Fuel slosh/starvation solutions for HF pump owners.
Cypher2k
1 - 19 of 19 Posts
Re: Fuel slosh/starvation solutions for HF pump owners. (Cypher2k)
Funny you mention this, I just came across the thought of a surge tank and posted on it in the FI forum a week or two ago. Seems like the perfect solution, you're right. I am waiting to see what someone is going to do about in-tank pump starvation before I seriously look into having a surge tank, mocked up on a stock airbox. I purchased a stock airbox a week ago to see exactly what this project might entail.
Think about this, take a Walbro 255lph in-tank pump. 255lph is rated @3bar I believe. Stick another or the Bosch pump on the surge tank and there's no way the in-tank pump, will run out of fuel before the tank is empty. You'll never run into a fuel starvation problem because you have a quantity of fuel under the hood. Because the Walbro is under no pressure, it will always flow more that the second pump under pressure.
Funny you mention this, I just came across the thought of a surge tank and posted on it in the FI forum a week or two ago. Seems like the perfect solution, you're right. I am waiting to see what someone is going to do about in-tank pump starvation before I seriously look into having a surge tank, mocked up on a stock airbox. I purchased a stock airbox a week ago to see exactly what this project might entail.
Think about this, take a Walbro 255lph in-tank pump. 255lph is rated @3bar I believe. Stick another or the Bosch pump on the surge tank and there's no way the in-tank pump, will run out of fuel before the tank is empty. You'll never run into a fuel starvation problem because you have a quantity of fuel under the hood. Because the Walbro is under no pressure, it will always flow more that the second pump under pressure.
Re: Fuel slosh/starvation solutions for HF pump owners. (Cypher2k)
I came up with somethinf simple yet effective. The pic enclosed is pretty self explanitory. This reservoir would be mounted Horizontally rather than vertically. The inlet and outlet are at the the bottom allowing the tank to flood with a bleeder at the top to bleed air/gas back to the tank. The bleeder of course will have a check valve.
![Image]()
I came up with somethinf simple yet effective. The pic enclosed is pretty self explanitory. This reservoir would be mounted Horizontally rather than vertically. The inlet and outlet are at the the bottom allowing the tank to flood with a bleeder at the top to bleed air/gas back to the tank. The bleeder of course will have a check valve.
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Re: Fuel slosh/starvation solutions for HF pump owners. (Cypher2k)
A simple solution would be to make a new "cup" for the thing to set down into. An aluminum can about the same size of a small coffee can with three of four 1/2 inch holes in the sides (right near the bottom) would do the trick.
A simple solution would be to make a new "cup" for the thing to set down into. An aluminum can about the same size of a small coffee can with three of four 1/2 inch holes in the sides (right near the bottom) would do the trick.
Re: Fuel slosh/starvation solutions for HF pump owners. (MRP2001GTi)
yea you are right... but that would be so GHETTO... haha
| Quote, originally posted by MRP2001GTi » |
| A simple solution would be to make a new "cup" for the thing to set down into. An aluminum can about the same size of a small coffee can with three of four 1/2 inch holes in the sides (right near the bottom) would do the trick. |
yea you are right... but that would be so GHETTO... haha
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Re: Fuel slosh/starvation solutions for HF pump owners. (MRP2001GTi)
Man, you're all about some "coffee can engineering" aren't ya?
![Image]()
jk
| Quote, originally posted by MRP2001GTi » |
| A simple solution would be to make a new "cup" for the thing to set down into. An aluminum can about the same size of a small coffee can with three of four 1/2 inch holes in the sides (right near the bottom) would do the trick. |
Man, you're all about some "coffee can engineering" aren't ya?
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Re: Fuel slosh/starvation solutions for HF pump owners. (barelyboosting1.8t)
Just not into over engineering.
![Image]()
Fuel tank baffles are best when simple and I drink a lot of coffee...........LOL
| Quote, originally posted by barelyboosting1.8t » |
Man, you're all about some "coffee can engineering" aren't ya?
|
Just not into over engineering.
Re: Fuel slosh/starvation solutions for HF pump owners. (Cypher2k)
Short of going in to the tank and putting a sump, baffle or foam in the tank to slow down sloshing, a swirl pot is probably the best idea. For FI cars, a swirl pot will need 4 ports. Three at the top, one at the bottom for best results. Feed line to the pot, one feed line from the pot to the injector rail, a return line to the pot from the injector rail, and a return line from the pot to the tank. You the transfer pump can keep up with the volume, as it's not under pressure and flows much higher rates generally. I was going to run a swirl pot setup on the racecar, but the intank pump on the Mk2 is more than adequate for my carbs, so it's not a big deal, but she does sputter pretty early on those wonderful 1/8 tank fuel loads even in the mk2. The CIS-E system on the Mk2s, had an accumulator system, so that was never an issue with any Mk2. Also, it's better to mount the swirl pot in a vertical fashion, as there will be less of an effect of the G loading from cornering on a vertically oriented cylinder, than if it was on it's side.
Modified by RaceJetta at 2:35 PM 3-11-2004
Short of going in to the tank and putting a sump, baffle or foam in the tank to slow down sloshing, a swirl pot is probably the best idea. For FI cars, a swirl pot will need 4 ports. Three at the top, one at the bottom for best results. Feed line to the pot, one feed line from the pot to the injector rail, a return line to the pot from the injector rail, and a return line from the pot to the tank. You the transfer pump can keep up with the volume, as it's not under pressure and flows much higher rates generally. I was going to run a swirl pot setup on the racecar, but the intank pump on the Mk2 is more than adequate for my carbs, so it's not a big deal, but she does sputter pretty early on those wonderful 1/8 tank fuel loads even in the mk2. The CIS-E system on the Mk2s, had an accumulator system, so that was never an issue with any Mk2. Also, it's better to mount the swirl pot in a vertical fashion, as there will be less of an effect of the G loading from cornering on a vertically oriented cylinder, than if it was on it's side.
Modified by RaceJetta at 2:35 PM 3-11-2004
Re: Fuel slosh/starvation solutions for HF pump owners. (drm916)
After dealling with this issue for a few months, I put a stock pump back in the tank and ran an inline pump, problem solved.
I was under the impression that all of the "drop in" intank pump replacements didn't have this issue.
After dealling with this issue for a few months, I put a stock pump back in the tank and ran an inline pump, problem solved.
I was under the impression that all of the "drop in" intank pump replacements didn't have this issue.
What I don't undestand is why wouldn't happen with the inline. Wouldn't the rate of suction be the same if not more. The question is does an inline run dry on a 1/8 th tank in hard corners/hard accelaration b/c of the design or is it b/c of the rate of suction?
I personally have not had this experiance, but I am inclined to look into it.
I personally have not had this experiance, but I am inclined to look into it.
Re: (Don R)
The stock pump has provisions to keep this from happeing. It has two pickups. One picks up from the bottom of the tank. The other pickup gets is fuel from inside the can, that the return line always keeps filled up. So no matter what the situation, unless you have no fuel, the pump is always submerged in gas.
It's like the stock pump has a built in swirl pot, sort of.
Unless the pump is a complate 100% identicle replacement for the stock pump, you pretty much have to modify the can in some way, or at the very least, you lose that second pick up.
The stock pump has provisions to keep this from happeing. It has two pickups. One picks up from the bottom of the tank. The other pickup gets is fuel from inside the can, that the return line always keeps filled up. So no matter what the situation, unless you have no fuel, the pump is always submerged in gas.
It's like the stock pump has a built in swirl pot, sort of.
Unless the pump is a complate 100% identicle replacement for the stock pump, you pretty much have to modify the can in some way, or at the very least, you lose that second pick up.
Re: (Don R)
it should not. THe reason an inline works is because it is the pump that pressurizes the lines... the stock pump just delivers the gas to the inline.. So the intank pump does not have to do the owrk of pressurization and it takes most of the strain off of it.
Modified by drm916 at 9:31 AM 3-12-2004
| Quote, originally posted by Don R » |
| What I don't undestand is why wouldn't happen with the inline. Wouldn't the rate of suction be the same if not more. The question is does an inline run dry on a 1/8 th tank in hard corners/hard accelaration b/c of the design or is it b/c of the rate of suction? I personally have not had this experiance, but I am inclined to look into it. |
it should not. THe reason an inline works is because it is the pump that pressurizes the lines... the stock pump just delivers the gas to the inline.. So the intank pump does not have to do the owrk of pressurization and it takes most of the strain off of it.
Modified by drm916 at 9:31 AM 3-12-2004
Re: (drm916)
I'm surprised that there aren't problems running two filters inline without some sort of accumulator or isolator. I would think that you may be able to get away with it as long as the fuel filter stays in between the new inline pump and the in tank pump. Historically, many pumps don't work inline well with others without some sort of accumulator.
If the stock pump doesn't exhibit the starvation issue, then I agree there must be something about how the fuel return feeds back to the OE in tank pump.
I'm surprised that there aren't problems running two filters inline without some sort of accumulator or isolator. I would think that you may be able to get away with it as long as the fuel filter stays in between the new inline pump and the in tank pump. Historically, many pumps don't work inline well with others without some sort of accumulator.
If the stock pump doesn't exhibit the starvation issue, then I agree there must be something about how the fuel return feeds back to the OE in tank pump.
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Re: (Don R)
there has to be a quick way to easily modify something on the Walboro pump to make it work like the stock...
there has to be a quick way to easily modify something on the Walboro pump to make it work like the stock...
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