Fuel Vapor Separator with Electric Fuel Pump?

[PurpleBeeper]

I've had some periodic vapor lock issued on my 440 six pack. I'm running a Holley electric blue pump. Will adding a vapor separator help me? THANKS

 

[lewtot184]

I've had some periodic vapor lock issued on my 440 six pack. I'm running a Holley electric blue pump. Will adding a vapor separator help me? THANKS

yes. should eliminate vapor lock. your electric pump will live longer with a return.

 

[threewood]

It should help. With an electric pump, get a regulator with return port. I am using a Holley black pump to the regulator then to a fuel filter with vapor return port. Seems to work.

 

[PurpleBeeper]

It should help. With an electric pump, get a regulator with return port. I am using a Holley black pump to the regulator then to a fuel filter with vapor return port. Seems to work.

Please explain a little more. I've never run the "factory" type fuel vapor separator or a return line. I've also never seen a fuel filter with a vapor return port.

I'm currently running two Holley blue pumps with the standard regulator they come with, both set at 6psi (mechanic fuel pressure gage for both pumps mounted on cowl). The second pump is for the nitrous only. I have one of those "dual line sumps" welded to the bottom of a stock fuel tank, so my stock 3/8" fuel nipple at the tank (fuel sending unit) is capped off.

I am running the stock tank vent. What I see is that "sometimes" while driving the engine fuel pressure gage starts to drop to about 2psi all of a sudden, then bounces back up to 6psi & repeats. I changed the engine fuel pressure gage, no change. I changed the fuel filter (after the regulator under the hood), no change. I also pulled over while the engine fuel pressure was down at 2psi & quickly un-corked the gas cap, no change.

I'm about to change the engine's Holley blue fuel pump, just to be sure, but I also want to add other fixes as needed. This engine has a long history of vapor lock. I had to drive it home with a rag full of ice on the middle carb many years ago.

 

[HEMI-ITIS]

Fuel slosh will cause that as well.That is why they like to use foam in fuel cells.

 

[62 Dart Convertible]

I've also never seen a fuel filter with a vapor return port.

You have now - (Wix 33040 = 2 x 5/16" & 1/4" return with built in return orifice, Wix 33041 = 2 x 3/8" & 1/4" return with built in return orifice)

 

[PurpleBeeper]

Fuel slosh will cause that as well.That is why they like to use foam in fuel cells.

Hey Hemi, please explain this. My fuel pressure drop problem normally happens when I'm sitting at idle at a stoplight. I don't think my fuel is sloshing too much when it happens.

 

[PurpleBeeper]

You have now - (Wix 33040 = 2 x 5/16" & 1/4" return with built in return orifice, Wix 33041 = 2 x 3/8" & 1/4" return with built in return orifice)
View attachment 547145

Thanks 62 Dart. OK, so if I'm running one (or two I guess) of these filters & a return line to the stock tank's fuel outlet at the sender (I supply fuel to both pumps with a dual outlet sump on the stock fuel tank), will that work for me to eliminate any "vapor lock"? Is this doing the same thing as the stock-style 440/hemi vapor separator?

Lastly, what do I do about the other nitrous-system supply fuel line? Can I "T" the two fuel returns? Is there no way for a the 2nd fuel pump for the nitrous to "vapor lock"? (that's what I'm thinking)

My "gut instinct" would be to ONLY use this on the engine's fuel pump fuel line & run the return fuel back through the fuel sender (capped off now since I'm pulling fuel out of the dual-outlet sump). OR, would that actually create "fuel slosh" like Hemi is talking about?

FYI- I wired in the new engine Holley blue pump, but haven't tested it yet (clutch/trans out of the car at the moment)

 

[HEMI-ITIS]

Hey Hemi, please explain this. My fuel pressure drop problem normally happens when I'm sitting at idle at a stoplight. I don't think my fuel is sloshing too much when it happens.

Your right.'if you just roll up to a stop,unless your real low then slosh should be a non issue.

 

[62 Dart Convertible]

Thanks 62 Dart. OK, so if I'm running one (or two I guess) of these filters & a return line to the stock tank's fuel outlet at the sender (I supply fuel to both pumps with a dual outlet sump on the stock fuel tank), will that work for me to eliminate any "vapor lock"? Is this doing the same thing as the stock-style 440/hemi vapor separator?

Lastly, what do I do about the other nitrous-system supply fuel line? Can I "T" the two fuel returns? Is there no way for a the 2nd fuel pump for the nitrous to "vapor lock"? (that's what I'm thinking)

My "gut instinct" would be to ONLY use this on the engine's fuel pump fuel line & run the return fuel back through the fuel sender (capped off now since I'm pulling fuel out of the dual-outlet sump). OR, would that actually create "fuel slosh" like Hemi is talking about?

FYI- I wired in the new engine Holley blue pump, but haven't tested it yet (clutch/trans out of the car at the moment)

Well I had massive problems with vapor lock and one of these filters cured it for me. I would say your observed pressure drops are proof vapor is presenting at the carb float valves. To my thinking, the vapor separator should be as close to the carb as possible, and the factory set up located just after the mech pump is odd. I'm convinced my problems were in the steel line from the pump up and over the rocker cover to the carb so a V S right after the pump just wouldn't help. I would put one in both fuel supplies, and I'd say teeing the 2 return lines would be fine. Alternatively, as threewood suggested, you could use a fuel regulator with a return port, but again I'd suggest it be located as close to carb as possible. A 3 port filter or 2 will certainly be less costly to try first though!

 

[747mopar]

A return line from a regulator (requires return style regulator) to me is the best option. All this does is keeps the fuel moving so it never sits idle next to things like the headers plus it helps the fuel pump by allowing flow vs dead heading it.

 

[PurpleBeeper]

A return line from a regulator (requires return style regulator) to me is the best option. All this does is keeps the fuel moving so it never sits idle next to things like the headers plus it helps the fuel pump by allowing flow vs dead heading it.

You make a good point. I don't have return style regulators though. I may try the 3-hole fuel filters first since I'm sure they are cheaper. I am definitely "dead heading" my fuel with my current setup, and certainly at idle the fuel isn't moving very fast & is likely getting cooked over the hot engine and/or in the carburetors themselves.

Back when I had the really bad vapor lock problem (ice in a shop rag to get me home) I solved that problem by adding insulating spacers under all 3 carburetors (paper/aluminum/paper/aluminum type) and it seemed to work. Now, I have nitrous plates under the carbs & my hood clearance is TIGHT, so the heat spacers had to go. Now that I think of it, I think I might just put those heat spacer back under the middle carb since it doesn't have a nitrous plate (yet anyway). If all else fails, I will see if I can find some return-style regulators.

I guess my questions about the "T" for the fuel return lines is because I'm not sure what would happen if I "T" two return lines together. Maybe I'm worried about nothing. Plus, I don't think I would get (hope not) vapor lock in the nitrous fuel line. FYI- I have rubber fuel hose going from both regulators to the carbs/nitrous & I have them suspended as high as I can up in the air so they're not very close the engine or headers especially. Maybe I should insulate my fuel lines too???

FYI- I just ordered two 33041 WIX filters to give that a try first. I probably won't know if they do the job until next summer sitting in traffic though.

 

[747mopar]

I bought an insulated sock (hose) and slid it over 4ft of my fuel line where it passes by the header.. it helped. I have ALMOST zero issues with mine but a return line is next.

 

[62 Dart Convertible]

You make a good point. I don't have return style regulators though. I may try the 3-hole fuel filters first since I'm sure they are cheaper. I am definitely "dead heading" my fuel with my current setup, and certainly at idle the fuel isn't moving very fast & is likely getting cooked over the hot engine and/or in the carburetors themselves.

Back when I had the really bad vapor lock problem (ice in a shop rag to get me home) I solved that problem by adding insulating spacers under all 3 carburetors (paper/aluminum/paper/aluminum type) and it seemed to work. Now, I have nitrous plates under the carbs & my hood clearance is TIGHT, so the heat spacers had to go. Now that I think of it, I think I might just put those heat spacer back under the middle carb since it doesn't have a nitrous plate (yet anyway). If all else fails, I will see if I can find some return-style regulators.

I guess my questions about the "T" for the fuel return lines is because I'm not sure what would happen if I "T" two return lines together. Maybe I'm worried about nothing. Plus, I don't think I would get (hope not) vapor lock in the nitrous fuel line. FYI- I have rubber fuel hose going from both regulators to the carbs/nitrous & I have them suspended as high as I can up in the air so they're not very close the engine or headers especially. Maybe I should insulate my fuel lines too???

FYI- I just ordered two 33041 WIX filters to give that a try first. I probably won't know if they do the job until next summer sitting in traffic though.

I added more carb insulators too in case fuel was boiling in carbs, but my observations were that when I had a problem the carbs were never really that hot and that they were actually bone dry rather than full of boiling fuel.

Why would you assume fuel won't vapor lock in line to nitrous system? A vapor separator in there would be cheap insurance against lean out. Install filter with 3rd nipple clocked at 12:00 position as bubbles always rise.

Is your intake heat riser cross-over blocked off?

 

[PurpleBeeper]

I added more carb insulators too in case fuel was boiling in carbs, but my observations were that when I had a problem the carbs were never really that hot and that they were actually bone dry rather than full of boiling fuel.

Why would you assume fuel won't vapor lock in line to nitrous system? A vapor separator in there would be cheap insurance against lean out. Install filter with 3rd nipple clocked at 12:00 position as bubbles always rise.

Is your intake heat riser cross-over blocked off?

Well, my carbs do get hot to the touch & I don't really have much metal line. Since the nitrous doesn't go into the carbs, I was thinking it wouldn't get as hot. It "seems" like the only fuel line that could get hot is where it comes up towards the engine along the passenger inner fender. I've kept it as far away as possible from the header on that side. I like 747's idea of a fuel line insulator.

No, the heat cross-over is open & the intake is cast iron. The nitrous plates are aluminum blocks, so I don't think they insulate the carbs like the aluminum/paper/aluminum/paper spacers or a thick cardboard type of heat spacer. I'm thinking I might need a IR heat gun???

 

[747mopar]

Any added gasket separation will aid in eliminating heat transfer to the carbs, your nitrous plates should help. Nowadays with the fuel we have at the pump I block the heat transfer on every build, next time you have the intake off I'd block it off.

 

[62 Dart Convertible]

Next time you have the intake off I'd block it off.

First thing I'd do before anything else!!