'99 4.3 V6 questions

[53burb]

I have a '99 Chevy (NBS) 1/2 ton Silverado 4x4 with the 4.3 engine & manual tranny. The truck has 130000 miles.
Recently, as of about a month or so ago, the truck stopped starting with just a turn of the key. It turns over a few times before it starts. It only does this when it is cold.
Yesterday, I changed the spark plugs, wires, air filter, PCV valve, cleaned the MAF sensor, new cap & rotor, & changed the fuel filter.
It is still the same.
My next guess is possibly dirty injectors or a weak fuel pump, or maybe weak starter. The fuel pump was replaced with a Delphi unit at approx. 105-110000 miles. It's noisy, but it has been this way for awhile. It also had the "check engine" light on. I disconnected the battery while I was changing everything, so that "check engine" light is now gone, but I'm sure it will reappear. I had it checked before & IIRC, it said one of the banks was the culprit.
So my questions are: what is a good brand of fuel injector cleaner & can the timing be set on this engine, or does the distributor only have to be installed correctly & the computer controls the timing?
I don't have a gauge to test the fuel pressure.
Any other suggestions?

Thanks,
Chris

[scotts62]

So it cranks a few times over before it starts but does in fact start and run? Sounds like fuel pressure to me, try (before you start for the first time) to turn the key a couple times to the accessory and let the fuel pump prime good and see if that makes any difference.

[truckdude239]

my friends 03 zr-2 s-10 with 4.3 does the same thing what we do is turn teh key to the run postion wait for the pump to kick off and the keey off then back on wait for pump to kick off and then start the trucks in his case the fuel pump is going out and letting the fuel running back to the tank

[53burb]

I did this test this morning. It started right up. Tomorrow morning, I'm going to just turn the key & see if it turns over a few times before it kicks on.

[scotts62]

Check the fuel filter sometimes if it is changed and not installed right it could bleed off it's prime but then it could drip gas a bit..
Have seen the rubber lines in the tank on the fuel pump go bad and get a hole in it and cause it to do what yours is doing also, just a few things to check.
Posted via Mobile Device

[53burb]

This morning the truck started normally....I guess I'll try again later today or tomorrow morning again. Any chance this is related to the fuel pressure regulator?
I changed the fuel filter a few days ago & verified it doesn't leak, but it was having the starting problem before the replacement.

[53burb]

Just turned the key like normal, it started instantly. I know fuel pumps, being electric, can be intermittent, but I think I am going to replace the fuel pressure regulator.

[scotts62]

Wouldnt hurt i guess, hope it keeps starting good.

[bwood]

Have you tested the fuel pressure? It should 55-60. Turn the key on without starting and record the pressure. It should stay steady for a little while after the pump shuts off. If it drops quickly, it could be the regulator, the fuel pump bleeding off in the tank or a leaking injector.

[53burb]

nope, I haven't tested the pressure yet. The reg should be easy to replace, so I thought I would do that first.....Where is the regulator at? I just tried to find it & I didn't see it. This is for a 4.3 V6.

[bwood]

The regulator is inside the upper intake, still not hard to replace, just more to take off to get to it. Here is a pic of the regulator on the V8 injector assembly.


While you are in there you can remove the poppets valves and look at them. The injection system on this engine is a little different. In the pic below, where the regulator is mounted, this is the injector assembly and the little "tubes" that plug into the intake are poppet valves. These can leak or clog up and cause running troubles.


You truck shares the same (minus two injectors) injector setup as the 96-99 V8 Vortec engines. The first pic is with the newer MPFI injectors installed and the second pic is from the internet showing the original CPFI setup that came in these engines.

[53burb]

Thanks for the pics!! Is there any seals and/or gaskets on the upper intake?? Or can I just remove it & R & R the reg??

[bwood]

You will have to remove the fuel lines and each one of those has an oring, there is an oring around the injector assy (the big plug right in the middle of the intake and the oring that seals the upper intake to the bottom. Before you but any of the sealing orings I mentioned, check out the injector assy for damage/wear. If you end up with a new one (make sure the new one is the newer MPFI version), it will come with all the orings.

[53burb]

Maybe I should check the fuel pressure before I tear into it. Do you happen to know if the auto parts stores rent the gauge/fittings?

[bwood]

I don't know for sure, but they are about $30 for your own. They come in handy.

[53burb]

No update yet. I have the reg, but I haven't replaced it yet. We are in the process of moving & renovationg the house we are moving into, so this isn't a priority yet. Just wanted to say thanks & I appreciate everyone for contributing to this post & I will update it again after I replace the regulator and/or fuel pump.

Chris