Buzzing fuel pump

[chuck 0]

Hi,

Since I bought my '90 1.8 16V, the fuel pump buzzes when the engine is hot. Simple, I thought, so i replaced the pump (they're not cheap!!). But the same thing still happens.

Symptoms: When less than half a tank of fuel, it can buzz at any time except cold. When more than half a tank of fuel, it only buzzes in thick traffic when temp goes above 100. Then the hotter it gets, the more it buzzes, till eventually the car starts jumping about the street :oops: and may eventually stop. Starts easily again, but same thing happens.

Buzzing sounds like an electric saw cutting wood. Really loud too, can hear it bouncing off neighbouring car.

 

The really annoying thing is that keep the tank full, and the engine cool and it will never be heard.

 

I've had the C a month now and no problem has been simple.

 

Any advice

Thanks

[joby 0]

Check the mountain brackets there will be rubber mounts they may have gone brittle and sometimes the pump resonates through the car ? Just a thought !

[chuck 0]

Will have a look.

Had another thought, I read somewhere recently that I should be using 4 star or super unleaded, but I'm only using premium. Would this affect it, as it only happens when the engine is warm.

[Joe M 0]

Mine makes the buzzing as well, has done for the last 2 years since I got it. The jumping around the street could be unrelated, I would get the hall sender in the distributor checked.

[chuck 0]

Have checked the mounts. All seems fine. Distributor was just checked at a service a few weeks ago, so I'm assuming that should be OK. So I went into VW and asked. They say that the fuel lift pump is almost certainly at fault. If this isn't working properly, it will cause the main pump to strain and make a horrible noise and will eventually result in the erratic behaviour of the engine. That makes sense as a mate who had the same problem replaced both pumps and it was fixed. I took the cheaper route and replaced only the one that was making the noise. :? Next stop Euro parts!!

[Pau1 0]

Hi,

 

Sounds like the fuel LIFT pump has gone. Mine did this last year. I

replaced the Fuel Pump and it still did the same, but if you replace the fuel

LIFT pump it should stop.

 

Paul

[Pau1 0]

Oh , and i forgot to say that you should only be running it on OPTIMAX

fuel. The VW needs 98 RON petrol and normal Super only gives you 97.

I know Optimax is more expensive but you'll get better MPG out of it.

 

Paul

[Banana Man 0]

Yeah paul sounds like he's got it down to a 'T' my which is basically the same did this 3 years ago I replaced the main pump but that didn't stop the buzzing so I then replaced the lift pump and that cured it, its probably buzzing because it will have to be working alot harder to get the fuel up from the tank if it is the lift pump that has failed. I run my G60 on normal super with a wynns octane booster at each fill up, seems to do the trick it feels so much more responsive than running it on normal unleaded. I didnt really notice any difference when I tried optimax to tell the truth so dont bother with it anymore!!

[Joe M 0]

So what other symptoms are there when the lift pump is gone, I get the buzzing but it doesnt bother me and the engine seems to be runnig ok.

Also, how much is a new one and are they easy to replace?

[chuck 0]

The part is £20 from VW. Only thing is they don't stock it and have to bring it in from Germany. Could take about 10 days to deliver.

Looking at the Haynes manual (for scirocco)- its fairly easy to replace. Its under the black cover under the boot carpet.

Buzzing is intermittent (worse the less fuel is in tank), and its only if its been buzzing for about 5-10 mins that it affects the engine. And the buzzing is really harsh - my skyrockets fuel pump made noise, but this is a horrible grinding type noise. Hopefully this will fix it.

[chuck 0]

Hi all,

Just an update on the pump. The pump finally arrived, but didn't want to fit. So I took it back to VW who then found out that there was a modification. Pump changed - so did the filter.

So info on this - if replacing an early 16V pump (pre '92) you need pump 357 906 092C and filter 357 906 098 (though they might not tell you about the filter - causing you to wait a few more days :x )

Oh and it fixed the problem - thanks.

And while I'm at it with info; when I bought the C i noticed that it got very hot befor fan came on - up to 110 degC!! this is much hotter than any other car I have driven. Iwrote to the Yahoo group and found that tis was normal and got the impression that it makes many C owners paranoid - sometimes to the extent that they would turn on heater to max and open windows!! So I found from this site a part number for a lower temp thermoswitch. Since fitting, the temp sits at 90 as per norm and only rises to about 97deg before fan comes on. Perfect, now I can drive through town without the just-in-case attitude of having the oil temp showing all the time.

Part number is 251 959 481K (or 701 959 841) with temp ranges of 87-76'C/93-82'C. and I have checked - this does not cause the fan to be on continuously - it only comes on when in traffic.