francesconyc

ok, so it's only 3 weeks i spent with my 1982 911SC
Everything sounded good, and it was always starting immediately, with zero lag. no matter the cold or warm.

Today after spending a couple of fo hours in the traffic between 1st and 2nd gear and a lot of dialing, I stopped for some food,
I rested 30-40 mins tops.
Then when I went to start the car it didn't start right away.
waited, and tried again, but nothing, then I decided to "keep" the key on for a few more seconds and push the throttle, and finally on the third attempt it worked.
It reminded me of when on a motorcycle I'm about to run out of battery but the battery seems pretty new to me

I know for sure the previous owner/s in 201X replaced some parts of the fuel system etc. (i need to go thru th receipt again to be precise)

what are the possible culprits I should be aware of?
I'm curious now to keep it overnight in the garage and see tomorrow morning what happens.

Sajan

Does it crank? Crank slowly?

Mine has trouble sometimes if I try to start after a drive. Cold starts, cranks right up. "hot/warmish" ...cranks (powerful) for longer and then starts up.

Replaced this a few years ago and I thought it was better, maybe it needs to be replaced again.
https://www.pelicanparts.com/More_In...93-906-093-M14

francesconyc

yes, it does exactly as you describe.

I read a very interesting article about this:
this guy's theory is that all the wiring loses conductivity for two reasons: age and temperature. (I do agree because the aging is what makes guitar amplifier sounds better)
so the theory is that when the car is hot, and the car is already 40yrs old, so it already lost a 10% conductivity, it also loses another 10% when hot. so when starting the high energy required loses its strenght.

theiceman

im still not understanding your situation ....

if it cranks very slowly it i likely heat soak in the starter, not uncommon and a switch to a high torque starter will resolve this.

Cranking but not firing when warm is usually due to bleed down of the fuel system, and is attributed to the check valve in the fuel pump or a bad accumulator.

Dr. 914

if it was always "cranking" but not starting, it could be caused by a warm up regulator not offering the correct fuel pressure (too low) or a leaking injector (loading up the cylinder, and leaking down the fuel pressure)

francesconyc

as I said, it DOES start.
when it's cold starts immediately flawlessly.
when it's really hot, it takes ~2 seconds to start if keep the key turned right. not a biggie.

i think the prev owner replaced the fuel thingy, but i need to find the receipt "when" he did it

francesconyc

I should have clarified that it did happen once and only after a 2-hour traffic jam: I remember the oil temp was above half, on the second mark, which was unusual, but due to the constant 1-2nd gear and stop-and-gos

It does NOT happen when I start cold, neither happens when the temp, in general, stays lukewarm/warm
It does NOT happen when I drive on highways and i stop for gas, it starts flawlessly.

bottom line I think one of the theories that overheating wiring/increase resistance can be the cause seems plausible.

but if it happens again, I will check the bosch valve



this is the post i was referring to
https://www.thelincolnforum.net/phpb...ic.php?t=45101

they suggest to replace battery cables with thicker ones

theiceman

its CIS , if it happens that infrequently i wouldn't sweat it and move on , its not a modern fuel system. 2 seconds is not worth worrying about .

francesconyc

Sajan, btw, was it easy to replace that valve?
Im going to troubleshoot this, and I ordered this valve just in case
thanks

Sajan

I had my mechanic do it....so not sure on difficulty.

not sure if it's a different design on the SC vs the 87...but here's what bentley says for 87:

Sajan

francesconyc

thanks. but im starting to think then, it may be due to the starter. i just read an article about replacing it with a hi torque starter and that would solve the problem
https://www.pelicanparts.com/techart...er_install.htm

Sajan

I thought so too and ordered a high torque starter. still sitting here. waiting for an engine drop to swap it out because it might be easier to do it then. I also didn't want to mess with it because I read something about having to add shims?

No crank vs. slowwww crank vs. normal cranks but won't turn over...are all diff issues.

Mine had a slow crank and that one was resolved with a new AGM battery.
Normal crank but turn over when warm...resolved with the new check valve.

considering how much the valve is and (possible) ease of install....do that first. cross it off your list before ordering starter.

francesconyc

actually the starter is much easier to replace yourself than other parts but it requires a ramp or a jack

francesconyc

for sure... i ordered and waiting for delivery...