Our double pumper doesn't have float or siphon problems, obviously because the main body is stock. While doing some of my double pumper testing I tried to get rid of a pressure spike I had when the second pump came on, to try to eliminate the spike I drilled the siphon in my car to a larger size. It had basically no effect on the spike I'd see when the second pump came on. My fuel gauge and siphon work perfectly. My fuel light has been on for awhile. I had the car idling yesterday and it just shut off, I thought something happened to the engine! I then thought, he'll it might be out of fuel, sure enough that's what it was. Float/siphon are right on the money.

 

IF it turns out to be a float issue with the FB unit (that's where my money is), then I can't argue with the thought that the modified stock unit (e.g. Buschur Racing) is a better option. It would be just another case in a long list whereby the part that looks like a million $ doesn't perform as such. Anyway, I don't want to be premature in passing judgment, so we'll wait and see.

 

We have an update that more or less confirms my suspicions:


FYI

 

haha. I've been reading about this all morning... weird that we posted at the same time.

Lower the PUMPS in the FB setup eh I'll give that a shot tonight.

Ted,
Do you have a better solution for their JB welded wire bulkhead? Mine has cracked out...

 

Some suspected the resizing of the siphon tube (which is slight) is related to the issue they are seeing whereby the gauge gets stuck at the 1/4 tank mark. I strongly suspected this NOT to be the case, and the issue a matter of the physical assembly and placement of the FB unit.

With your having the same issue without drilling the siphon tube confirms my suspiscions as does Silk's experience.

If you have a FB unit, the sock must be very close to the bottom of the tank, and the float must have full travel (check for proper resistance). The factory manual specs I posted here tell you how to measure the float travel for proper sweep and check its resistance:

https://www.evolutionm.net/forums/9059225-post35.html


Apparently, some were a little more meticulous than the rest of us with the installation:

 

For reference our kit sits even lower than stock.....also uses a fuel approved electric bulkhead connector on the top for the secondary pump. You guys could have saved yourselves some aggravation buying......

 

Yep, we know. This is one of those situations where the trick part that looked like it was engineered for the space shuttle wasn't as well thought out as it appeared to be. Now, I've got to go back, pull the darn thing and make it right. Go figure.

 

I will say that I considered purchasing a Buschur DP, but I am the DIY type guy and like to reassure myself that I am capable of doing most anything I put my mind to. I will say, after all said and done I only saved $100 by doing it myself... If I would have dropped to loot it would have went to buschur... not nutswingging, just saying...

 

I hate.. and I mean hate to say it. But Dave's right. His setup would've been far less painful in the end.... even if I did save a grip of money.

 

wow, great info

 

Ok, I finally have an update. It took a little while for me to finally run through the tank of e85 since my car is a weekend only car and only gets miles on it if I make a run up to Georgia to a friend’s house.

Modifying the siphon tube as described by Ted B and using a Buschur Double Pump setup is confirmed working both on the saddle tank fuel usage and the full range of the fuel gauge. In my case I had high base fuel pressure with just one fuel pump running which was 59psi due to a complete wiring upgrade with 8 gauge wire to the fuel pumps. With modifying the siphon tube I was able to achieve about 45psi at idle with a vacuum reference. My fuel light didn't even come on yet at this point and I know I could have obviously gone further but filling stations are not readily available yet around here and I was coming back from Georgia. This is the only station between there and my house.

Pictures below because everyone likes picture proof...



Terrible fuel mileage I know... but I did a little data logging and minor tuning.




I completely topped the tank off and it spilled out a little.

 

I can completely confirm this post. I have DB's double pumper in my car but I also drilled the siphon tube to try to avoid using a FPR. I have a Zeitronix pressure sensor right after the fuel pumps and sure enough, even with the tube drilled, I would always see a fuel pressure spike when the second pump came on. It's still overrunning my stock FPR. I am now adding a FPR.

As far as the fuel float, mine is right on the money. When we were switching from 93 to E85 tuning, we siphoned the tank bone dry, and the thing was still running. The needle was pegged to E and it was still running. We drove 3 miles to the E85 station, and drained the rest of the tank. It had to be less than 10 oz left. The fuel float is right on the money with the DB double pumper.

-Acree

 

Yup Daves right. Hindsight I would have just gotten buschurs stock modified unit and saved my self a AAA call :-p

 

Well, thanks guys, it's a good product.

Acres, don't worry about the spike, believe me. Just leave the stock regulator.

 

I already bought the new one...

Do you really think it's not necessary?

-Acree