Truck starts fine cold but won't when it's warm

[Sganderson]

Hey I have been having this problem ever since I've owned this truck. I have an 88 k5 that starts great when it's cold but if I turn it off after I've run it awhile I have to wait 10-15 minutes before it will fire back up. It turns but it's slow and will not fire. I've put new spark plugs ,wires and a new starter in it but no fix yet. Battery is good, I've had it tested at my parts store. I'm just leaving it on whenever I stop somewhere now and it's eating up my gas. I've had a few suggestions ranging from bad fuel pump to faulty oil pressure sensor. Has anyone ever had this problem? Does anyone have suggestions? Thanks and I appreciate any answers.

 

[Deuling]

Sounds like timing or a heat sink issue.

 

[79rustyk10]

Maybe try new battery cables. Heat increases resistance dramatically. I'd check the connections too.

 

[paratrooper307]

Are you running headers? Depending on the design or the level of heat if the starter gets to hot it won't want to work. Connections can also be an issue, if you have any that are suspect it can cause connectivity issues as things heat up. If you have a marginal relay as well, they stop working when they get too hot.

 

[Carcinogen]

Are you running headers? Depending on the design or the level of heat if the starter gets to hot it won't want to work. Connections can also be an issue, if you have any that are suspect it can cause connectivity issues as things heat up. If you have a marginal relay as well, they stop working when they get too hot.

This.

My old S10 would do that, turned out to be the starter solenoid was overheating. A cheap starter heat blanket fixed that issue.

 

[Sganderson]

Thanks guys. Will wrap starter and solenoid and check connectivity and also battery cables. Will update after

 

[Stomis]

Sounds like timing or a heat sink issue.

 

[Sganderson]

By heat sink issue , does that have to do with the ignition module?

 

[Stomis]

By heat sink issue , does that have to do with the ignition module?

No heat sink isnt the right wording. Heat sink is a computer part in general. Its called HEAT SOAK. It happens when the engine/exhaust get wires or electronics so hot the resistance shoots through the roof and causes issues until they cool off. Common with starters and headers.

 

[Sganderson]

No heat sink isnt the right wording. Heat sink is a computer part in general. Its called HEAT SOAK. It happens when the engine/exhaust get wires or electronics so hot the resistance shoots through the roof and causes issues until they cool off. Common with starters and headers.

Ok thanks

 

[chulisohombre]

Yep starter is getting hot and solenoid not wanting to engage til the engine cools off. Lines doing the same thing. Need a starter heat blanket or the fold solenoid can also help by moving the solenoid away from the headers.

 

[Sganderson]

Update

Found the problem. I bought this truck last September and while me and my father were adjusting the timing on it he noticed my battery only had 440 cca. So even though it was a good battery it was just too weak. So I swapped it with an 850 cca battery and it's cranks like a champ now. Problem solved. Thanks for the replies everyone.

 

[diesel4me]

My 6.2 in the 82 GMC is pissing me off --just had to jump start it to leave my doctor's office..it cranks over like gangbusters when its cold, and fires right up..after I drove it 5 miles and let it sit there a good hour (and it was still fairly hot under the hood),it went "click"...did this before last week on me too,luckily it started after a few more tires..(and I went thru the agony of dropping the starter,taking the solenoid apart and cleaning the contact disc inside ,even though it looked OK too)..

I tried starting it a few more times,and left the key on "CRANK" and it eventually started turning over slowly,and it almost started,then it started slowing down to the point it was not spinning fast enough to start--so I got my jumper cables out and hooked up another old battery I had in the cab to the one on the drivers side,and it whipped right over and started..

I noticed the positive cable from the drivers side battery was quite HOT where it meets the passenger side battery,so I'm thinking the battery on the passenger side is probably going bad,and soaking up all the juice from the other battery ,and keeping it from getting to the starter ,once the engine and starter are hot and need more amps..

I had removed all the cables the other day at the batteries and cleaned all the connections off with a wire brush on a dremel tool,so unless the cables themselves are junk (and might be,they look original),I guess I'm going to have to buy batteries for it..

What baffles me is after it cranks slowly and seems like the batteries "die",a few minutes later it will crank normally and start, so I am going to look the cables over good,maybe make a new one from welding cable to go from the drivers side battery to the passenger side,that one looks like an OEM 4 gauge one..

If my sore neck feels any better later on,I am going to swap the drivers side battery to the passenger side and maybe not even hook the other battery up at all,and see if that makes it start better hot...if I had a load tester that would make it easier to see if one battery is dying--was thinking of going to Autozone on my way home and have them load test my batteries,but that requires dissconnecting them,and I didn't feel like trashing my good clothes with battery acid..

I was going to go get my prescriptions filled right after the doctor visit,at the drug store practically next door--but I figured I'd better just head straight home before I ended up stranded there--wanted to go get an inspection sticker on it today (IF the p-o-s will pass,its doubtfull,but I at least have to try,it expires in 4 days..)--but I am leaving that to tomorrow...right now I need to just lie down and get rid of this aching neck and back,and am glad I just made it back home.......