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niemo
10-17-2003, 17:11
Last week truck would not start, went to dealer they said it was the Mass Airflow Sensor. They replaced sensor and everything worked fine till today. This morning I start truck and it runs for about 10 seconds and dies. It never started again, it would just turn over. Truck gets towed to dealer where they say there are no codes and they have yet to figure it out. Does anyone have any ideas as what it could be? The only mods I have are a 4" exhaust and AFE filter system. The truck has been pretty good to me. The only other repairs I have had was the fuel pressure regulator in Sept. '03 and some computor updates way back some time.
dmaxalliTech
10-17-2003, 17:46
sounds like loosing prime possibly. Prime it then try, does it start?
niemo
10-17-2003, 18:26
I tried this, I have fuel at the vent when pumped, still doesn't start. I thought that was the problem last week or a dirty filter. So at 5:30 am I was changing my fuel filter with no success.
dmaxalliTech
10-17-2003, 18:44
after you close the vent and pump till primer is hard, does it start?
niemo
10-17-2003, 19:58
No, I'll pump it and it still will not start. I'm not sure what's going on I only have 45k miles on the truck.
Dr_Crane
10-19-2003, 17:17
One of the ambiguous answers I got from dealer when my truck had no start condition was that no fuel was coming out of the filter housing when it was pumped, I guess it was building pressure internally. This led to them replacing the filter housing. A simple test would be to remove the outlet hose from the filter housing, pump the primer and see if fuel actually flows out. This is just a guess on my part, dmaxallitech is really the one to talk to. Good luck!

Mike
niemo
10-20-2003, 07:19
Well I just got off the phone with the dealer and they still have not figured it out yet. I'm becoming a little worried.
mdrag
10-20-2003, 07:48
A few thoughts - crank sensor or alarm system.
niemo
10-21-2003, 03:06
Well the dealer calls says the truck is running but there where no codes and they have not done anything to the truck. They say if there are no codes they don't know where to begin. So I brought the truck home last night, runs great no problems. Get in this morning to go to work it runs for 5-10 seconds dies and won't start. Same as last week. I not a mechanic and don't no very much about these trucks. I've tried the alarm thing by leaving the ignition on, so any help would be appreciated.
Mdrag: What,where is a crank sensor? would this not show a code if this was bad?
niemo
10-23-2003, 03:49
Well I should have read your post a little more carefully dmaxallitech, I was only pumping until I got fuel at the vent, not till it was hard. My truck started right up after priming it Wednesday morning so I take it back to the dealer tell them what I discovered. They have had it for 2 days now with no success, supposedly have talked to GM tech support with no answers. Where do these trucks normally get air into the system? They changed my fuel pressure regulator about 3 weeks ago then a week later I begin to have problems. That's where I would look but they say they have checked it out and there are no leaks. Any ideas would be appreciated.
Kennedy
10-23-2003, 17:27
My experience has been that the fuel is vaporizing ("outgassing") in the lines as it is heated and exposed to reduced pressure. No starts as a result of this are not all that common, but do occur. The addition of my filter kit has aggravated this condition on some trucks, but many more have no problems. One thing that may be happening is that the ones that experience this may have a very minor leak somewhere in the system. When the vehicle sits, it allows air in. This condition could well have been created when the pump regulator was removed from your truck...
NWDmax
10-23-2003, 17:49
I know when I've changed filters and gotten air into the system it takes days and multiple bleedings to get all the air out.
The fact that I have a Mega filter may make a difference but I think the air takes awhile to work its way out even in the stock system.

JK any idea yet on the fuel pressure gauge release date?
Blake
mdrag
10-23-2003, 20:42
niemo,

Sounds more like a loss of prime problem. The CRANKSHAFT POSITION SENSOR (http://community.webshots.com/photo/76034334/96288846rFcnSt) can be seen in this picture, taken from underneath the truck while on a service lift. Not the best pic, but it should give you an idea where to look.

BTW, this picture is Allimax's truck. IIRC, he experienced a no start problem, eventually found to be the crank sensor :eek: I don't recall if it set a code....
niemo
10-25-2003, 08:10
Got my truck back yesterday and it started this morning, so all is well back at my house. I didn't get to talk to service writer about repairs but the ticket said they replaced a hose on supply side of fuel module.