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I am nearing the end of my Streetport swap in my FB. My final task is to get my fuel pump installed.
I went with the Mallory Model 70 and have it setup with a return style regulator for a Dellorto 48 DHLA.
I went through a lot of the fuel pump install threads and I want to make sure my install looks reasonable.
My biggest concern is that the pump is mounted above the lowest level of the gas tank... by maybe 3-4inches at most. I know this is not ideal but I am wondering if it will still work out in terms of pump reliability/life.
Mounted with rubber isolator standoffs, should be quiet. The picture makes the pump looks horizontal.. it isn't!
That's about where my aftermarket pump is. I forget the brand but it's a high volume, low pressure vane pump. It is a couple inches above the bottom of the tank and it's been there for about 6 years and it's still going strong. Also, where did you get those rubber isolators?
Mine is also in a similar spot, was the most logical place to mount it. I believe you'll be more than fine with it's location as-is.
Many FD guys run surge tanks in their spare wheel wells, completely above the tank. I know their setups are normally worth more than our entire cars, but they don't seem to have issues defying gravity to feed their surge tanks.
I have the exact same pump mounted in the same spot. I have been running this setup for many years and it works well. That pump has adjustable pressure and I have found best results by adjusting the pressure at the pump to the maximum and using a good regulator near the carb adjusted to whatever pressure your carb needs. This gives a very stable pressure at the carbs and I am convinced it makes carb tuning easier.
The only issue I have with the Mallory pump is after awhile the brushes go out and so far I have been unable to find exact replacements so I have had to replace my pump twice for this reason (over approximately 15 years).
Coincidently I mounted mine the same way, originally with the same isolators you have, it was fairly quiet, but still audible. When I replaced my pump I changed to a smaller diameter isolator that works better, more flexible, almost silent.
The isolators are from Belmetric, they have a huge catalog of awesome hardware/misc parts. They ship quickly also. Tons of metric stuff for our FB's.
I got everything wired up and pumping. I am running an OEM filter (plastic/paper) about a foot upstream of the pump closer to where the pickup line exits the tank.
I followed your advice and first dialed up the pump regulator a few turns so that I could regulate it down with my adjustable regulator at the firewall.
Ran into an issue. It seems like this pump flows so much and my OEM return line is small enough that I cant get the adjustable regulator to do its job. Even with my adjustable (Mallory) regulator dialed all the way out I still see about 4PSI.
I think I can dial the pump regulator down a bit more.. perhaps that will work. I just dont want the two regulators fighting eachother and causing carb issues.
I will keep looking around the forums for more info on this pump setup.
That is what I was worried about. That would mean running a new hardline and also dropping the tank to have a new fitting welded on right?
I will see if I can get away with using the pump bypass to reduce the pressure (flow) to within what the oem return line can handle and hopefully still maintain fuel pressure for my streetport 12a.
You don't have to drop the tank. What I've done is step it down to 5/16" for a bit (about 1 foot or so) toward the end. Seemed to work ok as long as the outlet of the FPR has a length of 3/8" hardline for a distance under the car.
The pump bypass might help, and I have glanced at that part in the mallory sheet that comes with their FPRs.
A carter could help you, yes. I have one of the 7 to 8 psi Carters with a 5/16" send and a 1/4" return. The mallroy 4309 outlet is 3/8" as recommended and was used in anticipation for an upgraded 3/8" hardline should one be needed. But this fitting is stepped down to some 8mm line (yes I have a metric softline) that is clamped onto the original 1/4" or should I say 6mm return hardline. This setup did not flood the Nikki while used in NA mode. Only issue is the Carter is not capable of going all that high in PSI for a turbo, thus for now the plan is to only use the stock S4 wastegate spring at 5.5psi with no boost controllers at this time. I'm hoping the 2.5psi base pressure the carb needs plus the 1:1 boost reference of adding 5.5psi the turbo needs will not exceed the 7 to 8 psi rating of the carter. But it probably will. Just gotta take it easy and pay attention to what the wideband is telling me.
I have a 3/8 return line running from the regulator back to near the tank where it connects to the stock return in the tank like Jeff20b mentioned. It's been working fine for me. I do intend to add larger lines at the tank for a turbo, just haven't gotten to it yet. I used a roll of 3/8 hard line from Summit, it was fairly easy to do. If you do that, my protips (me? pro? LMAO) are just make sure you have plenty of room under the car to work with the line and cap the ends to avoid scraping up a nice little plug of oil/road grime in the end of the line. The 3/8 return hard line should definitely let you get your pressure down enough.
Awesome info guys! I did not anticipate this issue when getting everything ready for my swap.
I just looked over everything again and found I had somehow used a 3/16th brass fitting for my FPR return instead of a 1/4. It came with the parts when I bought the swap. I put a 5/16th fitting in instead and dialed down the pump bypass a bit also. I now get slightly under 4psi and this is with just a bit of spring pressure built up on the FPR adjustment.
I am crossing my fingers in terms of this working out, I wonder if the pump bypass in addition to the FPR will work out for stable pressure.
I will try this for now and can always install a hard line later if this doesn't run right.
Hope this thread helps the aftermarket fuel pump misinformed like myself.
Well it didn't work. The only way I could get the fuel pressure low enough was to almost completely back out the bypass adjuster on he fuel pump. This gave me 2.5-3PSI.
My Dellorto has the original RB installed #300 brass needle and seat. I have been searching and apparently all the brass needles require the 'low' fuel pressure. Guys that get away with higher fuel pressures most likely have a new Viton needle that can handle higher pressure.
I have decided to run a 3/8 hardline like you guys have advised. Install looks straightforward and I am pretty sure i will drop the tank and get a bulkhead fitting installed. I could always try the 3/8 return line to the original 1/4 fuel tank return fitting but I don't want to get that far and than find I still have fuel pressure issues.
Summit racing has good aluminum 3/8 hardline and i will terminate with -6AN tube nuts to hose barb fittings. Basically $60 for everything.
I couldn't find much info on return fitting installation in non GSL-SE tanks. The 12A tanks dont have a top access cover so I will be taking my tank to a tank shop and have them drill a hole and flush/clean.
I could try and run with the bypass of the pump dialed way back but I don't trust fuel pressure stability. With a proper return line the firewall mounted regulator can do its job. I don't want to be flooding this Dellorto.
Last edited by tommyeflight89; 07-15-17 at 08:56 AM.
Drained and dropped the tank and had a good shop remove the original return fitting and install a 3/8" fitting. its really just a bent 3/8" tube that goes almost to the bottom of the tank.
I took advice here and used Aluminum fuel line, and finished the ends with 37deg AN flare, tube nuts etc. I have adapters that go from -6AN to 3/* hose barb.
Installation was easier than I expected, I used the old line as a template for bending the new one, and manager to install the line in one piece from underneath the car.
Gas tank is reinstalled, can't quite get one of my straps snugged all the way up, I think because my tank has such a thick epoxy coating on the exterior it make the tank sit slightly lower. I will leave it, the bolts are fully engaged in the threads in the frame and the last thing I want is to strip out that thread trying to tighten the strap too much. One side of the strap is about 1/8" gap from where the strap should seat on the frame.
Fuel pressure is perfect now-I turned up the pump bypass almost all the way and with the FPR backed off I only see ~1PSI of pressure. Very easy to set to ~3PSI for my carb.
For future reference this is the way to go.. stock return line on a FB (non GSL-SE) is just too small to support a setup like this. You could run a deadhead regulator but that won't be worth the pump problems you will have in the future.
Last edited by tommyeflight89; 07-26-17 at 04:40 AM.
07-04-17, 07:58 PM
