Fuel pump problem... HALP!!

[Joe]

Hi guys,

I've posted this on PWRX too and have had some great ideas come out of it, but am looking for an expanded opinion.

Basically my Bosch 044 is super noisy.. I was considering swapping it for a Walbro but I kept it because it was the most suitable pump for my setup.

From the info I can find on the net, some people say they’re noisy and others say they’re supposed to be quiet.. the ones who say they’re supposed to be quiet, say they get noisy when there is a blockage or a restriction.

So basically:

- When I got the pump, it was fine. It progressively got louder and louder as time went on.

- There is no restriction I can see apart from the strainer being a bit dirty, but nothing out of the ordinary for an 8 year old fuel sock (I’ve seen worse).

- The strainer is threaded and is screwed straight into a speedflow fitting on the bottom of the pump. Maybe this is causing a restriction because it sits so close to the fuel pump inlet?

- The pump is fairly new (less than 10 months)

- The pump isn’t making a smooth buzzing noise when its running, it sounds more like its “jumping” or "stuttering" every second or so (not spaced perfectly apart though), which could be cavitation.

- The pump is hard-wired to 12 volts all the time, so its flat out even at idle.

- It's insulated with fuel-proof rubber, so its not the vibration transferring through the cradle and tank which is causing the noise.

- The pump is louder when the weather is hot, which I'm told is normal for a Bosch 044.

- When the pump primes, its quiet for the first 1-2 second of priming, then the remaining second or so, it gets loud.. so basically it only gets loud when the lines are pressurised (I don't have a check valve).

Any ideas?

I've been told it could be the following..

- Faulty FPR causing excessive back pressure on the pump
- Blockage in the line (unlikely)
- Outlet hose to hard line on cradle could be collapsing, as its a braided rubber hose and has been in the tank for a couple of years.
- Some 044's had a check valve INSIDE the outlet (not the one that screws onto the outlet on many of the Bosch pumps, but another one inside) that could be restricting flow.

Any real world experience or solutions would be great.. also if anyone has a spare 044 they'd like to lend me for an hour or so, I'll be pulling the cradle out, swapping the pumps over and running it for a few mins to see if its just the pump causing the problem.

[TJ]

I thought you already stuck a walbro in this ?

[Brett_J]

Disconnect fuel line off fuel rail, try and get a decent sized bucket and turn on ignition so pump runs, see when it "stutters" if there is a change in flow.You might have just got a dud pump, Of all the Bosch pumps Ive used they have been slightly noisy, but not like what your describing.
Go for anything else but a Walbro dude if your gonna change :)

[Tre-Cool]

I have twin 044's in my vy ute, have single 044's on my dads ute & stato and they are all loud. I have never seen/heard of a quite 044 pump.

When they get hot, they get even louder. Price you pay for having a good pump i guess.

All ours are external (though i dont think they make an internal 044?)

[Brett_J]

Bosch 040 is the intank version of 044 I believe

[jaybee]

as far as im aware, there are 044 intank and external pumps

what fpr are you running?

- Outlet hose to hard line on cradle could be collapsing, as its a braided rubber hose and has been in the tank for a couple of years.

is this just braided rubber or braided teflon hose? if its just rubber, by now the hose would have diminished and is probably leaking, could be a small factor?

[Joe]

Jaybee: its braided rubber, so thats where I'm going to look first.

Brett, great idea.. I'll try that bucket trick. Only problem is, I can't run pump for more than 2 seconds when engine isn't running, have to change the settings on the MoTeC to allow that.

I'm trying to source another Subaru with an 044 fitted, with an owner willing to let me swap them out for 10 mins.. if my pump still makes noise in their car, its the pump or something attached to it. If not, then its further up the line.

[Lump]

maybe take the pump out & run it in a drum of fuel or similar & see how it sounds

[Saf]

+1 NWR.

Yank it out, check its flow based on no head pressure.


When they get hot, they get even louder. Price you pay for having a good pump i guess.

Price you pay for the shit fuel we have here. As the density of fuel goes down with pressurising (pressure = heat), and running thru a hot rail, and back into the tank known as a circulating system, the fuel does make the pumps noisier.

I also free mount pumps (external pumps mounted outside), meaning they float. P-clamp on the inlet line before the pump, and another on the outlet, and none around the pump.

[joshg123]

Id put a fuel pressure gauge on it first and check your rail pressure to see what its pumping against. My 044 did that stuttering when i had my rail pressure at like 70psi when i first built the car, haha whoops! Backed off the FPR and she came back to normal.

Was also super noisy when i was running out of fuel on the dyno.

[Lump]

Was also super noisy when i was running out of fuel on the dyno.
that would be it cavitating lol

[Saf]

I think Joe has a fuel pressure gauge from memory ... but now the more i think of it, maybe another subi im thinking of.

Joe ?

Anytime a modificcation is done on the fuel syystem away from standard, the two things rule of thumb that should be done is a FP Gauge, and a fire extinguisher.

[joshg123]

that would be it cavitating lol

Yerp, had no fuel gauge in the dash, just a tacho and water temp. Scratching the heads for a while when the tuned seemed to be leaning out on the dyno when more fuel was added. Couldnt hear pump over motor and big fan

[Lump]

thats a shame, that car had a fuel gauge in it when i sold it to you :P

[Brett_J]

The reason I suggested disconnecting it from fuel rail and testing it is because thats a good 80% of the fuel system, if its still doing all the same things you can rule out fuel rail/injectors and then work your way back to pump, if its not then you can start from the fuel rail onwards.

Also put a multimeter on the pump to make sure its getting its 13-14v constantly :)

[Joe]

I was going to trouble shoot the pump by dropping the cradle into another car.. if its still making weird noises, then its the pump.

If not, its everything past the pump cradle (hard lines, reg, rails, etc).

[ovaxitd]

sounds identiacal to mine in my jzx intank with a filter on bottom.. i still have on factory wiring so it stitches over.... when it gets hot it gets nioisy.... dw about it joe... i checked my fuel pressure and nothing changed with the noise going high/low

[Lump]

is the filter/sock provided with the pump? because if its providing ANY more restriction than it should be, that will cause cavitation/noise.
i wouldnt be surprised if the noise your getting is normal tho.

[Joe]

No, I used the stock one.. the plastic elbow was threaded and screwed into a speedflow fitting.

[Lump]

well any more restriction at all on the intake of a pump (than its designed for) can/will cause cavitation.
that goes for extra, pipe, elbows, different socks (especially used ones) etc
cheers

[mys1]

As long as there is constant fuel pressure and good flow, then id put it down to being a noisy pump! Always pays to check these things, as if there is soemthing wrong, i think someone once told me that fuel is kinda a big deal when it comes to tuneing big hp on stock injectors.....

[Saf]

big deal when it comes to tuneing big hp on stock injectors.....

Dude you make it sound like such a big deal !!!!. Very over-rated !

[heller44]

How large is the sock / strainer that you have mounted on the intake? I used a falcon strainer on a turned down metric / an fitting on my 044 intank and it seems to be alright with that..

[[RX2]]

braided rubber lines deteriate from using unleaded, your ment to run teflon lined braided hose if using unleaded

all my o44's that i can remember have been noisy

has it ever ran out of fuel/ or starved of fuel ? that usually hurts the pumps & makes them louder before they enf up failing completley

[ovaxitd]

http://www.mazdarotaryparts.com/bfc-fs001a-bosch-044-filter-sock--adaptorb-1070-p.asp

^ that the sock i got for my 044... works mint and had no dramas..

cheaper than any other filter available in australia.