Carbed 3.5 V8 Fuel Vent Line Question

dcg

Well-known member
I have a V8 German spec ‘84 110 CSW. I’m sticking with the inline fuel pump & filter mounted on the outrigger in its original location. There is a small line of some kind coming from the front of the truck. It was mounted to the “L” bracket on the frame with plastic clips. When I removed the pump that was there, it was not connected to anything. I attached photos of the bracket, line & parts book pages. When looking in the parts book, the “Fuel Pipes” are all there (1-4, p378). The fifth line is not listed or shown. There is a note on the same page that mentions “Vent Pipes”… could it be that? Does it connect at all? It is angled towards the fuel filter. Looking at page 338, is it the "Vent Pipe" (items 11 & 12)? I did not trace where the line connects to the engine.
 

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NMEXPAT

Active member
It is probably the fuel return line. I have an 1987 110 with a v8. Mine had a fuel line going from the tank to the engine and a return line from the engine to the fuel tank. The return line to mine was not connected near the engine and blocked off. When I changed out the intake manifold and converted to 4 bbl carburetor, I connected the fuel return line to an aftermarket pressure regulator. Opinions differ on this. I have an internal fuel pump, which is always on, which should be the same operational situation for an external pump. I figured it was better to circulate fuel all the time with little back pressure.
 

Napalm00

Technical Excellence Contributor
Recirculating is much better, easier on the pump, you also get cooler fuel since the unused fuel does not "deadhead" in the carb. No real downsides
 

DPdotCOM

Member
confirmed as others said, it's def a fuel return line.

I avoided doing a Sniper EFI bc i didn't want to deal with running a return line, then I discovered it while installing my Holley :cautious:
 

dcg

Well-known member
I've been away for a bit... sorry for the delayed response. Thanks for the input. I still need take a look at the truck to see where it terminates in the engine bay. If there is already a "spill line" from the engine to the tank (#4 in the manual photo above). What would this be? This internal diameter is at least half of the fuel lines.
 

Roverman2010

Well-known member
Having had many carbed rovers the return line is a smaller dia just gives that bit of back pressure. make sure your inline pump is low pressure not more than 5psi. Those vent lines in that picture? There is a vent line on each float bowl for each carb that just dead ends lower than the exhaust (carb flooding due to stuck needle vavle) that picture is misleading as a vent there does nothing.
 

dcg

Well-known member
The pump is a Facet. When I got the truck, there was an after market pump installed. The small return was disconnected. I didn't discover it until I pulled the 2nd row floor. Where would that small return line connect? I don't see a Y pipe in the parts book. The filter to engine fuel line fitting was cut off, so was not able to observe the original configuration. I obtained a NOS tank to pump fuel line, but there is only one fitting that connects to the inlet on the pump.
 

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Roverman2010

Well-known member
Most of the ones I have and seen, you have the fuel (from Pump) connects to the first carb, jump hose/pipe to the second of which the retune is tee'd off of and returns to tank. I'll get you a picture if you need?

did some art to the picture
2021-09-09_LI.jpg
 
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