The V8 Owners Forum -

My twin pump system isn't working out very well at all.

I fitted a new 044 pump in parallel with my original Vortec pump and one of them became increadably noisy after a few minutes.

So I removed the Vortec and fitted another 044 (two 044's) in parallel, but these are both very noisy from the first time they were powered up.

Ive tried having one or the other running , but they are both as bad as each other.
Can anyone see any issue with the way Ive plumbed it all together that would create the noise?
They both have non-return valves fitted in the ends.


thanks
Phil

The Y piece is the problem, one creates a vacuum the other has to work against. Should be two feeds from tank to run two pumps, you will find everything fine then.

Alan

1/2" is maybe a little small.

I wouldnt say the split is the problem. My tank has only a 5/8" BSP outlet, and I split this to two pumps. Never had an issue in 7 years or so like that.
It isnt my preferred option, but my tank was only ever made with one outlet...and just never got around to changing it.
It's on the to-do list, but re-welding a foam filled alloy tank has it's own issues.

What is the actual smallest inside diameter feeding the two pumps ? And how long are those hose runs prior to the pumps ?

And pumps below the level of fuel and tank outlet ?

And with 2 x 044's, you potentially have around 500lph of fuel flow, and enough for 13-1400hp...

Do you really need that much ?

But noisy is usually down to cavitation from a restricted supply to the pumps

I'd also prefer a balance of some sort prior to the rails, rather than a dedicated line from each pump to the rails.
Or simply a single line from pumps to rails, then split to each rail.

Hi,
the feed to the pumps is pretty short, maybe 12" in total. The pumps are mounted at the same height as the outlet pipe and theres plenty of fuel in the tank.

The issue I have is that if either pump is run on its own its still noisy. So the only thing I can think of is that the returned fuel is upsetting the fuel feed. I must confess Im baffled by it,
thanks
Phil

Can you take a sound clip of the noise ?


Do you have full control over actual pressure ? 8mm return is fairly small, especially for 2 x 044's

How close is the return to the fuel outlet ?

What happens if you just run the pump outlet into a container ? Does the pump sound normal ?

And a longshot...

Are the definitely genuine Bosch pumps ? Sourced from ?

What is the idea behind having two pumps this big ? I can see you are feeding each rail separately. Is this needed?

I dont know much about EFI fuelling but for that setup to run without excess resistance I would be thinking about a 1" feed or better still two separate feeds and then 1/2" from the pumps to the fuel rails. And possibly a 1/2" return line. And also maybe a balance line between the rail feeds just after the filters? Does the return line connection into the tank have a dip tube so the returning fuel enters below the fuel level in the tank so it does not create bubbles? Maybe you return line is well away from the outlet which means this may not create a problem.

I have run an 044 copy pump which was £60 and it wasnt that noisy to be honest. My mate bought the same copy pump for his drag bike and it failed within an hour of running. It had some plastic chewed up and stuck in the outlet pipe.

As Stevie says, try running it open ended into a bucket to see how loud it is. If you want to get serious then fit a pressure gauge after the pump with a valve after the gauge. You can then add resistance by closing the valve and see what pressure the gauge makes until it gets noisy while free flowing into a container.


Just thinking out loud

Perry

Thanks for the replies!

I will get the return pipe fed into a bucket and try again, that is something I wanted to try. I can adjust the pressure fine from 30 psi upwards, so I dont think Im restricting the flow from the pumps.

I will also try it with one pump running and the other pumps outlet (the one that isnt running) clamped, to see if that makes a difference. If it doesnt then the noise must just be the pumps

thanks
Phil

Are the pumps getting a full 12v?

With your electric experience it seems like saying to suck eggs, but perhaps you have overlooked the obvious and gor a poor feed or negative

Ian

Hi Ian,
I hadn't concidered that to start with, but I have checked it all and its fine. I hope to test it with the outlets running into a container over the weekend if I get some time. Too many ECUs to build!
thanks
Phil

OK, more tests and nothing I can put my finger on.
If I feed the return into a container they are the same, if I run one pump (other one off and outlet clamped) then the noise is the same, this is the same on both pumps.

Only weird thing is that the fuel pressure with one on is 37-38PSI, (one or the other) but with both on its 43PSI. So this must mean the return isnt big enough and its pressurizing.

But after going out for a little ride the fuel pressure drops to 38PSI and I start getting lean. This has happened twice now, roughly after half an hour or so of driving.
So Im going to use one pump, split it at the outlet into the 2 filters, Im sure the 044 will supply enough fuel, so it isnt an issue.
Anyone want an 044 pump, I have 2 that have ran for about 2 hours in total!!
thanks
Phil

It isnt so much a case of the return not being big enough. The regulator was adjusted for one pump.

When you suddenly double the flow, I really cant see any regulator maintaining exactly the same pressure without some adjustment

Phil, did you try insulating the pumps from the chassis? I'd run a single pump but with a 1/2" line and either a 1/2" line back or at least 3/8" and leave it at that