Intermittent Start Problem

**eglmrk** · 03-06-2008, 09:55 AM

I have a 99 GMC Suburban. It has an intermittent start problem... perhaps one time per month. I've replace fuel pump and filters. I can hear the pump run. The engine turns over as if burning a prime of gas and then stops. I've also notice (sometimes) that the security light comes on prior to this happening. It also occurs more after a rain than good weather. I was told to turn the ignition on then turn it off. Repeating the procedure three times. The problem is that I can't remember the length of time for each. I believe it is supposed to re-set the computer. Can anyone assist?
Tom Markley

**MrShorty** · 03-06-2008, 11:55 AM

cycling the key might reset the computer. Or it might just be to give the fuel pump adequate run time to pressure the fuel rail. Or maybe to reset the anti-theft security system. It seems that the anti-theft system causes it's fair share of no starts like this, but I don't have any experience diagnosing it. Beyond that, I'd put a fuel pressure gauge on the fuel system to see if fuel pressure is where it should be (50-60 psi) and see if it's getting spark.

Just in case, I'm assuming that we are talking about a gasoline engine. On the off chance you have a diesel engine, disregard. I don't have any experience with diesels. It might help if we knew which engine you have in that '99.

**eglmrk** · 03-06-2008, 01:29 PM

Thank you for your response. Is there any way to disconnect the security system to see if it is the problem? In the althernative is there any other way to reset the security system/computer?

Thanks again for your response.

Tom Markley

**MrShorty** · 03-06-2008, 02:53 PM

I don't know anything about the security system, so I don't know. Similar threads previously posted.

http://www.gmtruckclub.com/forum/sho...light=security
http://www.gmtruckclub.com/forum/sho...light=security
http://www.gmtruckclub.com/forum/sho...light=security

**tbplus10** · 03-06-2008, 07:30 PM

Is it a factory installed Security system with a chip in the key?
If so I had a similiar problem on my 91 Firebird, about once a year I had to mess with it. I replaced the key twice (in 15 years of owning it, a chevy parts dealer item that runs around $50). I also cleaned the key with electronic contact cleaner a few times. If I remember it was impossible to disconnect the system because it was integrated with the ignition system, radio, and power locks.

**Gmcsuvguy** · 03-06-2008, 07:59 PM

You need to retrieve the codes out of the computer to see what is happening. If it is the security system or if it is the ignition system. Do you have a remote starter in your truck? I've seen them cause alot of security problems also.

**30 Yr GM Tech Burn-out** · 03-14-2008, 02:00 PM

Gm suv guy is right...You need a Qualifyed tech to scan the system. If I remember right. You can manually reset the security system by turning the key on...Waiting till the security light goes off wait less than 10 seconds, then repeat as many as 3 times. May take 30 min. The truck will start. Your truck is equiped with a "passlock system" Fairly simple. Involves key rotation signal to the control module. Sometimes the Ign SWITCH asm will have to be replaced to fix it...If your truck has a bunch of miles on it..Id change that first. You do not have a pellet in your truck key.(thank god for getting rid of that) If you do have aftermarket alarm- start stuff on your truck...I would disconnect temp. during diag..(Normally with a totally quiet, no starter op.) I think yours is cranking and not starting. The security control mod is burryed dead center of your dash. Youd just about have to buy a new one to find it....Its fun to replace. Didnt want it to be easy for the BAD guys! PS I dont think YOU can easyly bypass the system. It takes out the fuel system ect.