Just as the title says car won’t turn over in the cold but runs really strong and starts fine when it’s warm. Stuck seafoam in it to try and clean it out to no avail, help.
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some clarification…
won’t turn over… does that mean the starter won’t spin the engine when you turn the key???
if so… test light… behind the brake pedal is the steering column wiring connector… this is a slightly later model…
https://i.imgur.com/rEeRHPL.jpg
do you see the yellow wire… back probe the connector with a test light hooked to ground… do the test light turn on while you are in the cranking position…
if you are saying the engine cranks but won’t start…
pull the fuel pump relay from the underhood fuse block…
check the extraction force… check the insertion force…
pop the cover off the FUEL PUMP relay in the underhood fuse block and check the wear on the relay contacts… i have found them so warn that they don’t close all the way… reinstall bare… squeeze the contacts… does the fuel pump come on… while holding the contacts closed… get somebody to start the engine… release… then unplug the fuel pump relay… does the engine still run… if it dies then you need to replace the 3 wire oil pressure switch… as it has redundant contacts for the fuel pump power circuit…
you may be only running on the oil pressure switch contacts… which is why it will restart hot. but not cold as the oil pressure to the switch is not enough to close the contacts in it cold…
i have found the relay socket pins loose. needing to be tightened up with a thin probe from the side under the folded tongue… this exerts more force on the pins…
which way… to crank or not to crank cold…
i have worked on a lot of 98 chevy pickups…
Starter turns but getting down to about 20 degrees f it won’t run at all, if it’s like 30-35 deg f it eventually starts and once it does its fine.
96 to 98 chevy underhood fuse block…
https://i.imgur.com/Vl1PUmw.jpg
so you can see which is the fuel pump relay to change …
change the the fuel pump relay… i bet that is your issue…
its starting when the oil pressure comes up enough to close the switch in the oil pressure switch… nothing to do with the gauge sender but in the same part…
remove the fuel pump relay cover. i bet the contacts are burned away…
this is the exact problem you describe…
i have found several 98 Chevy trucks with blocks of sponge in the underhood fuse block holding the fuel pump relay in place…
So it was def a problem cause the first time I tried to start it after replacing that relay at about the same temperature, it tried to start but sputtered out and it did it like 10 times before it actually turned over, but before it wouldn’t try to sputter at all until like the 5 try. I’m thinking plugs at this point
how is the ignition coil looking on the outside…
external dust circles indicate external high voltage leaks…
you can use a spark plug… with some wire wrapped around the hex and connected to a good ground to unplug the coil wire from the cap and see if you are getting a bright blue snappy spark…
if you only get an dim orange spark. replace the coil…
on the fuel pump relay… did you check the insertion and extraction force of the relay in the underhood fuse block…
I talked to the previous owner and plugs were done a couple months ago I guess
Ignition coil passes the eye test, I don’t have time to pull a spark plug atm and I was letting it run for a little while to charge up the battery after the 30 attempted starts and yes the pins have good retention
The easiest way to test the fuel pump is to spray starting fluid into the intake manifold. If this is a Vortec 350, you’ll have to spray it between the air filter and MAF sensor-- just get MAF-friendly starting fluid. If it starts, there you go.
Depending on how cold and warm you mean, it’s possible that you have a loose, corroded, or otherwise bad ground or battery cable. Warmer temp can expand metal bits just enough to connect, but shrink back up when cold. Sounds ridiculous but it happened to me in a 99 Suburban.
I should edit original post, it does crank, but just won’t start no matter how many cranks after it gets below about 25 degrees f
