I'm not sure how many of you guys are mechanics; but I am one; have been for years. Having said that JP's blazer is a 4.3 vortec, (maybe he didn't mention that in his post) nothing like a standard 4.3 TBI engine. As I said previously, a fuel pump leak down test on a vortec only proves the fuel pump check valve and fuel regulator is holding pressure; it doesn't test the spider in any way. As for a 4.3 not starting with no CTS signal, that's a first for me; that's how I've drove several back to the shop when the CTS went out of range and was flooding during starting. (showing a coolant temp of -40 and therefore dumping way too much fuel to start). JP, get it to a good shop up your way and see what they can do. I'd start with a data check to make sure all sensors are in range and crank/cam signals are good, then if all else fails, open up the intake and check the spider.

 

I sure did not know, the reason I found out was I wanted to check my coolant temperature sensor, and of course where its located on a 92 S10 4.3 Vortec W coded engines its very difficult to check with the leads from a multimeter. So I bought a new coolant temperature sensor connector pigtail.

Unhooked the connector coming from the computer to my coolant temperature sensor at the engine, Hooked the new pigtail to it, them got a reading with the engine cold. Them I went to start the engine in order for the coolant temperature sensor to warm up and get another reading. Guess what, it would not start.

At 1st I thought something had gone wrong, them I thought, could it be because the coolant temperature sensor disconnected from the computer the reason it will not start?

I took the pigtail off, plugged the one coming from the computer back up to the coolant temperature sensor on my engine, bingo, my Blazer starts.

I can't say what other 92 S10 4.3 Vortec W coded engines will do, but mine will not start if the coolant temperature sensor is disconnected, and it will when reconnected. Yet I would guess that it would affect at least all 92's the same way.

Plus, I can say this about my engine, yes if there is a leaking fuel injector spider line mine will not hold the needed pressure when turning the key switch to on without starting the engine. I know from hands on experience, for mine would not, yet when I replaces the spider injector it would hold the needed pressure, plus it would start

Now once again, I can only say what my 92 S10 4.3 Vortec W coded engine that I bought new back in 1992 will do, yet I suspect all 1st generation 4.3 Vortec W coded engine will do the same as mine, for it has never had no modifications of any sort.

 

Not really true for either the CPI engine (92-95) or the SCFI engine (96-02). It doesn't test the spider past the injector, that part I will agree with you on. But the main spider body on the SCFI spider in JP's truck doesn't have any pressurized passages after the injector. So in essence, you are testing the spider body itself.

You are correct that a leak in a line would not show up in a leak down test. This can be diagnosed by removing the throttle body, leaving the sensors connected, disconnecting the MAF sensor and the main coil wire (so the engine doesn't fire). Using a mechanics mirror and a light, inspect the lines through the opening in the upper plenum while someone cranks the engine over.

Another condition that may be present is clogged poppet nozzles that could allow the pressure to leak out into the intake port when the electronic injector is not open and/or result in a poor spray pattern. To diagnose this, you really would need to pull the upper plenum off.

 

I found a replacement fuel injector by AC Delco that has the injectors on the end of the line now, eliminating the needed for a poppet. I've also heard that this will also improve the fuel economy too.

 

Definite improvement in reliability. If the old spider had gummed up injectors, then it will result in improved mileage as well.

 

Updating.

So we replaced the Spider. Put everything back together right. Tried to start things up with no progress

The engine is doing the same sort of thing it was doing before we removed the upper plenium and switched the spider.

We got a manual and checked the MAP sensor for voltage as well, everything was good.

Uncertain about what the problem may be now.

Next Step is to have it Towed to a garage and have them hook it up to a scope.

If anyone has any suggestions please tell me.

JP

 

Replaced the throttle position sensor today.


Still No Start.

 

Got it running over the weekend!!!!

It runs Perfect Now! Such a simple solution...I will write more later.

 

Alright. So after everything that we did we decided to get the truck towed to a shop and hook it up to a computer to read all the sensors. Everything checked out perfect!

The shop disconnected the fuel lines and hooked the truck up to a motor vac system and it fired up, it was a rough idle but it ran! They checked the BRAND NEW plugs after and noticed they where black and full of carbon...After replacing the plugs again, the truck fired up and ran like new!!!

As I had mentioned before about replacing the fuel pump...well I guess when we did it, we neglected to notice that one of the lines and come under a strap that cause it to pinch over time. (the lines where replaced a few years ago with nylon lines)

So the line that was pinched was not the fuel line, but it was the return line! This was causeing the presurre regulator to open up and spray way more fuel then needed casuing major flooding and allowing fuel to go into the oil! about 95psi!

Such a simple mistake!!!

The truck runs like new now!!

And we know a lot more about the blazer than ever before.

Thanks for reading and trying to help out. If you have any questions about our situation do not hesitate to private message me send me an email. jpincanada@gmaill.com

Caio 4 Now

 

this problem sounds exactly what i am going through right now check https://blazerforum.com/forum/showth...er+running+bad

any help would be nice
me and my dad did the same thing with the pinched fuel lines lines, that fixed, but still not running right
not cat, replaced the fuel relator, tested and cleaned almost everything I could