Low pressure lift fuel pump...

[JoeMag]

What low pressure external to tank lift fuel pumps have folks used? I setup my new cell with only an 044 pump on top and get an occasional (few times a race), low fuel pressure blip (below 38psi, set at 45psi). I have aim dash so lots of data (blip very short, like 0.1 sec or so). Originally had the big 993 fuel cell with same pumps low on front of tank and had rock solid (flat line) fuel pressure. New cell has two hydromats with return hose in tank extending down to just above top of one of the mats, assuming it's not a scavenge issue and do get the blip even when pretty full.

[Evan Fullerton]

I haven’t used it yet but I bought the Radium built in surge tank setup for my Cell. It uses an identical lift pump to feed the internal surge tank as the pressure pump to the engine.

The surge tank has check valves in it to allow fuel to flow into it when the tank level is high enough so I’m thinking of wiring the lift pump into the surge tank only as a low fuel reserve.

[safe]

I use a stock tank and an external surge tank. I fill/circulate the surge tank with a high pressure walbro pump, I had it so I used it. Then I have a 044 to feed the engine.
Probably overkill or sub optimal in some way...

[stownsen914]

Fair enough to be concerned about low fuel pressure, but .1 sec might seem like more of something to keep an eye on, than requiring a change.

When you say lift pump, do you mean just a second pump inline? Or adding a swirl pot with a second pump feeding it? I didn't think a second inline pump was a common race setup.

One thing - I see you have the pump mounted on the top of the cell. I've understood it's generally recommended to mount the pump as low as possible to minimize the "head" it has to work against.

[Alex12]

Originally Posted by JoeMag

What low pressure external to tank lift fuel pumps have folks used? I setup my new cell with only an 044 pump on top and get an occasional (few times a race), low fuel pressure blip (below 38psi, set at 45psi). I have aim dash so lots of data (blip very short, like 0.1 sec or so). Originally had the big 993 fuel cell with same pumps low on front of tank and had rock solid (flat line) fuel pressure. New cell has two hydromats with return hose in tank extending down to just above top of one of the mats, assuming it's not a scavenge issue and do get the blip even when pretty full.

Not to sure but i think i have one of these.

[JoeMag]

When I mean lift pump I mean a pump between the pickup and the pump shown in pic. Basically spliced in on that AN line. When I designed the cell and had it built they asked if I wanted a lift pump in the cell and I thought it would not be needed since it's only about 12" high. You're right about two external pumps not real common setup (though my 930 had a low press pump off the bottom of tank and high press pump in back of car).

Yea, I know 0.1 sec is not long, however, seeing these warning lights flicker during a race just gives me something else to think about what's going wrong. Do not want to lower limit further (38 psi being already too low at setting of 45psi) as I'll miss a real problem.

Guess I'll just get pump and splice it in.

[Walt Fricke]

Why not use a surge tank? You could use about any pump to fill the surge tank. As far as the height of the pump from the tank bottom, I can't see that as an issue with the Holley reds I have used on top of the tank. Mounting the pump low works only if the exit from the tank is low, doesn't it? Like the stock tank? You have to lift the fuel up over the top with your setup (which is basically common, as most if not all fuel cells have the fittings on top), and I can't see you getting much of a siphon effect by then mounting the pump down low. But I could be wrong on that. Nonetheless, most pumps should have the ability to lift a foot or so.

Are you feeding a 3.8 monster? Have you looked at flow in lph or gph vs pressure? I don't know what those specs are for the 044, but lots of them are used as the only pump.

I agree that having the blip at, say the half tank level, would tend to make one thing it isn't a fuel sloshing/pickup issue. I've used two pickups, but had a separate pump for each, Teed together for their output. Sucker would run until zero fuel - no warning from cutting out in hard corners. Never a hiccup.