i got a 2003 3/4 ton 6 sp and lately it has been a hard start or sometimese no start without starting fluid it has a p0251 code so kinda have an idea what it could be but not sure any input would be a help and there was a slim key code p0633 and P0541 Low Voltage On The #1 Intake Air Heater Relay

 

i just went through this with my 03. my injectors were leaking down and would not make enough pressure to start. 6 new sticks cured the problem.

 

yup. thats exactly like me.

you arent gonna like it, but injectors need to be replaced. I would honestly skip the denial phase and take it to a shop to get flow tested. then call don m.

1,800 bucks will put you 40hp higher and cold starts all winter long.

 

i kinda see that being it but it seems kinda fishy that that it could be an injector because you can leave it all night and go out and fire right up like new truck but leave it for 10 min occasionally and it wont start thats why i dont think its an injector

 

it will get worse over time. thats the same symptoms mine had. eventually would not start at all without starting fluid.

 

its odd that its always someone with an '03 that goes through this! I swear everytime (including when it happened to me) I read a post with the title "hard start" or "cold start" in it, it would be an '03 having injector issues

I am just glad I went the Don M route, I havent plugged it in since I got the new injectors. I was up in WY a couple weeks ago, it dropped to 16 degrees, and the sucker fired right up. every time.

if you feel its not injectors, it COULD be the grid heater....thats my second guess, but I really do think its going to be injectors.

 

i dunno its getting checked out today so have to wait and see

 

Let me know what you find out today. Mine is just opposite, it won't start after sitting overnight unless I keep it plugged in. Once it starts, it will keep starting all day long.

 

they reprogrammed the ecm that fixed it for a week then same thing then put one injector in and worked 100% sorry for bringing up old thread just wanted to say what was found

 

what about just losing power when it warms up. mine cranks ok. but doesnt have power after it warms up. i replaced the lift pump but no help. when it is warm outside though it runs half way ok. i noticed the other morning that it kinda hic-uped sitting idleing warming up. would this be a injector?

 

Sounds like my problem..no start unless it has been plugged in and if it cools down no start. shop says #4 injector is bad..no biggy, but shop says i should do all 6!? like im made of $$ plus a new lift pump, $3500.00 later im good to go, so i called the dealer they said bring it down since it only has 89,000 on it...BUT..if the mechanic finds ANY dirt in the fuel system and u know they will its a NO WARRANTY issue.looks like i had better come up with the money huh?