5 seconds of cranking to start

[Grant Lenahan]

When you turn the key to "run" in my 986 the fuel pump hums.

Grant

On Oct 8, 2007, at 10:14 PM, Cody Forbes wrote:

> To be perfectly honest I'm not up enough on the other older models, 
> but I
> know for certain that 5000's, turbo and otherwise, do not run the fuel 
> pump
> prior to cranking. Now you must understand that these cars are old and 
> many
> have passed though many hands. Not alot of people can really properly 
> fix
> CIS systems, 75% just bandaid problems by doing stuff like hotwiring 
> the
> fuel pump. On a 5kT it's as easy as installing a fuse in the fuel pump 
> relay
> and voila, pump runs with key on.
>
> I'm familiar with CIS on 5k's and Porsches, and on certain others, but 
> my
> specialty in my day job is Porsche's. Even CIS Porsches do not run the 
> pump
> unless the engine is either being cranked or running, but they have 
> much
> easier methods to by-pass this. On the early and middle generation 
> Porsche
> systems had a switch that shut the fuel pump off when the airflow 
> plate was
> resting at the bottom. When air starts flowing the plate lifts and the 
> pump
> starts. Funny part is there's a dedicated 2-pin wire connector that you
> simply un-plug and the pump runs. I've seen DOZENS of them come to me
> un-plugged, only for me to diagnose a simple fuel pressure leakdown in 
> the
> system solves the REAL problem and allows the pump to be run as 
> factory.
>
> I doubt your EFI cars, especially the newer ones, run the pump with 
> the key
> on engine off, at least as they left the factory. I would say they run 
> for a
> second or two when you first turn the key on to prime the system, but 
> they
> shut off after that. Anything beyond that is a major safety concern.
>
>
> -Cody Forbes
> http://www.5000tq.com
> '87 5ktq - Fast.
> '86 5ktqCD
> '86 5k
> '86 5k
>
>
> Grant Lenahan wrote:
>> Are you sure? It was true on my 84 4kq, 91 90q, 95 a6q, 00 S4 and 02
>> S6.
>> Was the 5kq THAT different?
>>
>> Grant
>> On Oct 8, 2007, at 12:08 PM, cody at 5000tq.com wrote:
>>
>>> Grant that would not work on a 5ktq. They only run the fuel pump when
>>> the engine is turning, whether by the starter or by running of
>>> course. Jeff, this is not 'normal' for your car, but not uncommon at 
>>> all
>>> among CIS fuled cars. Grant's suggestion of the leaking check valve
>>> is a likely culprit, as are the fuel pressure accumulator, o-ring on
>>> the pressure by-pass piston in the fuel distributor, warm-up
>>> regulator/differential pressure regulator, and leaking injectors.
>>>
>>> Diagnosing this issue without a CIS pressure gauge set can be tricky.
>>> Start by watching carefully for a puff of white smoke when starting.
>>> This would hint at leaky injectors. Next you could install a fuse in
>>> the top of the fuel pump relay, which would put the car in diagnostic
>>> mode and make the fuel pump run any time the ignition is on. Now
>>> Grant's test is valid - when it's cold like it normally would be you
>>> turn the key on and just let the pump run for a few seconds, then try
>>> to start. If it starts right away, or at least faster then usual,
>>> then we have determined that you have a problem with fuel pressure
>>>  leakage. From there it is hard to diagnose without a gauge set, so
>>> you may want to either purchase one or visit a friendy shop that is
>>> properly equipped. You *could* try removing the fuel injectors
>>> (engine not running) and look for leakage, but from there it's all
>>> guesses without a gauge set.
>>>
>>> -Cody Forbes
>>> http://www.5000tq.com
>>>
>>>
>>>
>>> Quoting Grant Lenahan <glenahan at vfemail.net>:
>>>
>>>> Uncommon.  But the real question is "did something change?"
>>>>
>>>> I have foudn that long cranking can be a sign of a weak fuel pump or
>>>> leaking check valve. On older cars, try this:
>>>>
>>>> 1. turn key to run, listen for fuel pump.
>>>> 2. after 3-5 sec, start car
>>>>
>>>> Did it catch faster?
>>>>
>>>> Grant
>>>> On Oct 7, 2007, at 10:00 PM, JeffreyZentner at aol.com wrote:
>>>>
>>>>> Hi All
>>>>> I have a question I have a 88 5KTQ and when I start it when it is
>>>>> cold
>>>>> it
>>>>> takes about 5 seconds of cranking to start it. It always starts but
>>>>> it
>>>>> seams like
>>>>> that is a lot of creaking is this normal or do I have a problem?
>>>>>
>>>>>
>>>>> Jeff Zentner
>>>>> Alta CA
>>>>>
>>>>> 88 5KTQ
>>>>>
>>>>>
>>>>>
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