Blazer won't start (another unique)

[ken_man_1]

I have a 2000 Blazer LT, Vin code W, 4.3 liter Automatic.

Running fine then nothing after parking it for 6 hours. Diagnosis as follows-

Engine cranks over but does not start. Checked for fuel delivery, we have pressure of 53psi and it holds for over an hour while sitting still. checked for spark, we have a nice blue spark. Checked for spark at cylinder 1, we have spark thru the distributor cap. Checked for injectors pulsing, they are pulsing.

Ok...I'm in the process of pulling the plenum cover, so I can see if there is any fuel leakage inside. I did buy a new pressure regulator, but I'm not sure that is the problem.

I sprayed starting fluid in the intake, and it pops off but doesn't stay running (lack of fuel to cylinders????).

Battery voltage is good, no blinking dask lights or anything like that...just won't start.

Any suggestions? Please help!!!!

Thanks in advance for your time and any help you may have.

~~Ken

[BlazerLT]

53psi is low.

You should have 60-66psi with that truck with the key on and the engine off.

Check for a plugged fuel filter or have the fuel pressure regulator checked along with the fuel pump.

[Fireplug]

Fuel pressure way to low , even a 3 to 5 pound drop will cause a no start

I sprayed starting fluid in the intake, and it pops off but doesn't stay running (lack of fuel to cylinders????). you found your problem and you did not even know it

[thequin88]

Try checking all connections from the battery, starter, and altenator. I'm new, but it seems to me that you missed step one. Maybe, I am just dumb.

[ken_man_1]

Alright...here's what I found out. I talked to a GM Tech (10 years), and he told me that typically when a fuel pressure regulator goes out on these, it floods the cylinders. Well guess what!! After testing all of the injectors with my ohm meter, they were all good. Then I replaced that fuel pressure regulator and tested for output from the injectors (applied 5 volts across the injectors pins) and I got fuel out of them. I then decided to reassemble the plenum and giver...started up immediately!

I hope that helps someone else because it was one of those things that even the tech overlooked. $60 bucks from Napa, and I am on my way.


Oh, and btw...you guys that notice the hesitation when you first take off...I had it too, but it's gone now.

Thanks for your time...it's much appreciated.

~~Ken

P.S. My pressure was maintaining at 53psi when sitting without the pump running....when it did prime, it was up at 66-68psi...I double checked it when you said it was low ~~

[ken_man_1]

Alright...replacing the pressure regulator seemed to cure the problem...up front. Now it's starting hard (if at all) when cold. Reading from numerous posts about this, I've gone back and checked fuel pressure, and sure enough it's sitting at 50psi cold after priming. Fuel filter was changed and now it looks as if I'm going for a fuel pump
Fule pump could have caused it the whole time I guess....

~~Ken

[BlazerLT]

Again, you require 60-66psi for that engine.

Have you changed the fuel filter?

[ken_man_1]

Yes, and I looked at the pressure...it now drops down to 25 sitting still. from prime to 5 minutes later it drops to 25. blagh...nice chevy...nice chevy.

[BlazerLT]

Pump or sending unit is shot.

[ken_man_1]

BlazerLT - you are right again. I replaced the filter 2 months ago, but I've gone thru and done it again just for the sake of being thorough. I wouldn't think that a pugged filter would allow the fuel pressure to drop while sitting still...so I replaced the pump as well. Although the truck starts like normal again, it seems like it has a little hesitation and a slight loss of power. I've read some threads on "poppets", and thinking that maybe one is sticking...but we're back on the road again!!

~~Ken

[BlazerLT]

When is the last time you did a tuneup?

Also, spray brake cleaner through your MAF sensor to clean off the sensor filaments.

Do this with the MAF sensor out of the vehicle.

[ken_man_1]

Like I said b4 Blazer, you're a genius! I did a tuneup about 4 months ago, and it was complete from plugs to rotor, including the air and pvc's. I did not know about the brake cleaner thing, I'll do that this week. Thanks again for your high level of tolerance...

~~Ken

[BlazerLT]

No problem, only here to help.

Also, you can use carb or TB cleaner for the job. The MAF filaments should be shiny metal. Spay the cleaner on and allow it to melt the sensor filament gunk off.