Hello all,
There are parts everywhere and I am unsure of what is the best direction to go. I have more problems than knowledge and am in need of some answers and advise. I will try to tell the whole story as concise as possible.


98 blazer
4.3L Vin W
190,000 miles
Purchased 2 months ago


Initial symptoms:

• Would not start without turning the ignition on and of 4 – 5 times.

• Did not require extended cranking time. If it was going to start, it would start within 1 second.
• Once it started, it would run fine all day long.
• Cold or hot, you had to go through that procedure to get it to start.
• It would start right up with starting fluid.
• No codes.

Current symptoms:

• Will not start.
• It will start with starting fluid and will run for a few seconds then die.

Fuel pressure check:

• 50psi when you turn the key BUT.
• Pressure would drop to 0psi within ~ 15 seconds.
• Pressure almost instantly drops to 5psi then takes a few seconds to finish dropping to 0psi.
• You can hear a pretty noticeable hissing sound coming from the fuel tank. The hissing sound. lasts for about the same amount of time as it takes for the pressure gauge to return to 0psi.

Where I am now:

• Upper intake is off.
• Changed the fuel pressure regulator.

Questions:

1. Anyone have any ideas about this problem?
2. Is there anything in the fuel metering assembly that could cause these symptoms? I don't want to spend the $300 to replace it if I don't have to.
3. Why would the fuel pressure test drop to 0psi so fast? I was thinking that it should hold pressure.
4. What is the hissing sound from the fuel tank? Is this fuel returning to the tank?
5. Is there any way to check the old fuel pressure regulator?
6. Would a bad fuel pump cause these symptoms?

Sorry about the long post but I wanted to get the whole story out there. Any help will be greatly appreciated. Please feel free to ask any questions that may help resolve this problem.


Thanks,
Jeff

 

I think your fuel pump is going to turn out to be bad.It should hold pressure longer than that.The hissing in the tank could be from pressure and fuel back bleeding through the fuel pump into the tank.It still could be a intermitent problem.Find a area in the main feed line that has a rubber connection in it and power the fuel pump up,on.As soon as you do clamp/pinch the line and see if the gauge still drops or drops as fast,without cutting the line.It might tell you if that is whats happening.Fuel pumps can be really strange some times.my two cents Allan

 

Thanks Spyder1,
I finally decided to put it back together and just change the fuel pressure regulator. Got it finished and tried to start it. It tried to start. Cranked again...It stumbled and died. My helper put his hand over the air intake...I cranked it again...IT STARTED...Yeah...

So, I can get it started if I switch it on...off...on...off...on..crank..it starts. OR, restrict the air intake. I assume this creates enough vacuum to pull enough fuel to start even though the pump is flacky.

I will try to try your suggestion tomorrow. I was just worried that something in the fuel metering body was allowing the fuel to bypass and go back to the tank. I am not sure what causes the pressure to build to 60psi. I guess some things must remain a mystery...

Again, thanks for your help. I'll try to make it a point to post the results of the pump pressure test and pump replacement.

Jeff

 

second spyder1's notion. jerry

 

Chevrolet has a big problem with fuel pumps so replacing the pump would be ideal but you may want to check the wiring going to the pump as it is possible to have a break in the wiring somewhere. I did replace the pump in my 99 Blazer 4.3 with a Delphi,now if you use a Delphi pump most places will not warranty the pump if you do not use the new plug that it comes with

 

Have power to the fuel pump sometimes. It is a new pump and if I put power to it it runs fine. I have checked the relay under the hood and it is fine. Is there another relay under the hood?