No start..where to start?

[blowby]

Ok here goes....

I'll admit up front that I'm new to the newer GM's. ('80's and older I'm fine)

Mostly a Ford guy, but I do love my Sub.

Please forgive me if I ask some seemingly dumb questions as I learn more about the emgine systems on this thing.

 

I have a 1996 Sub. with 5.7 vortec. 238k on it and up until a few weeks ago it was running fine.

Truck had a recent "tuneup" just before I bought it,(1yr ago) looks like new plugs and wires for sure.

It met Penn. State emissions.

 

2 problems that occured together and I'm doubtful they relate but maybe, so I'll describe both.

 

By the way, the SES light never came on nor flashed.

 

1) The engine recently has had some intermittent "hard starting" issues...they seem like the timing is off, by the way it turns over. It did that a couple of times but with a little persistance the truck wuld start and then run fine for a month or so before it did it again.

This has happened 3x, the last time is where i am at right now.

It cranks hard and then freely as if the timing is being adjusted as it is cranking.

It pops and backfires through the TB, but will not start.

I can hear the fuel pump running and the backfiring would rule out a fuel supply issue.

 

2) This is the second issue, that occured just a couple days before the final truck restart issue.

The Brake system seems to have a short?

 

Headlights off:

Press on the brake pedal and the parking lights and guage lights come on.

The left turn signal will not flash but stays on (left only, right is fine)

Cruise will not work.

 

Headlights on:

The 3rd brake light stays on, left turn signal still wont flash(right side is still fine), but cruise will work.

 

Any help is appreciated.

 

thanks,

 

Bryan

[90GMCZ71]

Just because you can hear the fuel pump does not mean that you may not have a fuel issue. Fuel pressure should be 60 - 65 PSI for you engine. You need to measure the fuel pressure for the following conditions:

 

1) Cold Start pressure

2) Hot Start Pressure

3) Pressure 5 minutes after the engine is shut down

4) Pressure at idle

5) Pressure at 2000 RPMs.

 

The fuel pressure regulator is known to leak and is located under the plastic upper intake. There is an updated central fuel injection kit. This kit is a redesign for the leaking poppet on the central fuel injector.

 

First things first, is to look at the fuel pressure to make sure you don't have a fuel issue for your hard starting.

 

//90GMCZ71

[blowby]

I'll check the fuel pressure then.

 

But what about the hard cranking?

It sounds like a timing issue when it's cranking.

[90GMCZ71]

I'll check the fuel pressure then.

 

But what about the hard cranking?

It sounds like a timing issue when it's cranking.

 

Is the hard cranking cold, hot or both? If it is when the engine is warm, then a leaking fuel pressure regulator or leaking injector poppet can cause a hard cranking problem. It can also cause a backfire.

 

//90GMCZ71

[blowby]

Ok, thanks for the suggestions.

 

The starting problem was due to the good ole' cap and rotor....

I replaced them and that did it. They were a bit corroded, after 20k miles.

Not GM's greatest design..

 

Anyway, glad it was an "easy fix",

Kinda surpised that a cap and rotor could cause the symptoms I was seeing.

But now I know.

 

Now I just need to figure out my "short" issue...

Any suggestions or anyone have similar issues?

 

Bryan

[blowby]

The "shorting " issue turned out to be a set of partially corroded contacts on the Drivers side tail light assy.

 

thanks, for all the advice.

 

Bryan