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Just completed my return system. I built a custom aluminum bucket (surge tank) with two pumps. The aeromotive 340's have check valves in them. However, I wasnt aware (well I assume it needed) that the return side needs a check valve as well. Its not 100% necessary but in my case i think it is. When I cut the car off, it loses pressure so the cranking time is a touch longer. Probably not a big deal but i'd rather it fire immediately like normal. Also, with having no check valve, when i disconnect the return under the tank, it starts a siphon effect and starts pouring fuel out. the only way to avoid it is to have the check valve right at the pump connection or disconnect the line at the regulator front and lightly blow compressed air in the return line to force the fuel out the line and back into the tank.
Anyone else use a check valve? I already ordered a vibrant brand one.
I canceled the vibrant check valve. I had a brain fart and realized that the only thing it will do for me is prevent a siphon effect when I disconnect the return line. It won’t help hold fuel in my lines the way I need it to. So.....
I realized I need a check valve that has a cracking pressure. Maybe 5-10psi so it’ll keep the lines full of fuel but won’t necessarily be under pressure. Soon at I hit the key, the pressure should come up immediately. Yea, I’m being picky but I want it how I want it. Jegs has a valve like I need but they are out of stock. Ugh.
Ok well I answered my own question. I put the car back together. Drove it around. It cranks right back up after sitting for a short time. Then I waited till the next day. Cranked it, does take a tad longer but not a big deal. I did order a check valve from jegs and I’m going to put it on later. I keep thinking about how it caused a siphon effect when I pulled the line off the return. That makes me nervous. In the slim chance that the line gets damaged or punctured, it has the potential to make a very dangerous situation. The check valve will prevent that.
Mine does this too. It's actually pretty bad if the car sits in the trailer between races, like a few days. I have to prime the pump 4 or 5 times and then crank it a little while fluttering the gas pedal. If the car has only been sitting a few hours it cranks right up, over night is a little longer. I'm interested if your check valve in the return with a little cracking pressure is the fix. I have a nasty fuel rail/line setup on a double pumper Squash system. I would have thought the FPR would hold the pressure at start up, but if it's siphoned out by the return and there is air in the supply side of the system, that is probably it.
So the check valve would go on feed side or return side?
feed side has a check valve in the pump already. The return side is getting on. However. I realized after posting this that it won’t work the way I want it to. I was thinking the check valve would hold the fuel in the return line, eliminating longer starts if I don’t let the pump prime. Well if I did that, the fuel wouldn’t flow through it either. So....
I got a check valve that advertises 5psi open pressure. So if it just keeps fuel in the line, the starts will be faster. I haven’t installed it yet so I’m not sure it’ll work. Im not happy with the sealing of it and the quality of it. The spring pressure sucks and it doesn’t seem like it would hold any fuel in the line.
If I turn the key in, wait a second or so and then turn the key, it fires right up. If I just turn the key quickly, like I’ve done my whole 27+ years of driving....then cranking time is much longer. And I don’t like that. It’s like 2 seconds of cranking which sounds like I’m cranking a car in the cold on e85. I just don’t like it. So I’ll figure it out. It runs for now and gets the amount of fuel it needs so I’ll live with it for now. Till I have more time to fool with it.
Thanks for the reply. I’m in the process of rebuilding my car and one aspect is the fuel system. Just tying to absorb as much as I can and do things once hopefully. I bought the Racetronix kit to switch to a return style system, but see no mention of check valve.
my cars sit a lot so I’m use to key in and priming pump once or twice. I will try as is
Maybe I'm stupid but I don't understand how a check valve will help. All it does is to only allow flow in one direction. In this case the flow is from the regulator back to the tank. The siphoning scenario you mentioned would involve fuel moving in the same direction wouldn't it?
Another thought, again maybe I'm out to lunch but shouldn't the regulator stop flow through the return line when the system pressure is less than the preset?
Maybe I'm stupid but I don't understand how a check valve will help. All it does is to only allow flow in one direction. In this case the flow is from the regulator back to the tank. The siphoning scenario you mentioned would involve fuel moving in the same direction wouldn't it?
Another thought, again maybe I'm out to lunch but shouldn't the regulator stop flow through the return line when the system pressure is less than the preset?
one thing is if I disconnect the return line below the tank, it siphons fuel out the tank. Continually. If the line gets damaged, that could be disaster.
next. When I cut the key off, it creates a void of fuel in the return, so if I get a check valve that lets fuel flow back into the tank but has a crack open pressure 1) it will too the siphoning if a line comes off of get damaged 2) will hold more fuel in the return line when its cut off so it will pressurize faster. Resulting in faster starts. I can video it and show you exactly what I mean how much longer it takes to crank
Sounds to me like you have a problem with your system.
Afaik there should be no flow through the return if the system is below the pressure preset. The regulator should only allow flow into the return if it needs to reduce the system pressure.
I'm thinking your reg is not working properly or the system is not routed correctly.
Sounds to me like you have a problem with your system.
Afaik there should be no flow through the return if the system is below the pressure preset. The regulator should only allow flow into the return if it needs to reduce the system pressure.
I'm thinking your reg is not working properly or the system is not routed correctly.
nah. There no problem with my system. It’s normal. I called aeromotive and confirmed. I talked to a couple buddies and there’s does the same. I’m picky. If you turn the key forwrd and wait one second, it’s fine and primes up.
Mine is way worse, so I subscribed to see if someone tried this.
My setup is as the drawing shows. It's a nasty fuel line and rail setup, -8 size, fed by a squash dual 450s on E85. It takes 4 or 5 primes and turning it over while fluttering the gas pedal to start if it has been too long, like a week. Overnight, it is just prime, then it'll start pretty quick. Within a few hours it starts like stock.
.
FPRs don't seal perfectly. They are made to open quickly and adjust to load. They do hold pressure for a while, but they all bleed down if there is a return. I think he is thinking that the check valve is a better sealing device and with a low cracking pressure of ~5psi or something, it could stop the siphoning back to the tank. I'll give it a try when I get a chance if no one else does.
Mine is way worse, so I subscribed to see if someone tried this.
My setup is as the drawing shows. It's a nasty fuel line and rail setup, -8 size, fed by a squash dual 450s on E85. It takes 4 or 5 primes and turning it over while fluttering the gas pedal to start if it has been too long, like a week. Overnight, it is just prime, then it'll start pretty quick. Within a few hours it starts like stock.
.
FPRs don't seal perfectly. They are made to open quickly and adjust to load. They do hold pressure for a while, but they all bleed down if there is a return. I think he is thinking that the check valve is a better sealing device and with a low cracking pressure of ~5psi or something, it could stop the siphoning back to the tank. I'll give it a try when I get a chance if no one else does.
mine is done just like that. I will be doing it for sure but I may get a different valve than the one I got from jegs. It’s kinda cheesy how it’s made.
Bleed down is immaterial as long as pressure builds up quickly when key goes on.
There is no reason to retain pressure once the engine shuts off.
it’s not immediate and if I forget to prime it, it’s embarrassing to have a nice car turning over and over an excessive amount of time to get it started. My preference, and I’m going to fix it. No matter what it takes.
nah.
1. There no problem with my system.
2. It’s normal. I called aeromotive and confirmed.
3. I talked to a couple buddies and there’s does the same.
4. I’m picky.
5. If you turn the key forward and wait one second, it’s fine and primes up.
5 reasons not to mess with a good NORMAL, same-as-everyone-else system.
Get picky on REAL issues...
Aight fellas. I did a short video for you. First in the video is a hot start after sitting for about 2 hours. I did not let it prime. Do note that if I let it prime, it cranks exactly like it does in the cold start. Cold start with a prime is the second clip in the video.
Your second start sounds totally normal. You just had the key on a second before cranking. That's how it's done.....
You need to build pressure first.
ummm yea, it sounds normal. Because I primed it. I don’t want to have to prime it. I forget because for the past 27 years I’ve been driving, I never had to prime anything. The first start is how I normally start the car. You know, put the key in and turn it. It’s ok if you are ok with priming it. You might be used to that. I’m not, and I don’t like it and no one can convince me to like it. Ok. Ok. Lol.
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Retern line needs a check valve? 
