starting and stalling when cold

[gvig]

Hi all,

This is a wierd thing. On cold start up all is well, but on moderately warm start (not cold enough to activate higher idle speed), if I start with light throttle the engine will start and run just fine. If I remove my foot from the throttle quickly the engine will idle down and continue quickly down past 500 rpm and them will either die or will hard surge (even belching a small abount of black smoke) up to about 1000 rpm and then immediately idle down and behave itself. The hard surge I don't mind, but often under these circumstances it will die and that means a restart.

This has been this way for two IP's and three FSD's. I think we can rule out the FSD and the IP as a cause tongue.gif

This isn't a major problem as once it is idling it runs great. Never causes any problems other than this one small one. I just compensate for it by not dropping the throttle abruptly on startup. Oh yes, it doesn't like to start with no throttle unless already warmed up. But it would be nice if it would behave itself all the time?

Has anyone dealt with such as this where the IP and FSD weren't involved.

[Barry Nave]

How many miles do you think you have on the injectors?

[Barry Nave]

Just now notice the switches you have in place. How do you work with this. High idle on/off at start. Cold on/off at start. Any combo make any difference? Never had to touch peddle on my 95 though I don't have all the switching.
When it comes to the 94/95 years,thats the Posts I watch the most. Learned alot over the years. The only sad part is when a problem is found and solved,not by all but in part the cure is not told. :(

[gvig]

Banve95,

If I start with the cold start active, or with the high idle active it responds the same as if I had my foot on the throttle. If I switch off the high idle too quickly it goes through the same drop or surge/die as normally. The same is true for the cold start. Unless of course I use the cold start when the engine is actually cold, then the temp keeps the idle up after I switch it off and the problem doesn't show. This idle speed drop and die/surge only occurs at moderate or warm settings and not always, perhaps 60 percent of the time. Anything that makes it idle above curb idle negates the problem. If I allow it to run for about 6 seconds no problem. Whatever has to happen, does so in the first 6 seconds (approximately). After that, all is well.

I also have a relay to operate the lift pump instead of the ops and I don't have any symptoms to indicate a problem there. At least I don't think I do.

[gvig]

Oh yeah, I have about 20K on the injectors, new when installed not reman.

[blshoe]

Hello all,
Im having a stalling problem with my truck only when cold, below 40 deg. Let me give you a little history on this truck. I have owned it for a year and 4 mounts, I got down in Texas. It's a 1998 K3500 crew cab long bed singel rear wheel. The first stalling problem I found was the engine harness had rubbed through and was grounding out on the high pressure A/C line, right where it comes out of thr fire wall, passanger side. But when it got cold last winter, when you key up glow plug light comes on like it should, and you can hear the lift pump working, starts right up and then stall's after about 5 min, or I'll get about 3 milles away. When you go to restart there is no glow plug cycle and no fuel pump cycle. I would have to wait anywhere between 5 min to 40 min and then I get the glow plug and fuel pump cycle and the it start right up, a little loud a first ( 2 sec ) and then sounds normal. Then the PCM failed, replaced it with a new GM PCM. But I was still having stalling problems only when cold out. I have been reading this form for a while and getting some great pointers what to look for. I did find some weak pins for thr ECM-1 and ECM-B min fuse in the under hood relay/fues box, I also found weak pins on the relays, fuel pump/starter. I went through and replaced all of the pins with new packerd pins. I also replaced the glow plug controler,both negative battery cables,and both battery's and alt,and the ground ring terminals on the back of the passanger side head. I also replaced the Ignition switch, Still the same thing stalling when cold. When spring came the stalling went away. Now I got a check engine light for the optical/fuel temperature sensor, but no stalling since it has been warm. Now that it is winter, started stalling again after cold start's. So I through the book at it, New Injection pump (not rebuilt) New FSD on a coller from SS/diesel with ext harness,had injectors tested,new glow plug harness,glow plugs,injection pump harness,timing chain set, crank sensor,coolant temp sensor,map sensor,aircharge temp sensor,boost solenoid.I also changed all the pins on the PCM,some of them had weak pins. Got the truck up and runing, no problems. one week went by and guess what, started it up one morning and it stalled after about 5 min of rining. went to restart and the glow plug cycle was working and it started right up. It has done this a couple of other times to, and has restarted. A couple of days ago I went to leave work and about 5 miles away while driving it stalled. Pulled over and tryed to start but again, no glow plug cycle, I sat for about 20min and finally the glow plug cycle came on and it started right up. I am sorry for the long post but Im trying to give you guys as much details as posable on this little DEVIL in my truck, THIS THING IS KILLING ME. Thank you for any Input on this,

Randy.

[JohnC]

George:

when was the last time you changed the fuel filter? There is probably a brief instant after start where the lift pump is not running. If the filter is loaded, you could have the behavior you discribed.

Randy:

You should create a new topic with your problem so the responses don't get mixed up with George's.

[gvig]

Thanks, I hadn't thought about that one. I will check it out this weekend.

[blshoe]

I did forget to put that down, the fuel filter and the lift pump are new, A/C delco I also checked all the fuel lines. I also put new return lines on the injectors, the truck has about 136,000 miles on it. JohnC, I thought that I should of put this on a new post after I posted this. Can I copy whan I posted and make a new post.
Randy.

[Barry Nave]

I also have a relay to operate the lift pump instead of the ops and I don't have any symptoms to indicate a problem there. At least I don't think I do.

Then this must be a switched item also,being you control the lift pump. I'm thinking our truck don't run the lift pump while cranking, only during run. I do bleed filter change,gear out of park,key to start. This works the lift pump and truck won't run the starter.
Filter,thats one I would of missed to ask :rolleyes: Over at the member area there is a matenance list I print out for my recoreds. I'v kept track of all thats been done sence 98.
Owner then at 45K