I have a 99 chevy blazer 4 doors, 4wd, 4.3 vortec

The first thing that I saw was that a few days ago the rpm would stay kind of high, will on drive and after the truck was hot already they would stay around 1100, also, there were a few times that it souned kind of rught, like a grrrrr coming from the back of the truck when ever I press the gas pedal kind of hard. Well, today I get in it, and it didn't start , and I don't heard the fuel pump loading like normaly does when the key is turned, the engine turns, but there is no fire, all the fuses and the relays are ok, (what I did to test the relay was swap it with a diferent one that was the same, but no luck... ) I'm thinking is the fuel pump, that maybe it was sending too much fuel at times, and too litle at other times.... ( I don't know, wild guess)

So, what else can I test before I drop the tank, is it a way to test the pump with out droping the tank? what else should I check, and how?

I saw a relay in the engene box, but I seen people talk about another one that I can't see, does any one know where the other one could be? or if my truck has it???

Thanks guys, any help will be very much apreciated, I really need it....

 

i think no1`s answered cuase its a no brainer but i may be wrong,no`1 might not have seen the post yet,either way,1-u said you dont hear the 10-15 sec prime-thus meaning its dead.2-never heard of another relay being the same as a fuel pump relay.(and its usually in the engine compartment fuse pannel)3-check all fuses,if none blown-test light the wires to the pump as close as possible to see if there is power going bk there,4-no power means blown relay or fuse or short,5-if there is power your fuel pump is shot out-replace it sir.hope ive helped for being a N`bie here,they damb sure helped me in my 1st 12 hours here.thanx and happy holidays man.

 

There is a test wire located in the wiring harness above the brake booster. Should be red in color and not attached to anything. Run a piece of wire from the battery positive to this wire. If the pump works, your issues lie else where. If it doesn't it may very well be the pump. The wire is a bypass, it bypasses the relay.

There are two circuits that control the fuel pump, one comes off the ignition switch through the relay. The other comes off the oil pressure sending unit. No oil, no fuel. Its the puters way of saving the engine from massive failure. Make sure you have plenty of oil. Rare for that switch to fail and it might be time delayed.

More then likely it is your fuel pump, mine went out in my '00.
Things to know about replacing your fuel pump.
#1 They aren't cheap, expect the price to be around $280-$350 depends on the one you need, warrenty, and where you get it. It is no longer just the fuel pump, it now includes a new sending unit as part of the assembly. The good news is if your gas guage didn't work right before, it should after you replace the assembly. Caution, not all gas sending units read the same. Some drop faster at first and go slow towards the end, some drop real slow at first and go real fast at the end, some will kick on your low fuel light earlier or later then the one you currently have. Don't run out of gas. Running out of gas is one of the reasons fuel pumps fail. The pump gets lubricated from the gas, no gas, no lubrication. You did get a lifetime warrenty correct?
#2 If the place you call doesn't ask for the alpha-numeric number on the tag, find another place to buy it.
#3 You need the alpha-numeric number on the tag that is attached to the top of the fuel pump assembly, you have to drop the tank to get the number. Know what each store has in stock and how much they cost.
#4 You can go with a cheaper unit, if you don't mind dropping the tank and doing it again when it fails earlier tehn if you spent the money on a good unit. This is one area I recommned you get one with a lifetime warrenty. Unless you have $300 laying around alll the time.

Dropping the tank is easy and straight forward.
There is one bolt and one nut holding the tank strap in place. Remove them and tip the tank so you can see on top of it, the straps should hold it in place. There are 6 hoses, 3 attached to the fuel pump assembly and they are quick connects (come off by squezzing just like the fuel filter), 2 are attached to the filler neck (spray with WD-40 to soften the hoses and unclamp them to remove), and the last hose is towards the front of the truck (spary with WD-40 to soften as well, and use a pair of pyliers to remove clamp. Unplug the wiring harness(s) attached to the fuel pump assembly. Push up on the tank. Gas weighs roughly 8 pounds per gallon, 10 gallons weighs 80 pounds, how much can you bench press? Push up to unhook the straps from the frame. To remove the straps, push the tank up, push the strap up and pull out of the frame. I like to let the gas tank rest on my knees/shins while I am laying on my back, this frees my hands to work the straps.

Now that the tank is out, you can read the tag and get the correct alpha-numeric code. Buy the new part, get a new screen if it doens't come with the kit, also get a new rubber gasket if it isn't part of the kit (should be), and buy a new fuel filter. Do NOT leave the gas tank laying around with fuel in it. The fumes will escape and could explode when they hit a spark or pilot light. I dump my tank into my gas can I use for my lawn mowers. The proper way to store an empty gas tank is by filling it with water, however if your going to be using it soon. Duct tape over the filler tube and if you remove the fuel pump assembly to take with you to the parts store to match to the new part (highly recommended), duct tape over that too. Or leave the tank outside away from any source of ignition and the house incase it does catch on fire.

 

I forgot all of this stuff.
Our fuel system requires about 58-64psi to start the truck, and it should drop off between 3-10psi once running. If your fuel pump isn't pushing enough fuel, its not going to run properly.

 

Just a thought before going to all the trouble of ripping out your fuel tank - there is a fuel line nipple to see if the motor is getting fuel just under the hood near the rear top of the motor (usually) follow the lines. I have a problem with my Blazer where the fuel is leaking back down in the lines to the tank and from what I can figure (with research) is that the intake manifold gasket is sucking air allowing the airlock to be broken, coincedentally the fuel system is housed here. Quick test for this is to pump the gas as much as you can while cranking the vehicle over, also Ether works excellent if the vehicle runs chances are you have an airlock situation - apparently this happens to quite a few of them.