Starting when warmed up paranoia

[BFlat]

Drove the 87 Limited 50 miles and got in a long parade. Temp never went above 175. Parked it for about 20 minutes & then had to crank it a long time before it started. Had plenty of battery. New injectors & wiring harness, FP hot-wired, FP relay, TT chip, LT1 MAF & translator. FP at 43. SM numbers are fine, but IAC is a bit low at 6. Anything I could check. A bit afraid to drive it any long distance & get stranded because it won’t start. Thanks.

 

[mblum]

How old is are the ignition components (coil, ignition module)

Heat soak can cause issues on those items if they are getting weak.

What spark plugs and what are they gapped at?

 

[BFlat]

New module & coil pack. New SP wires. Plugs are AC 42s. No go-fast stuff mods on the car, so maybe go to a hotter plug?

 

[mblum]

What are they gapped at? Straight out of the box?

 

[salvageV6]

CR43TS are a nice spark plug for a stockish car.
The fuel pump probably didn't prime at all or well and you had to crank it past 4 psi. oil pressure to get the fuel pump to run again.
I always listen for the pump, if it doesn't start in 5 seconds mine won't. Re-prime, after a 15 second wait, listen, and fire it up.
Driving the car more builds confidence in what it wants how it sounds etc., it's probably not a well shared view here now that people think they are worth a lot. The only reason I replied was I started mine today and it took 2 primes....

 

[BFlat]

I’ll put the CR43TS plugs in when I feel like fighting #6 again. Gap at .035, correct? And I’ll give it a few tries at re-priming if it happens again - which I hope it doesn’t. Amazing how many thoughts fly around in your head when you’re miles away from home and you don’t think the car will start. There’s a buzzer that goes off for awhile when I 1st turn the key. Makes it kinda hard to hear the pump, but I won’t mess with it. Thanks.

 

[BEATAV8]

Try a “clear flood” if it happens again.
Clear flood shuts off the injectors. Floor it & crank it to clear flood
Release pedal once it starts

 

[blackazz]

How old is your fuel pump

 

[SCOOBY DOO]

 

[slojim]

A few hours at 3 mph means you've recirculated your fuel a lot. I wonder if your fuel was hot and that caused some cavitation or flashing or some other problem. I can't explain it, but a parade is different than normal driving so there may be unusual conditions

 

[TurboTGuy]

Had the same issue on my '86 GN WAYYYYYYYY back in the day. A wacky no start, that if you let it sit for 10-15 minutes, would start right back up

Turned out to be a faulty crank sensor.

 

[Turbo1dr]

If your fuel pump relay is bad it could cause long cranking times. Especially after the engine oil gets hot. The oil pressure switch acts as a secondary way to power up your fuel pump in case the fuel pump relay stops working. Cranking your engine when it's hot will take longer to get the oil pressure up high enough to close the internal switch which powers the fuel pump. Check to see if you hear your fuel pump run for a few seconds before you start cranking your engine. If you don't hear it run, it's probably a faulty relay. You can also check for 12v power at the fuel pump prime connector behind the alternator with a test light. Ground the test light and put the pointy end on the prime connector. Turn the key to the ON position (do not crank the engine) and if the test light lights up, your relay is working fine. If not, the relay is bad or the connections could be bad.

 

[BFlat]

How old is your fuel pump

It’s new. Less that 200 miles on it. Hotwired. New filter & FP relay.

If your fuel pump relay is bad it could cause long cranking times. Especially after the engine oil gets hot. The oil pressure switch acts as a secondary way to power up your fuel pump in case the fuel pump relay stops working. Cranking your engine when it's hot will take longer to get the oil pressure up high enough to close the internal switch which powers the fuel pump. Check to see if you hear your fuel pump run for a few seconds before you start cranking your engine. If you don't hear it run, it's probably a faulty relay. You can also check for 12v power at the fuel pump prime connector behind the alternator with a test light. Ground the test light and put the pointy end on the prime connector. Turn the key to the ON position (do not crank the engine) and if the test light lights up, your relay is working fine. If not, the relay is bad or the connections could be bad.

View attachment 406237

Many thanks. I’m copying and saving the attachment. The FP relay is brand new, but I’ll try the check you suggested. This car always seems to crank longer than I'd like, but I’m running out of parts and adjustments to make. Maybe it’s just a slow starter - like me.

 

[mblum]

Do you have a fuel pressure gauge? That would tell you if fuel pressure is present while cranking.