1997 GMC Sonoma 97 Sonoma. Key on. Fuel injector not on, l

AFIELDS77

MEMBER
1997 GMC SONOMA
6 CYL
4WD
AUTOMATIC
124,000 MILES

When you turn your key to the on positioin but do not crank it over, a few things happen. Your fuel injector turns on, there are about 5 or 6 lights on your instrument panel that come on ( air bag, engine light, beeps start.) And you should be able to apply the foot brake and shift into any gear you want, even when truck is not started. After a few incidences when my truck failed to start then started after a while, I noticed that sometimes these things do not occur when I turn the key on. But then all these things would work and it would start instantly. I say this because i've weeded out the possibility of a fuse. It's to the point that the first thing I do is turn the key to see if these things come on. If they don't I know the truck will not start no matter how long I crank it. But it usually does eventually. Well, it's now been 2 days and it will not start and fuel injector is not pushing fuel to engine, and lights on insturment panel still not on. It is important to understand that it's not something just with the fuel injector, but all these things are connected by one problem. I originally thought it was the ignition switch where the key goes in. But whatever it is I need to know. I don't want to replace 20 things. Just the right thing first. What could it be?

Wednesday, April 15th, 2009 AT 11:56 AM

4 Replies

JDL

MECHANIC
16,098 POSTS

Hello, did you check that the fuse circuit was hot, when it should be? A good fuse won't make any difference, if the circuit isn't hot.

Your saying the vehicle cranks good but won't start? The B+ to the injector/s will go hot with key on, the computer controls the injectors on the ground circuit. No rpm signal, no injector pulse.

With the vehicle cranking, is there spark at the plugs? I can't tell you what to replace, that is your decision. I can suggest what to check. can you check for codes?

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Wednesday, April 15th, 2009 AT 12:31 PM

97SONOMA_POS

MEMBER
6 POSTS

Also, does your fuel pump run when you turn your key?
If it does NOT run, then you know its your fuel assembly, but NOTE: When I did my fuel pump, there was a note in the bottom of the box of the new pump saying: You must replace this connector, GM has found that it will wear out and begin to arc back and forth, thus melting your connector to your fuel assembly(ruining it). ( I wish I would have just replaced that connector before tearing my fuel pump out but. Was only like 8 bolts to take the bed off :p, pain to get that ring to sead in again though)

If it does run, remove the quick-disconnect from your fuel filter, let the fuel drain, and reconnect it. Then turn your key back on and let your fuel pump run (1-2 times) then remove the quick disconnect agian. If fuel comes out a second time, you know your filter is allowing fuel to pass.

Next step would be fuel-pressure-regulator. There is a plastic tube that connects to the regulator, remove that and try to start. IF fuel DOES come out, your regulator is most likely broken.

Those are just a few troubleshooting steps you can take.

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Thursday, April 16th, 2009 AT 7:03 PM

AFIELDS77

MEMBER
2 POSTS

Let me just clarify the problem. I'm not sure if I explained it well enough. When I turn the key to the on position ( one more turn would be cranking the engine over ), SOMETIMES, a group of events, will not occur. These events are the air bag light, check engine light, gas of battery guages engaging, basically a dead instrument panel, no beeps or rings for seat belt warnings, fuel injector not kicking on, not being able to move my shifter out of park even with my foot on the brake. However, the radio still comes on and I can still put the power windows up and down. It's only every now and then, and it's always all or nothing. What I mean by that is it's not that sometimes it will not go out of park and the fuel inj will work. Or the air bag light comes on but the injector does not. They are ALWAYS CONNECTED together. They either all come on or they all stay off. Something connects these things together whether it's in the neutral switch or the ignition or whatever. Sometimes I turn the key and all these things DO come on, I hear the ding, ding, ding, from the dash, and I hear my fuel injector pushing fuel, and I know it with start on the first crank. But if I do not hear these things, it will not start no matter how long I crank. Also whatever this malfunction is, it sometimes occurs as i'm driving. I'll be going down the road and as i'm giving it gas, it's like instantly dead with no fuel, no instrument panel lights, and I have to hope I can pull over somewhere.
I've found recently, after trying various things as i'm stranded, that if I click the key to the first position and kinda quickly slam the key forward, the things come on, and i'm able to start right up. So I wander is it in the ignition, or a loose connection somewhere as I turn the key. But what's weird is my radio still responds to the on position and so do my windows. There is spark at the plugs. Also I do not understand the other stuff your asking. What is the B+ and is the fuse circuit the fuse box inside the car on the driver side?

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Sunday, May 3rd, 2009 AT 10:59 PM

KHLOW2008

MECHANIC
41,814 POSTS

Hi afields77,

The symptoms described are most likely caused by a bad ignition switch, which is known to fail quite often.

When key is turn to ON position, power supply to the dash is missing, meaning all other components would not work and this would not allow you to start the vehicle.

Here are the testing procedures.

Turn ignition off. Disconnect steering column switch 48-pin connector located on steering column. Using DVOM, check for continuity between specified terminals with ignition switch in specified position. See IGNITION SWITCH CONTINUITY TEST . See Fig. 1 . If continuity does not exist as indicated, repair as necessary.