I just got my 96 blazer with the 4.3 vortec and it won't start unless you spray it with starting fluid. Fuel filter is clear. So what could be my problem? Plus when I do get it started I have to feather the throttle or it will die on take off. If u push it too hard it spits and sputters. Could the fuel pump be going out? I'm a newbie to trucks any help would be great.

 

Welcome to the forums, Adam. And congratulations on your "new to you" Blazer.

You know the fuel filter is clear how? Did you actually replace it? Or did you just disconnect it and see clear fuel from both sides?

Fuel filters are the most neglected item of regular maintenance. They should basically be replaced every time the air filter needs replacing. If you have any doubt, replace the fuel filter first.

Next question is, is it always hard to start? Or is it hard to start the first time in the morning, but starts OK after it's been driven and shut off for only a few minutes?

What is your fuel pressure at the pressure test fitting with the engine off, key on for a few seconds, after the system primes? You can often get a fuel pressure gauge setup at your local parts store as a loaner/rental. Start by testing the fuel pressure at the test fitting. It should be at least 60 psi for your engine (I'm assuming you have the "W" in the 8th position of your VIN, and the CSFI system). After starting, the pressure will drop by up to 10psi. That's how it's designed, not a problem.

 

It doesn't start every time unless you spray it. I blew threw the filter and it came out completely clear. I'm new to this so I don't know how to test anything. The previous owner told me he thinks the fuel pump is getting weak or the sock is clogged. Plus the truck had no exhaust just headers and down pipe not cat. Could that cause it to spit and sputter wen you get onto it?

 

Follow the instructions in this thread and post all 4 readings: https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

Captain Hook's thread is a wealth of information, but the "How To" part isn't always obvious the first time you read it.

Here's a condensed (and slightly different) version:

1) Visually inspect the fuel lines from the tank to the filter and from the filter forward to the engine. Any kinks or bends or damage should be fixed first.

2) There's a "test port" or "service port" on the fuel line into the regulator/injector assembly, behind the throttle body, in front of the distributor cap (and slightly to the left, driver's side). It looks like a tire valve, and it might or might not have a plastic cap over it. That's where you hook up the diagnostic pressure gauge first. You can rent/borrow a pressure gauge set from many parts places. Autozone and Oreilly Auto Parts both have them in my small town. The kit is about $120, but you get all your money back when you return it. Connect the test gauge to the test port and watch it as you turn on the key. A second or two after you turn on the key (don't start it, just turn the key to the run position), the fuel pressure should come up when the pump primes. If nothing happens, you've got electrical problems with the fuel pump or fuel pump relay. The pressure should be 60-66 PSI on your 1996 Blazer 4.3L. This is the first reading you should report back.

3) Turn off the key, wait 10 minutes with the gauge attached, take another pressure reading after 10 minutes. This reading must be over 50 PSI. If it's lower, you have a leak somewhere. This is the second reading to report back here. If the gauge falls to zero immediately when the pump shuts off, you don't have to wait 10 minutes, just tell us that it fell quickly to zero.

4) Test the fuel pump maximum output pressure. To do this, you could buy the hardware listed in Captain Hook's "how to" discussion, or you could just find the fitting in the fuel pressure gauge test kit that hooks up to the fuel inlet line currently attached to the filter. Those diagnostic gauge kits come with a dozen or more little (mostly brass) widgets and doohickeys. There's one in there that looks just like the inlet side of your fuel filter. Using that, you can connect the gauge to the inlet pipe going into the fuel filter. Hook it up so the fuel pump is connected directly to the pressure gauge, and there's nothing connected to the fuel filter inlet. Turn the key on to prime the pump one time only while you watch the gauge. You might need an assistant to turn the key for you. The pressure will go up to show the maximum fuel pump output pressure. This should be well over 60psi, and could be as high as 100+ psi. This is the third pressure reading we're interested in.

5) Wait 10 minutes after testing the pump maximum output pressure, with the key off. Take another pressure reading after 10 minutes. This is the fourth pressure reading we're interested in. If the gauge falls to zero immediately when the pump shuts off, you don't have to wait 10 minutes, just tell us that it fell quickly to zero.

Knowing all 4 of those pressures, it's possible to make a much more specific diagnosis of where the problem is.

 

Holy crap racer, where did you get that? Adam, just listen to the Captain, he will get you going

 

There are only two differences between what I posted and the Captain's thread:

1. Captain Hook recommends connecting the gauge to the outlet of the fuel filter when testing the fuel pump max pressure. I generally connect as close to the fuel pump as possible, usually at the fuel filter inlet fitting.
2. Captain Hook recommends buying a bare gauge and assembling a bunch of parts, fittings and hoses to connect it to the fuel filter. I'd recommend "loaner tools" like this set from AutoZone or the fuel system pressure test set from Oreilly Auto Parts (it's a ways down the page, there isn't a direct link). Those kits include the fittings needed to attach to the fuel filter connection.

For the second point, I don't see the value for many home mechanics in buying an expensive diagnostic tool they only need to use once. I also question the accuracy and quality of some of the less expensive test sets. Better to use a "loaner set" that is (almost) a professional grade set.

For the first point, I don't believe in spending any effort "diagnosing" a fuel filter that is a maintenance part and is widely available for around $5. If the fuel filter is suspect, replace it. If it's a "new to you" used car, and you haven't replaced the fuel filter, assume it was neglected by the previous owner and replace it. If the fuel filter is over 3 years old or has been in service for over 30,000 miles, replace it because you should have already replaced it. If you have a receipt and can prove that it's new enough that it should be good, take it back, tell the parts source that it's defective and replace it.

 

Captain's instructions worked well for me. I know fuel filter's aren't expensive but I wouldn't but a $5 fuel filter. I got an ACDelco and it was around $15.