97 Blazer Won't Start

I have been fighting this problem for over a week. So here is what I have as of today.

4.3L Vortex

Engine cranks over but will not fire.

Ignition module Tested Good!
New Distributor Cap & Rotor.
Getting spark to plugs.
New Fuel Filter.

Here is the kicker.

I pour gas down the throttle body and it will start right up and run, most of the time on the first try, a few times had to do it 2 times before it would stay running.
Once started it runs fine, took it out today for about 15 miles, on the highway and town it ran fine.
I bring it home shut it off for a couple minutes and try to start it, starts ok. Leave it sit for a while and NOTHING just cranks.

Now I have read alot of the posts here about the 97 Blazer, I don't claim to be an expert mechanic but I beleve I have narrowed it down to a fuel pressure regulator or fuel pump.

I don't have a fuel pressure gauge to test the pressure. But I did notice when I went to relieve the pressure before I changed the filter there was very little pressure.

Any help would be apreciated.
Thanks

Test the fuel pressure.

do you hear the pump running for a few seconds when the key is turned on? if not the pump relay or wiring might be bad. but either way a fuel pressure test is a good start. if the pump does run when the key is on try cycling the key 5 or 6 times before cranking it over.

i just went through the exact same drill with my 97 blazer and i found out i needed a fuel pump.(you need 60-68 Lbs pressure) have yours pressure tested first as pumps are very pricey mine was $320 after a discount some parts stores were over 400 so it pays to do your homework if it is the pump
also dont forget the filter while your under there
good luck
Urickmic

I am having an identical problem with my Jimmy ('96). If it was the fuel pump, why would the car stay running once it starts?

I am having an identical problem with my Jimmy ('96). If it was the fuel pump, why would the car stay running once it starts?

Exactly my Question, It should act up at some point but mine does not.

Exactly my Question, It should act up at some point but mine does not.

get a fuel pressure gauge and see what the psi is with the key on, engine not running (when it won't start). Mine is around 40-45 psi, and it takes forever to get it running when it is like that. Once it starts (with the help of starting fluid) it goes to 55psi or so.

The local dealer says its the fuel pressure regulator, which is about $75 in parts and 2 hours to fix. I'm planning on checking the battery first per Blazer LT's suggestion, but I don't have a DVM, so I'm going to have to borrow one. I could also just swap the battery from my Blazer which is working fine.

I really don't think its the battery, since is spins over the engine very well and all the other electrical stuff is fine, but that is easier than swapping the fuel pressure regulator.

You need to check your fuel pressure with the key on and the engine not running. It should be a minimum of 55-61 psi (it should be more for trouble free operation). If it is check your battery.

For those of you who are asking why it works after you use starting fluid.

Read this it is taken from an article about CSFI:

From a service standpoint, however, this system has its weaknesses. There are two problems that have ended up being pattern failures. First, the system runs at higher fuel pressure than what we are accustomed to seeing, 56-64 psi. The poppet injectors will not open reliably with much less than 54 psi. I believe it was the Vortec cold hard start problem that was the inspiration for the concept of checking fuel pump rpm by means of the low current probe and the lab scope. The problem occurs during cold mornings when battery voltage is not what it might be. During cranking, voltage to the fuel pump drops. The rpm and consequently the pressure of the pump goes below the level necessary to open the poppet valves. Some of these hard starters took months to diagnose because a tow truck driver would hook up his jumper, and voltage would rise high enough to gain the extra two or three pounds of fuel pressure. Or, the vehicle would be towed in during the cold morning, but by the time the shop got around to checking the vehicle, the ambient temperature had warmed enough to kick up battery voltage, and the thing would start. Techs who were in the habit of not looking stuff up would see over 50 psi on their gauges, and, of course, that had to be enough! Sharp guys like Jeff Bach (current probe guru) and Jim Linder (the injector guru) learned how to scope the fuel pump waveform with the lab scope and calculate pump condition and rpm, almost to the point of being able to predict what day of the year the vehicle would fail to start!

I read that article and Its great. The problem in my case is that the fuel pressure doesn't get any higher even with a running vehicle connected to the battery with the biggest jumper cables you can buy. If a fuel pump is bad (completely) it will not pump any fuel regardless of whether or not you get the engine to start with ether or by pouring fuel into the intake.

There is no reason that I can think of that a car will have more fuel pressure when running than when not unless the fuel pressure regulator is bad.

Of course, I could be abnormally stupid.

With the engine not running a normal battery has 12.5-13 volts. When the engine is running it has over 14 volts. This will increase the output of the pump even if it is going bad.

I'm not saying that the battery is the problem, I have read in alot of posts that people have replaced the pumps and had no more problems. I believe this is probably from a combination of a pump operating below par and the low voltage at start-up.

you keep forgetting that your going to have 14 plus volts at startup from the running booster vehicle.

It didn't make ANY difference.

does the fuel pressure regulator use vaccuum to control the fuel pressure?

you keep forgetting that your going to have 14 plus volts at startup from the running booster vehicle.

It didn't make ANY difference.

does the fuel pressure regulator use vaccuum to control the fuel pressure?

I didn't read that you checked the pressure with the other vehicle connected and running.

Yes the regulator uses vacuum to control the fuel pressure. But it is suppose to reduce the fuel pressure with the engine running. When the engine starts it applys vacuum to the regulator, the more vacuum the less fuel pressure. That is why it is suppose to drop 3 - 10 psi when the engine starts.

I didn't read that you checked the pressure with the other vehicle connected and running.

Yes the regulator uses vacuum to control the fuel pressure. But it is suppose to reduce the fuel pressure with the engine running. When the engine starts it applys vacuum to the regulator, the more vacuum the less fuel pressure. That is why it is suppose to drop 3 - 10 psi when the engine starts.

could a bad regulator increase the fuel pressure when the engine is running?

I am having problems with my 95 Astro 4.3 CPI.

I changed the CPI, nut kit, and fuel pump and the pressure drops from 62psi to 20psi with the key off.

Any ideas?

Sounds like the check valve in the sending unit is stuck open.

That or you got a defective injector.

BlazerLT, what would you say would be the symptoms of a bad fuel pressure regulator?

Fuel pressure not holding on starup.