Date: Sat, 16 Dec 2006 12:47:20 -0500
Reply-To: Greg Potts <greg@POTTSFAMILY.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Greg Potts <greg@POTTSFAMILY.CA>
Subject: Re: Fuel pump buzzing
In-Reply-To: <0E59B3A0-1263-4750-9CDD-3DEE3A9A9FFF@SBCGLOBAL.NET>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Hi Geza,
The FI system in the vanagon requires only a portion of the fuel the
pump can supply. The remainder is put back in the tank through the
outlet in the Fuel Pressure Regulator. An impaired pump can often
remain able to keep up with the engine even though well below full
capability.
It would indeed be bad practice to replace the pump without checking
to ensure it has a good fuel supply. Checking the fuel filter and
tank outlet are definitely worthwhile. Dad has replaced two vanagon
tanks in the past couple of years.
Happy Trails,
Greg Potts
1973/74/75/77/79 Westfakia "Bob the Tomato"
www.pottsfamily.ca/westfakia
www.busesofthecorn.com
On 16-Dec-06, at 12:32 PM, Geza Polony wrote:
> Thanks Greg. This is the kind of explanation I was looking for.
>
> On the other hand, if the car is getting enough fuel to run, how
> come the bearings aren't lubricated in the FP? It would seem to me
> that it's either dry and the car wouldn't run, or "wet" with fuel
> and the bearings would be lubricated and cooled.
>
> I probably will replace the pump and regulator. But I hate doing
> this without completely understanding the nature of the problem.
>
> I'm also thinking that if this is true, the place to start
> replacing is the fuel tank, not the pump. Low flow would eventually
> just burn out the new pump, no?
>
> thanks again,
>
>
> Geza
>
>
> On Dec 16, 2006, at 8:55 AM, Greg Potts wrote:
>
>> Hi Geza,
>>
>> Fuel starvation makes the pump heat up, as it is not being cooled
>> by the fuel flowing through it. At the same time it is also being
>> asked to work harder to pull fuel. Ever hold the shaft of an
>> electric motor still while applying power to it? (drill or power
>> saw, for instance) Electric motors hate that, and they will make
>> noise to tell you about it. That's what your fuel pump is doing.
>>
>> The heat and extra stress will soon wear out the bearings in the
>> pump, and thereafter the pump will be loud regardless of whether
>> the fuel is flowing freely to it.
>>
>> If you resolve a starvation condition early enough your pump
>> should return to silent operation. If it doesn't, then you should
>> consider carrying a spare before venturing on any long trips away
>> from mechanical assistance. It might keep going ok for years, or
>> perhaps not. If it were my bus I'd change it out and carry the
>> noisy unit as a spare in case someone else's failed. YMMV.
>>
>> Happy Trails,
>>
>> Greg Potts
>> 1973/74/75/77/79 Westfakia "Bob the Tomato"
>> www.pottsfamily.ca/westfakia
>> www.busesofthecorn.com
>>
>>
>>
>> On 16-Dec-06, at 11:26 AM, Geza Polony wrote:
>>
>>> What I'm still not getting is how you can replace a fuel pump and
>>> still have
>>> it make the buzzing sound. The consensus in the archives seems to
>>> be that
>>> there are two causes for FP buzz syndrome: fuel starvation,
>>> either because
>>> of a clogged filter or because of a clogged fuel line before the
>>> filter, or
>>> bad pump bearings caused by the fuel starvation. How could "fuel
>>> starvation"
>>> make the same sound as a bad bearing? And how can you tell?
>>
>
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