Dual 044 pump placement & wiring Q's

[abrokenframe]

Hello,

Recently picked up an 88 Carrera that has been converted to a 930 (motor, trans, suspension, brakes, slant, fuse box, gauges, etc.) and whoever did the conversion was running 2 pumps in series in front. They wired the extra pump by creating jumpers from the first pump's +/- terminals to the second.

Do you see any issues with both being upfront and wiring them up like this? I know the original 930 design used 2 relays.

I'm swapping them out for 2 044's, so now would be a good time to make any changes to the design that are necessary.

Bonus Q: Only one Check Valve on the first pump is needed, correct?

Thanks for any help!

-Ryan

[doppingcot]

Hi there,

For dual 044 pump setup, placing them upfront is fine. However, it's recommended to use two relays for proper control. Wiring directly in series can lead to uneven load distribution. Make sure to follow the original 930 design for reliability.

As for the check valve, having one on the first pump should be sufficient.

Happy swapping!

[spuggy]

You don't need two 044's, IMHO. My stock(ish) 930 ran fine on an original 911 pump - only upgraded to an 044 when I fitted the "usual upgrades" (K27, intercooler, headers etc).

Made no difference to the typical CIS fueling issues - eg they are'nt due to the pump(s). Single 044 comfortably out-performs both factory pumps.

[Tippy]

044’s draw a lot of amps. I wouldn’t trust single wiring supplying 2 pumps.

I have 2 also in series, 1 by tank and 1 in rear footwell area.

[908/930]

Also run 1 fuse for each relay.

[abrokenframe]

Originally Posted by spuggy

You don't need two 044's, IMHO. My stock(ish) 930 ran fine on an original 911 pump - only upgraded to an 044 when I fitted the "usual upgrades" (K27, intercooler, headers etc).

Made no difference to the typical CIS fueling issues - eg they are'nt due to the pump(s). Single 044 comfortably out-performs both factory pumps.

Thanks for the sound advice everyone! It all perfectly makes sense.

I've actually considered only running one 044 upfront, which would be a lot simpler and save me the hassle of rewiring for 2 pumps. Has anyone else just ran one 044?

I've read a few threads with people doing just fine with one, but splitting the workload between two 044's might be worth it.

[Bucketlist]

I also run only one 044 pump up front in my 81 SC with a highly modified 930 engine running CIS. I upgraded from the SC pump 6 years ago.

[heliolps2]

Originally Posted by abrokenframe

Thanks for the sound advice everyone! It all perfectly makes sense.

I've actually considered only running one 044 upfront, which would be a lot simpler and save me the hassle of rewiring for 2 pumps. Has anyone else just ran one 044?

I've read a few threads with people doing just fine with one, but splitting the workload between two 044's might be worth it.

I agree with everyone here, I had 400 hp 930 engine in my 76 911 with one 044 up front, I did install a rear 044 but it made my car to lean and the system pressure was to high and no way to adjust it to where I needed it to be. Remember to more fuel pressure in these CIS 930's the leaner they get the opposite of EFI. Just saying I had that car for 20 years of playing with it.

The other issue you need to address is the fuel lines which most people don't discuss. The turbo cars have bigger fuel lines. I recommend you change those to get the fuel you need. not another fuel pump.

Here's a video of my yellow beast

https://www.youtube.com/watch?v=81NfoLv8SjI

[abrokenframe]

Originally Posted by heliolps2

I agree with everyone here, I had 400 hp 930 engine in my 76 911 with one 044 up front, I did install a rear 044 but it made my car to lean and the system pressure was to high and no way to adjust it to where I needed it to be. Remember to more fuel pressure in these CIS 930's the leaner they get the opposite of EFI. Just saying I had that car for 20 years of playing with it.

The other issue you need to address is the fuel lines which most people don't discuss. The turbo cars have bigger fuel lines. I recommend you change those to get the fuel you need. not another fuel pump.

Here's a video of my yellow beast

https://www.youtube.com/watch?v=81NfoLv8SjI

Damn your car is beautiful!

Sounds like one 044 it is then. I'm replacing the majority of fuel lines, including tunnels, with -6AN while I'm in there.

[Tippy]

A single 044 is good for 650hp+ of fuel flow at EFI pressure levels. Not sure for CIS.

[abrokenframe]

Originally Posted by Tippy

A single 044 is good for 650hp+ of fuel flow at EFI pressure levels. Not sure for CIS.

Just found out my motor was built by ANDIAL in the early 2000's and has about 6k miles on it. Was told it has about 500hp... It also has ANDIAL's fuel enrichment system installed. Hope one 044 will still do!

[Tippy]

1 should do

[David]

I'm also running just one 044 pump.

[MikeD930]

For those of you running single fuel pump...can you show how you plumbed the fuel lines from the fuel pump to the fuel filter bypassing a removed 2nd fuel pump? Just curious since my 930 EFI has two fuel pumps.

[David]

^ I made new braided fuel lines from the two tunnel lines. One to the fuel filter and the other from the fuel regulator back to the tunnel return hose. It drops a couple pounds off the back of the car too. You can pull the 2nd pump relay to cut power to the pump wiring.

[gsxrken]

Cleanest way would be to have boxtergt make up a hose that replaces the 2nd fuel pump. So it runs straight from tunnel to fuel filter, instead of the stock lines that have fittings to incorporate the pump.
The two pumps can cause issues that are hard to diagnose. I had a stumble that kicked my ass for 2 years b/c my fuel pressures all checked out and ignition was fully sorted. Turns out the rear pump wasn’t contributing quite enough at higher rpm boost. There’s a fuel pressure between the pumps test that requires special fittings that Chris Carrol mentioned that finally solved it. If I was laying out my fuel system from scratch I’d use one 044 pump for sure.

[David]

Another tip: batinc.net sells metric hose ends so you can connect hoses directly to the stock tunnel fuel lines. I recommend using cloth weave lightweight hose rather than stainless since it’s much easier to make up fittings.

Also, replace the through tunnel lines if they’re more than 25 years old. Not worth the risk of failure. If you’re using braided rather than stock, this is where braided stainless would be safer.

[abrokenframe]

Appreciate all the responses guys. I went with just one pump in the front. My car has already been modified for the pumps being upfront, so install was easy. I also took the opportunity to replace the rubber fuel lines, flush the tank out, replace the accumulator & filter, clean injeoctor,s and rebuilt my FD.

I'm onto another issue now... I get a TON of fuel out of the exhaust. I don't think its the FD plunger itself because I took it apart to make sure it's moving properly. I'm going to do some pressure tests today to see if they're within spec. I'm also wondering if it could be a leaky injector or fuel exiting through the bottom of the FD into the air intake? It's a lot of fuel so hard to believe either of those would cause that. I've already hadf to do 2 oil changes from fuel flooding the engine. PITA