube output (can't see the tube aluminum fitting is on it)
 

RBBailey

Well-known member
Callsign: KF7KFZ
Yeah, I trust you.

I'm just trying to figure why the same pickup I was using no longer works just because diesel instead of gas is now in the tank. Nothing back there was changed.
 

Napalm00

Well-known member
Probably the extension that the rigged on the end to replace to pump broke off or the filter did, or the pump did, or It's clogged

Bad news is your gonna have to drop the tank... Its a shit one man job and the hardware is very rust prone
 

RBBailey

Well-known member
Callsign: KF7KFZ
You need Ntc2156 and it's gasket to convert to top return
You need prc8463 and. It's gasket and lock ring to convert to side pickup and fuel level
If I can not work for 12 hours for just one day I might be able to put together a parts list, and make one order, and be ready to do this.

Since I am one of these people who basically needs to have the whole thing understood and visualized before I can even bring myself to buy the parts; let me get this straight: I need to use the parts above to get the return to drop down into the center bottom of the tank (where the V8 sender and pickup currently is) so as not to create bubbles in the fuel, and to move the pickup and sender over to the drivers side ? am I right that the sender is also the pickup line on PRC8463?

Then I get new hoses and fittings to replace my crusty lines that run to the engine bay.

Q: am I going to have trouble getting fittings to fit the standard fuel filter housing? Can?t afford an upgraded housing right now.

Also, I get why the proper set up is going to work, but I still can?t figure out why the current V8 style pick up causes me to run out of fuel at 1/4 tank.
 

Napalm00

Well-known member
...
If I can not work for 12 hours for just one day I might be able to put together a parts list, and make one order, and be ready to do this.

Since I am one of these people who basically needs to have the whole thing understood and visualized before I can even bring myself to buy the parts; let me get this straight: I need to use the parts above to get the return to drop down into the center bottom of the tank (where the V8 sender and pickup currently is) so as not to create bubbles in the fuel, and to move the pickup and sender over to the drivers side ? am I right that the sender is also the pickup line on PRC8463? Essentially yes and yes

Then I get new hoses and fittings to replace my crusty lines that run to the engine bay. you only need new hose, cut the plastic and rubber lines off the metal "pipes" and fittings and leave the fittings in place, dont even need to use a wrench here. Slip the 5/16 hose over the ends of the existing fittings and clamp them on

Q: am I going to have trouble getting fittings to fit the standard fuel filter housing? Can?t afford an upgraded housing right now. See above

Also, I get why the proper set up is going to work, but I still can?t figure out why the current V8 style pick up causes me to run out of fuel at 1/4 tank.
Because the v8 pickup is designed to have a electric pump hanging off the end of it, it has been removed or bypassed making it shorter or it has degraded and fallen off. The Vent line they they are using as a return just splashes the fuel into the tank from above the "waterline". The correct return puts the returning fuel under the "waterline" causing less turbulence. It also keeps sediment away from the pickup as they enter and exit near the same area (the depression in the center of the tank)
 

Napalm00

Well-known member
sorry for the funky formatting on mobile.

other notes:

You will need to drop the tank

buy Diesel rated fuel line (does not need to be rated for fuel injection)

You may also need a lock ring for the side sender/pickup

you will probably need the metric machine screws for the top of the tank as they rust often

You will need to block off the old return/vent line currently in use

When installing the new sender/pickup make sue that the pickup tube is at the bottom of the tank ( may need to be bent into place)

Dropping the tank may be a bitch depending on the rust on the fasteners

Depending on your fuel filter housing type the top connection to the banjo bolt may be a huge pain in the ass to clamp to the hose, you may want to leave this short line

Use properly sized fuel injection clamps, they are much more secure than standard worm clamps.


When installing the return line clamp it in place and screw it down before lifting the tank back into place, leave the sender off until the tank is bolted up.
 
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