Quiet electric fuel pumps

[C0V3R]

OK, I have an oldish motor with a mechanical pump. On hot days or long undriven periods the fuel likes to evaporate out of the carby despite having a carb spacer.

This means that when I come to start it up again sometimes it can take a while to crank over enough fuel to start up.

I'm looking to hook up an electric pump to replace the mechanical one, but I don't really want a holley as I've heard theyre horribly noisy. Also if possible I'd like to avoid having to run return fuel lines.

Suggestions? Quiet, external, carb pressure (up to 6-12psi or so), enough fuel to supply to a 600cfm carb.

[fro]

Pierburg (sp?).

I don't know about supplying a 600cfm carb, but the one that Ive got in the rally car replaced a Holley Blue (2, in fact), and feeds 2 x 45 DCOE Webbers. Can only hear it when everything else is turned off, pumps well, and doesn't leak like the Holley's did.

I can't remember which model Pierburg I'm using, but I imagine that there will be one to suit your needs.

[takai]

My pierberg is quite quiet compared to the Bosch VL pump supplying the EFI rail. Copes quite well when filling the surge tank.

[piss98]

My Pierburg is OK noise wise - the twin VL pumps on the other hand!!

[Datto-Zed]

You don't want a Carter.....bloody noisy.

[C0V3R]

Where can you get a Pierburg from?? Havent found a site or any real specs on them.

[takai]

i got mine from bursons

[karl_2ltGC]

You don't want a Carter.....bloody noisy.

I had a little barrel type carter, just quietly buzzed away all day...

Just throw the pump under the car an you more than likely wont hear it. Rubber mounts help too.

[Datto-Zed]

Ahh well....the one I have in the zed is a shocker AND it's under the car and rubber mounted. Mind you, it's position under the car is about 1 foot behind where you sit.

[takai]

Yeah, the pierburg i can barely hear in the engine bay, and only when i first flick the car on.

[fro]

Yeah, the Pierburg in the rally car is in the spare wheel well, behind a 1.5mm aluminium firewall, and I can only just hear it with nothing else on. With the engine running, the only way to tell if its on or not is to look at the fuel pump switch...

[jmac]

If you want to run a holley (and they can often be had dirt cheap) there are a couple of options to make them quiet.

The first is probably blatantly obvious, but mount it via rubber 'mounts' (basically a chunk of rubber with threads coming out each end, one to bolt to the pump, one to the body (or brackets thereof). This makes a big difference.

The next costs a couple of bucks, and a little more work, but it's a night and day difference. Run a new fuel line (if necessary, I'd suggest a 3/8 line, and it's likely only 5/16 at the moment) and either slightly alter the existing line, or run a new 'return' line. Instead of using it with a traditional holley 'dead head' style regulator, run a return style (also called bypass) regulator.

The latter does a bunch of things. Firstly, since it bleeds off any excess fuel, back to the tank, the pump is never 'labouring' all the time (the deadhead regs just block fuel flow so that the pump then has to force against a 'closed tap' constantly) So it's quieter. It also means the fuel keeps recirculating, so it keeps the fuel and the pump particularly well cooled. The pump life will probably be quadrupled. The holley pumps have an internal relief valve. When it's pushing against a closed regulator, if the fuel pressure goes above around 10psi (12-13 on the blue from memory, 10 on the red, something like that, though the specifics aren't all that relevant) it opens. That means around 10cc of fuel will be running in circles around the pump main body, heating up to buggery.

Using a malpassi carb spec regulator (even a rising rate one, I only mention it since I've seen them very cheap - sydney speed supplies used to be the cheapest around, probably still are) will do the trick. They are generally 5/16, though I used to be able to get them with 3/8 fittings. It's not a huge worry. the trick would be to run the 3/8 supply line to the carb, and have a t piece fitting where it goes to the carb (so the line from the t piece to the carb is 3/8 as well) and run a 5/16 hose from it back to the regulator. It will then bleed off excess fuel thru the return line, and theres still 3/8 line all the way to the carb (pic on request to make it easier to visualise).

It'd take a little extra work to route/attach a return fitting to the fuel tank. The other thing to do (again probably self evident) if it's currently only 5/16 is to take out the existing sender unit/pickup from the fuel tank and separate the pickup and replace it with a diy one with 3/8 pipe.

Will that silence it? Not completely, but it would be down to a volume that was more than liveable. you'd still be able to hear it whilst stationary if there were absolutely no other cars around, amd the engine itself isn't ridiculously noisy at idle.

John McKenzie