Electric Fuel Pump w/ SU's

[MrFancypants]

I read a thread indicating that the mech fuel pump on the L-series can leak fuel into the crankcase. Fuel in the oil is bad. I noticed a lot of fuel in my oil, so naturally I suspect the mech fuel pump.

 

I'd like to rip it out and replace it with an electric fuel pump. Since Im eventually going to replace the motor entirely and go EFI, I want to use something that will be useful in the future.

 

The most highly recommended LP electric fuel pump Ive seen is this one: http://www.racetep.com/webfuelspark.html#webfuel

http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRT%2DP4070&N=700+115&autoview=sku

 

Now, is this the right pressure/flow for the dual round top SU's to completely replace the mech pump? Will this be useful for a surge tank application down the road as the low pressure high flow pump feeding a high pressure EFI pump?

 

 

 

- Greg -

[e_racer1999]

that's the right pressure (i would say 6 psi max), but most of that flow is going to be coming back in the return lines (to my knowledge).

 

i would say in the mean time get an RX7 pump.

 

my 0.02

[Zmanco]

You should be able to run the carter directly to your SUs without a regulator. But if your needle and seats are worn, it might be a little too much for them. Also, it's not as quiet as the mechanical or other lower performance electrics. I tried one when I thought I had a fuel delivery problem and found it a bit loud for my tastes and since the problem was something else, went back to the original pump. I still have it - only has a few hours running time on it. PM me it if you're interested.

 

When I converted to Megasquirt I did the same thing you suggested. I added a surge tank and a walbro for the high pressure side and have been very happy with it.

[MrFancypants]

but most of that flow is going to be coming back in the return lines (to my knowledge).

 

What GPH am I looking for on a L28 with SU's? Here are a couple others with less flow:

 

30 GPH @ 4psi: http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRT%2DP60504&N=700+115&autoview=sku

 

30 GPH @ 6 psi: http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRT%2DP60430&N=700+115&autoview=sku

 

Im not too worried about a lot of return fuel, especially if I will be using this to drive a surge tank down the road.

 

 

 

- Greg -

[MrFancypants]

I tried one when I thought I had a fuel delivery problem and found it a bit loud for my tastes and since the problem was something else, went back to the original pump. I still have it - only has a few hours running time on it. PM me it if you're interested.

 

When I converted to Megasquirt I did the same thing you suggested. I added a surge tank and a walbro for the high pressure side and have been very happy with it.

 

So youre using the stock 12V pump to drive your surge tank? Were you able to run the carb setup with just the stock 12V or is the mech pump necessary?

 

 

 

- Greg -

[Zmanco]

What GPH am I looking for on a L28 with SU's?

I don't think you're going to have any issues with a 30 gph pump. Look at it this way: On my last track day with triple webers I averaged right around 10 mpg. If you drove for an hour at 100 mph at 10 mpg, you'd use 10 gallons per hour. I think it's unlikely that a stock L28 is going to use more fuel than a 30 gph pump can provide. (I realize the pump is rated at "no load", but it's still 3 times my example.) Others jump in if you think it needs to be bigger.

[Zmanco]

So youre using the stock 12V pump to drive your surge tank? Were you able to run the carb setup with just the stock 12V or is the mech pump necessary?

Yes, I'm using the stock pump to fill the surge tank.

 

Before converting to megasquirt I ran the SUs and triple webers with a moderate cam off the stock fuel pump. In all fairness, it's not truly stock - it looks like an inexpensive generic rotary from Autozone or equivalent.

[e_racer1999]

What GPH am I looking for on a L28 with SU's? Here are a couple others with less flow:

 

30 GPH @ 4psi: http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRT%2DP60504&N=700+115&autoview=sku

 

30 GPH @ 6 psi: http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRT%2DP60430&N=700+115&autoview=sku

 

Im not too worried about a lot of return fuel, especially if I will be using this to drive a surge tank down the road.

 

 

 

- Greg -

 

as was just mentioned, 30 GPH should be sufficient and not overkill. but i'm mostly talking out of my @$$ on flow rates.

[Goose52]

I ran that same Carter pump from the late '70s until 2006. Before '82, it fed a 331ci SBC - after '82 it fed an L-28 with SUs. No problems with pressure or flow rate with either engine. HOWEVER, like was mentioned above, this is a noisy pump; even after pressurizing the lines, I could still hear it running whenever idling.

 

I pulled the Carter out in 2006 as part of a mechanical refresh (it was still running fine but I just wanted to change it out due to it's age). I'm now running a Mallory 70LP (low pressure) - 4psi, 70gph. This is a very quiet pump and I'm pleased with it so far. Some have said the Mallorys don't last as long as other pumps - I guess only time will tell ...

 

Goose