Unbelievably noisy fuel pump!!!

Replaced fuel pump yesterday due to the old one sounding like a giant hornets nest! and suffering massive misfires under moderate acceleration.
Upon starting engine with new pump all was well, went round the block and the hornets nest is back with a vengeance! got a slight miss when accelerating but not as bad as before. 
It sounds to me like fuel starvation to the pump but I cleaned the tank and in tank filter a couple of weeks ago although it was really clean anyway.
On a plus note it starts when hot now cos the old fuel non return valve was fudged. 
Any suggestions as to what I should do/check next? 
Thanks, Ben.

If it's misfiring is it not more likely to be ignition related? What about the basics like plugs, leads, rotor arm & dizzy cap?

how full is the tank? I would try filling above half, if this helps then it will be a problem with the swirl pot

Fill it up with fuel and what fuel are you using super unleaded or normal unleaded?

I would make sure that you don't have a vibration issue with the mounting of the new pump first. A Poorly mounted pump can migrate the humming to metal really easily, and if it is next to the tank I have seen things Drum to beat the band.  So Isolate it from the metal that surrounds it, (Foam, Rubber)… Bend the mount away from items, and make sure it is Fastened tightly to the Frame….

Second I would drain the fuel and use compressed air to blow the lines clean even in to the tank.

Rotted rubber lines like to break internally and unspool so they act like valves that can open with the flow or become restrictive to it…. so what do your fuel lines look like, as the OEM lines of the 80's are rated for the Ethanol mix of most gas now-a-days E rated gas requires E rated fuel lines for proper longevity…. I know that on my 93, and 92 when I replaced the Fuel lines I noticed a world of difference in the way they ran.

IIRC the 83 was a Bottom feeder, and the Screen over the fuel line internal to the tank can get fouled, and need to be cleaned as well as come loose of the swirlpot.

Noisy Pumps are indicative of fuel starvation or restriction in the draw from the tank in my experience.

Thanks for all your replies.

I'm sure the missing/harsh hesitations are fuel related because it occurs when the pump is buzzing like crazy.

It has just over half a tank of super unleaded. 
When I used to drive it before it was parked up in the lock-up I do remember the pitch of the pump changing when it got to about quarter of a tank but not to this degree of noise.

I've made sure the pump, carrier and the flow hardline isn't touching any bodywork.

The exterior of the metal flow/return lines look very solid with only surface rust and from what I can see of the rubber lines they visually look ok but I don't know the overall condition of the internals?
Briano1234 I'm gonna do what you suggest and drain the tank and check the lines aren't restricted with compressed air, I too think it's a starvation issue. The rubber pipe from the tank that feeds the pump does look like it's deforming with the negative pressure from the pump sucking through it.
As I said when I cleaned out the tank the tank filter and swirl pot were surprisingly clean but I will inspect it all again when the fuels drained out.

Now come to think of it I had about 3 gallons of normal unleaded that I ran to begin with, with no issues and the day I put super in it these problems arose a short while later, mmm maybe whatever is in super has had some affect on the rubber fuel pipe? Is that plausible?

Well if the hose is old, it could be collapsing under the draw and when the car hesitates it returns and opens back up….rinse repeat,

Depending on the fuel we have e10, and some places e15…. I tears up old rubber bits.

You can adjust the timing to get the cars to run on normal unleaded petrol (I think it's retarded by 6 degrees) and to run on super unleaded the timing needs to advanced.
So you do need to manually set the timing to which type of petrol you use….

Cheers guys.
So when I remembered I left my siphon pump in my lock-up I thought I'd get some fuel out through the fuel pump feed pipe passively.
Please excuse my ignorance but how much flow would fuel be expected to come out of the pump feed pipe with half a tank of fuel pushing down on it? 
It doesnt seem right to me that I could urinate with more gusto! 

If it were me I would do what is called a fuel delivery check, it's hassle but that way you prove where the trouble is.

Guinness_Ben said

Cheers guys.
So when I remembered I left my siphon pump in my lock-up I thought I'd get some fuel out through the fuel pump feed pipe passively.
Please excuse my ignorance but how much flow would fuel be expected to come out of the pump feed pipe with half a tank of fuel pushing down on it? 
It doesnt seem right to me that I could urinate with more gusto! 

With the Fuel relay by-passed, you should get @ 760ml of fuel delivered in 30 seconds of running.  The amount you get is dependent on the voltage on the pump max is 760ml @ 12V  

There is a chart in the Bentley section Chapter 5 sections 11-12 describe it in detail with the chart.

I take it this is tested from the return line at the fuel distributor? As instructed in the Haynes manual?

So I took the fuel sender unit off to siphon the rest of the fuel out and look what I discovered…..

Yummy, the filter is chocker with sediment! what looked like a surprisingly clean tank when I originally looked in, is now a very gritty mess where the moving fuel has whipped it about the tank and into the swirl pot. There's a loose rusty tide mark where the old fuel was sitting and it's now everywhere! 
ggrrrrrr I can't see a way of getting this lot out without dropping the tank.
Lesson learnt, never leave fuel no matter how little is in a vehicle that's laid up for years!

Well, I've been patiently waiting for the small traces of fuel to evaporate from the tank so I can get on and clean out this crud. I'm doing this with the tank still strapped to the car (it will be removed and replaced at the end of the summer when I plan to get the underside tidied up)
Tried using a suction fed gun hooked up to the compressor and generator (no power in garage) but it was a tediously slow process, plus I didn't wanna annoy the neighbours with the noise of the genny, so ditched that idea and cautiously moved onto plan b….the portable dyson!
And it worked a treat, no flames, explosions or fireballs. After the 1st sweep with the dyson I blew out the nooks and crannies and gave it another vacuuming and then a flush thru with fuel. There's still a bit of silt on the bottom but will suck that out with the suction fed gun.
The rubber around the base of the swirl pot has broken down and fuel isn't staying tight in the swirl pot, this will probably cause a bit of starvation around corners but also means the in tank filter won't be doing it's job so I'm gonna order a Sytec filter to place between the tank n pump.
I've read about other peeps adding another fuel filter but where does it locate? Only place I can see is onto the axle beam.