Help please, '88 5KCSTQ needs at least 3 hrs rest!
Louis A. Mulieri
mulieri at physiology.med.uvm.edu
Sun Nov 30 20:56:51 EST 2003
My 1988 5KCSTQ cranks a loooooong time if I try to start it after a 1 hr
cooldown from normal driving temperature. Sooner than 1 hr and it starts
in a few seconds but from 1-2+ hrs after normal running it cranks up to 1
min before firing a few cyls and then stumbles along for another 15-20
seconds before coming to life. 3-hrs or overnight rest and it starts
instantly so it seems unlikely to be leaky injectors.
I had long cranking even after overnight rest this summer whenever the
outside temperature was above 78F.
There are no fault codes registered. Energizing the fuel pump with a
jumper wire (pump sounds good) for 30 sec before and during turning the
key to start does not eliminate the long crank time during the 1-2+ hr
I replaced the fuel filter underhood and checked fuel delivery rate as
well (750 cc/30 sec as per Bentley).
I suspect the temperature sender that signals the cold start valve
controller may be erroneously indicating "warmed-up engine" when it's
cooled down for 1-2 hrs when it should be indicating "cold engine".
>From Bentley I concluded the likely temp sender was the double-spade
terminal one pointing toward back of engine out of the top goosneck and that it
should be a resistance unit rather than a thermal switch. Ohmmeter check
revealed open circuit between terminals as well as from each terminal to
ground. Jumping the terminals with a fixed, 1 kohm resistor did not
eliminate long cranking.
Ordered a new one (22 mm brass hex housing with red dot on nylon
base of terminals and 9 mm threaded end into block, stamped: 07-93 and
110-97, 130 C max). The new one also reads open circuit regardless of
ice-water or flame exposure. I'm confused as to whether the new sender is
bad or that I'm not looking at the right one on my engine.
There are two other temp-like units screwed into the water jacket in this
area. A small one with a single spade terminal screwed directly into the
head ahead of the top goosneck and a large, 4 or 5 terminal socket one
pointing downward from underneath the top gooseneck.
Can anyone help me to identify which sender is the one used by the
computer to control when to pulse the cold start valve and what it's
temp-resistance readings should be and/or what other causes there could
Thanks for ideas,
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