Bosch 044 Fuel Pumps, Filters & rubber lines heating up/getting hot

[stradlater]

I've got my 2x 044 Bosch Fuel pumps. With 2 standard Commodore fuel filters after them. The in line is -8 from the surge tank to the pump. Then -6 out, into a Y piece that feed -8 to the motor.

I'm running 40 PSI fuel pressure, nothing terribly surprising there.

But the pumps (and one of them is BRAND new) start to warm up and make a bit of noise fairly quickly. The surge tank also gets warm to touch as do the rubber lines.

Is this just a case of the fuel getting warm in the engine bay area, or is there something else more serious?

The main fuel tank doesn't get warm at all, it remains cool.

Thoughts? I dont' mind if I kill another pump and have to replace it - not that I really want to, but it's not the end of the world. What I really want is stable tuning. Clearly the hotter the fuel gets, the crappier the tune gets.

[MRMOPARMAN]

that's a fair bit of fuel. id say its a combination of engine bay heat, and heat from the pumps pumping causing the fuel temps.

fix would be to run a fuel cooler, convert to returnless system, reroute the lines to a cooler spot (say further away from exhaust etc) or try turning a pump off at low load (if your ecu allows for it) or a combination.

[Omegaman]

i know nothing, but....if the pumps are heating up, also the surge tank. Can't we assume that neither is getting enough fuel?
Fuel, cools the pumps and stops them from being noisy!!
Fuel pressure maybe too high at 40psi.
Is there a lift pump in there somewhere?
just a thought....

[mx83toy]

lift pump helps alot!!! even just a little facet... (we have one on a 700hp ATW twin bosch setup) fuel cooling is something were having to look into now as we are getting similar results dont know enough about it yet to give advise besides look into cooling and best of luck...

[Omegaman]

A lift pump to me is vital in a surge tank set up.
Stadlater may have an in tank pump, as he does not mention the car or engine type.
But even a 5-6psi lift pump wont help 2 high pressure flowing pumps, is my guess.
But just like you mx, i'm only new at this on my engine.

[dnegative]

Blowing the relief in the fuel rail will warm the fuel as will engine bay temps, try dumping the return to tank.
Pumps are going to get warm when in use.


How hot are we talking here?

[oldcorollas]

can measure pressure before the commodore filter?
40psi straight?or reduced with manifold pressure?
can you measure the temp?

noise is either workin hard, or cavitating..

is surge tank full?
lift pump (if one) not keeping up? or it's aeriting the feul so the 044's suck frothy fuel?

err, is pump voltage dropping as wires heat up?

[dnegative]

noise is either workin hard, or cavitating..

Should be working hard all the time maintaining 40psi rail pressure, they are a fixed positive displacement, fixed RPM vane pump.
They are noisy by design I think, I imagine two of them would make a decent sound buzzing away.

[DX20VT]

I would say the fuel is heating up in the rail in the engine bay and bringing the heat back to the surge tank,
especially worse as with both pumps you will have quite a lot of return flow.

On my race car it only has a 22L fuel tank and after a 10 min race the fuel itself left in the tank is quite hot.
The tank is aluminuim and is quite hot to the touch.

For some of the race cars we built we had fuel coolers on them to stop it.

On some of the endurance cars we had they had separate main and surge tanks,
so the constant flow of cold fuel from the main tank to the surge tank help the fuel at an acceptable level,
depending on the flow rates you have on your lift pumps to how much the engine uses.
Too much flow and you pump too much hot fuel into the main tank and it will eventually heat up too.

[dnegative]

A Bosch 044 will flow 240L/h @ 3bar. With two pumps your putting 8L/min through your pressure regulator.
That's a heap of fuel and its going to get hot going through the relief.


Dump the return back to tank and see how it goes.
Assuming its a decent sized tank with some surface area under the car it should radiate a decent amount of heat. Pretty sure there are calculations for hydraulic reservoirs that will translate.

[DX20VT]

Dump the return back to tank and see how it goes.
Assuming its a decent sized tank with some surface area under the car it should radiate a decent amount of heat. Pretty sure there are calculations for hydraulic reservoirs that will translate.

Got to be careful though as the two 044 pumps may drain the surge tank quicker than the lift pumps can keep it topped up,
so the surge tank may run out of fuel and the pumps will run dry.
( presuming the surge is feed by pumps not gravity fed, as gravity feed can give an awesome flow if done right)

[dnegative]

Got to be careful though as the two 044 pumps may drain the surge tank quicker than the lift pumps can keep it topped up)

If that is the case then the OP effectively has a almost closed loop fuel system with the lift pump effectively acting as a charge pump for whats used~
Going to be hard to keep the temps low if that's the situation.

[DX20VT]

That is how 99% of the surge tank setups I have seen work,

The main pump draws from the surge tank, and returns to the surge tank,

the lift pump pumps from the main tank to the surge tank,
and there is an overflow from the top of the surge tank back to the main tank.

That way the lift pump only needs to flow the amount that the engine uses,
not the full flow that the 044 will supply which is what you need if the return is to the main tank.

I would say he has it returning to the surge tank as usual as he stated the surge tank gets warm but the main tank does not.

[dnegative]

The lift pump needs to be big (ideally) enough to supply more than 100% of the fuel load for the engine otherwise you run the risk of the pump sucking air if it cant keep up with what the engine is consuming. Ideally you would want the surge tank always be in or close to overflow.


I think the issue lies in the size of the surge tank and the fact it cant cope with the heated fuel from the rail return.

[DX20VT]

enough to supply more than 100% of the fuel load for the engine .

by load do you mean the fuel that is going through the injectors,
or the fuel that is going through the rail?