Dual Fuel Pump set up: DIY 1996 e36 (alternative setup)

[Cobra1956]

Okay, Jaker you are saying you did not have the replacement pump low enough? If so I will be sure to look at that if I pull the existing pump for any inspection issues.

Thanks for the pics Matthew. I will look over what I currently have to make sure it is sound.


Still not sure if I understand how the siphon system worked and since my car is track use only was trying to figure out if you could not simply plumb in two pick ups into one pump. Will scratch my head on that for a while. Right now I just fuel after three runs unless at a bigger track like VIR then I add fuel after two sessions.Next time I have it up on the rack I will entertain a pickup in the bottom of the tank but do not plan on any drilling this season. Since this is only D/E use I might just deal with it in the end and continue fueling early since I have cans of fuel with me at all times. Not thrilled to hear about issues after the install.

[chikinhed]

This I copied from another thread of mine but might help some of you. My car is a turbo '97 M3 with 620 whp. I had been battling fuel supply issues with loss of fuel pressure in long right hand turns on the track when below a half a tank and when doing WOT pulls when below 1/3 of a tank. I tried adding a second pump in the drivers side pumping to the passenger side. It helped but didn't fix it. So last week I removed that pump, made a bracket and installed a second Walbro 400 plumbed in parallel with the passenger side Walbro 400. I positioned the pump to the back outboard side of the drivers side tank and attached the bracket to the bottom of the tank using PRC PS890 B1/2 fuel tank sealant. I've done wot pulls with just 1/8 tank and the problem long right hand corner on the track with just 1/4 tank with no loss of fuel pressure so far. Since both pumps have check valves if one looses fuel the system will still have pressure from the other pump and if one pump fails I won't be stuck. Here is a picture of the bracket and pump before install.



Sent from my GTX3582R

[bimerok]

Any info on the check valves that you used?

[Cobra1956]

I like that. I believe I could use the second pump I purchased.

Check valve look like this?





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CH, Did you eliminate the siphon hose? This would be mounted out side the splash try, correct? Any pics of it installed.


I asked these guys for some info as their product looks interesting. Instead of two pumps why not multiple pick ups. The technology to close when not in fuel is intriguing.

http://autoperformanceengineering.com/html/pickups.html

[NeilM]

Instead of two pumps why not multiple pick ups. The technology to close when not in fuel is intriguing.

http://autoperformanceengineering.com/html/pickups.html

I don't see that multiple pickups would best address the E36 situation, which is due to the saddle shaped fuel tank where gas is picked up on one side and returned to the other. Under track conditions the stock unpowered siphon pump that transfers returned gas to the pickup side is unable to keep up with demand, allowing the pickup to run dry. It's been shown for well over a decade that the dual pump setup, purchased or homebrew, fixes that problem.

The exception I could see would be that described by chickened (above), where the fuel demands of a 600+ hp engine may well call for additional measures.

Neil

[chikinhed]

I eliminated the siphon hose and the return line is split equally to both tanks. I did not use separate check valves as each pump has it's own internal check valve.

The home brew dual pump set ups either run in quasi series, which works for some but not me, and in parallel, which has been working for me so far. I will continue to test how low I can go but I thing being able to go down to the reserve, low fuel light, is enough.

Sent from my GTX3582R

[bimerok]

I asked these guys for some info as their product looks interesting. Instead of two pumps why not multiple pick ups. The technology to close when not in fuel is intriguing.

http://autoperformanceengineering.com/html/pickups.html

That's funny you brought it up. I've been looking at this for quite some time now, trying to figure out how I can connect the line to the fuel pump inlet after placing couple of them strategically. That is something I don't have a good idea for now

I don't see that multiple pickups would best address the E36 situation, which is due to the saddle shaped fuel tank where gas is picked up on one side and returned to the other. Under track conditions the stock unpowered siphon pump that transfers returned gas to the pickup side is unable to keep up with demand, allowing the pickup to run dry. It's been shown for well over a decade that the dual pump setup, purchased or homebrew, fixes that problem.

The exception I could see would be that described by chickened (above), where the fuel demands of a 600+ hp engine may well call for additional measures.

Neil

Unfortunately not. My implementation of dual pump setup still gives me starvation issues on my than LS1 and now LS2 swapped car where it starves in right handers with anywhere from 1/3 to 1/4 tank of fuel, which is about the same as it was with stock syphone system. The exact same is happening on our stock powered s52 M3 with this setup. And we know few people that experiencing the same thing and they installed the BW dual pump kit.

Sadly the two pump setup works for some, but not for the others...

[Cobra1956]

I don't think the saddle shape is anything that can't be addressed. I disagree that the siphon can't keep up being the issue. I think the issue is centrifugal force. Back to the days of swinging a pail of water around when you were a kid. Doesn't mean you are not right but I would want to think this through. In a 600 plus hp car that might be the case but for most the car runs fine in a straight line. that would indicate to me that the pump is fine....it is the ability to "find" the gas in the tank.

There is a pump that has the smaller intake. This would allow you to run duel pickups or what ever you want.

When I saw the Walbro pump shot, and if I understand it correctly, it is basically glued to the tank. So why can't we glue the tabs of the strainer to the bottom of the tank near the outside corners. Fuel lines made out of metal, bent to fit would address the saddle design and be cheaper than $28 a foot rubber hose, I think.


I have three events left and then I would volunteer my car to be the guinea pig on this.

Walbro has pumps that have different pick up sizes. I can't see why this would not work for us when it does for other types of vehicles that are addressing the same issue.




Now that the wheels are turning a bit, if you took Bimeroks original set up and you used a pickup like pictured above, you could plumb the line from the second pump directly to the pick up like this.

[bimerok]

I knew of a different pump pickups, my goal is to try reuse the oem pump instead if spending extra on another pump.

[Cobra1956]

Yeah, I am with you on that. I am actually trying to figure out how to do that also. Still looking for a reducer to make the intake work. While i always try to find a way to save a few bucks it is counter intuitive to are projects as a whole. LOL. We squawk about $100 while we are spending $5000. I have the second oem pump set up on the way. Before I start any of this I am going to test out a few things. What concerned me was that you still had issues. Either they are still starvation or the output of the pump. I don't know what the requirements are of the Cheby and so far I think the stock pump will handle the S54 I am running so my thoughts are this.
If I can reduce the sock intake to handle the reduced diameter than the oem pump is good. Dual or more pickups should solve the issue....I think. Never know what issue will arise. It appears the biggest is the proper fuel lines and rubber for gasoline submersion. I just like the idea that these pickups seal shut if empty so that should help with the saddle design. Regardless thank you for all of your posts and efforts on this matter!
Jay

[Cobra1956]

Okay, if I have this correct, there are a few possibilities to deal with to combat starvation. All of this is my own speculation.

Weak fuel pump. This could be more of an issue than most of us would think since most have a loathing of just replacing items that have not completely failed. From what I am reading here and in other threads the pumps appear to be wear item that will weaken over time.

Weak pump can cause ineffective siphon action.

Fuel sock can be torn, worn or clogged causing issues.

Stumbling over sweeping right handers could be centrifugal force related independent of whether or not the pump is working efficiently or not or any combination of the above.

The series, home brew version was an improvement but starvation was still present. The second pump system the CH installed worked very well and is similar to the use of multiple pickups in the tank.

So adding a second worn out pump(used oem I purchased) may not fix the problem.

Single pump dual pickup should work if plumbed correctly.

Thinking of either Walbro 255, Bosch 040, Aeromotive 340 for my application.

Need the proper fuel hose submersion in gasoline or what ever you are running.

Pickup or pump can be "glued" to the tank per post from CH. (Where can you buy this stuff??

Pump input need to be sized for hose or pickup size if using the Walbro pickups.


Check my work and add any thoughts please. I am about a month away from doing anything on this. Did pick up a second pump if I go that way. Then I would try to incorporate a hybrid of Bimerok and chikinhd, return line in the top of the second pump and second pump output directly to output fuel line via connector available from Walbro. This incorporate both pumps.

or

Single upgraded/new pump with multiple pickups "glued" in the tank and leave siphon hose intact. Pickups would be plumbed with metal lines and hose connectors to help deal with the unique shape of the tank. Might be able to use something like the rod on the current siphon to hold the line in place.

Only want to go at this once.
Rambling thought of this lunatic.

Thoughts?

[MatthewH]

Still no fuel starve problems for my 1994 325i after simply replacing the pump--ran it past the red low fuel light at the past couple of events.

[Cobra1956]

No argument here. Could be as simple as that. Bottom line is you gotta get in there and see what you have. I will know in about two months.

[Cobra1956]

Quiet for awhile, going to install a swirl pot. Thinking was the stock pump powers the car I just have the starvation issues when cornering and others said that the second pump in the tank did not fix the issue. Pot is on the way. WIll keep you posted.

[Maynor]

Nice. I'm very curious about your results. When I was about to buy one, I was going for an FIA rated one for a little more safety: http://atlinc.com/atl-swirl-pot-st540.html

Rubber gives in an impact versus bending/breaking/sparking depending on where you install it.

Keep us posted.

[bimerok]

Quiet for awhile, going to install a swirl pot. Thinking was the stock pump powers the car I just have the starvation issues when cornering and others said that the second pump in the tank did not fix the issue. Pot is on the way. WIll keep you posted.

That is funny how for the last 2 possible solutions we were thinking about implementing almost identical things. First it was the set up of multiple Walbro pickups in the tank. Now you're thinking about swirl pot and I'm in process of building surge tank.

I will try to give some updates on what I'm building soon in this forum

Funny thing I never saw the ATL canister that John posted and my dimensions came out almost the same.

[Cobra1956]

I picked up a pot on ebay for $60. If I understand my fuel needs correctly, any pump that can produce 150 lph should work fine. Good reading here. Did find the same numbers on another site but do not know if they are just parroting:
http://www.superstreetonline.com/how...pump-shootout/
Basic idea for those not familiar:



The low pressure pump would be the existing one in your tank.

[flink]

Seems like a lot of work. The extra pump works just fine.

[bimerok]

Seems like a lot of work. The extra pump works just fine.

We are way past that point. The extra pump in the driver's side does not work.

[flink]

Did you try plumbing it in the tee configuration?

[Cobra1956]

I actually think the swirl pot is less work. Few hoses and done. Wiring is about a push. I have a fuse box where the airbag control was on the back seat. We all seam to agree that the oem system can handle the demands. It is the g loading that seams to throw the system off. Actually both systems aren't that different. e From the info I gathered the pot will last about 1 minute of run time at wot. I have not seen anything that needs that. I also like that all of the excess fuel flows through the pot first. All of the systems I have seen include an additional filter which is nice also.

[bimerok]

Did you try plumbing it in the tee configuration?

I did not try it on my car, but talked with somebody who did and had the same experience as with transfer pump set up. No good

[aeronaut]

Subscribed!

[ITINT4U]

when are you going to post some info about your surge tank

[Cobra1956]

What are you going to use for hose? I think I am going to use the Gates Barricade F/I hose. Was going to look into ptfe but this should work and be easier to work with. Looked into making one but my skill set is not up to it.