5 seconds of cranking to start

Cody Forbes cody at 5000tq.com
Mon Oct 8 19:14:32 PDT 2007

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
'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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