Date:         Sat, 16 Dec 2006 16:24:11 -0500
Reply-To:     Geza Polony <gezapolony@SBCGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Geza Polony <gezapolony@SBCGLOBAL.NET>
Subject:      Re: Fuel pump buzzing

I guess the rule, then, is start at the front, work towards the back.

Thanks for the explanation(s).

Geza


On Sat, 16 Dec 2006 12:47:20 -0500, Greg Potts <greg@POTTSFAMILY.CA> wrote:

>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?
>>>
>>