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help 95 blazer 4.3l fuel pressure problem

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Old 01-03-2012, 09:48 PM   #1
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help 95 blazer 4.3l fuel pressure problem

I need some help. I have a 95 Blazer 4.3l and it wont start. It starts with starter fluid but then die's. I hooked up a fuel pressure gauge and it goes to 62 psi then decreases to 30 and stays there. I replaced the Fuel pressure regulator, it was bad. put it all back together and still the same thing. I looked for leaks and gas draining out but nothing.

Is there some kind of relay or some thing or what is happening
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Old 01-03-2012, 11:00 PM   #2
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Re: help 95 blazer 4.3l fuel pressure problem

you need a fuel pump. my 94 did that right b4 it died.
Old 01-04-2012, 07:22 PM   #3
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Re: help 95 blazer 4.3l fuel pressure problem

sweet, I will look at the pump. Hopefully thats the problem.
Old 01-04-2012, 08:03 PM   #4
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Re: help 95 blazer 4.3l fuel pressure problem

Silly question but did you change the fuel filter?
Old 01-04-2012, 09:47 PM   #5
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Re: help 95 blazer 4.3l fuel pressure problem

It depends on where the pressures are at at which point of the starting I would say.

It should be right around 58psi while priming and running. It will drop some while cranking. How long does it take to go down to 30?
Old 01-05-2012, 10:36 AM   #6
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Re: help 95 blazer 4.3l fuel pressure problem

check the fuel filter first...
Old 01-06-2012, 05:32 PM   #7
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Re: help 95 blazer 4.3l fuel pressure problem

I change my fuel filter every 25K miles. If you have more than that, its time even if it isn't the problem.
Old 01-25-2012, 05:28 PM   #8
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Re: help 95 blazer 4.3l fuel pressure problem

The fuel filter is new, I checked the psi right before the fuel filter and it said around 75 - 80 psi, but doesn't decrease at all. Then I checked at the fuel psi check spot behind the manafold and it is saying around 50 then drops to 30 pretty fast. I have the manafold taken off right now and it looks dry but crudded up tho. I checked the voltage at the spider line connector and it is giving me .54 vdc is that correct or totally wrong? I have replaced the FPR, the old one was bad. But Now I am lost at what could be the problem.
Old 01-25-2012, 06:25 PM   #9
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Re: help 95 blazer 4.3l fuel pressure problem

Quote: Originally Posted by SBD-Spider
The fuel filter is new, I checked the psi right before the fuel filter and it said around 75 - 80 psi, but doesn't decrease at all. Then I checked at the fuel psi check spot behind the manafold and it is saying around 50 then drops to 30 pretty fast. I have the manafold taken off right now and it looks dry but crudded up tho. I checked the voltage at the spider line connector and it is giving me .54 vdc is that correct or totally wrong? I have replaced the FPR, the old one was bad. But Now I am lost at what could be the problem.
I went and tightened all i could and now it only decresses to 45 psi and stays there. Could the o rings be bad or could it be a pin preak leak that stops leaking at 45 psi?
Old 01-26-2012, 07:30 PM   #10
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Re: help 95 blazer 4.3l fuel pressure problem

I took off the fuel line that is going into the fuel injector spider line, It is giving me 75 - 80 psi. Is the spider line bad? I have replaced the FPR already, did I put it on wrong?



Old 01-26-2012, 11:08 PM   #11
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Re: help 95 blazer 4.3l fuel pressure problem

could be a bad new pressure regulator.
Old 01-29-2012, 03:58 AM   #12
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Re: help 95 blazer 4.3l fuel pressure problem

I have replaced the whole spider assy from one i got from a junk yard, it pushes to 60psi then in 2 sec drops to 55 psi and stays there. Then I replaced the FPR on that one and it still does the same thing, it hits 60 psi then drops to 55 in like 2 sec. WTF I am lost. I also put it all back together and spreyed starter fluid into the air intake and it started then blew a fire ball out it and almost got my face. I have never had some thing like that happen, What is wrong that it shot a fire ball at me lol.
Old 01-29-2012, 04:43 AM   #13
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Re: help 95 blazer 4.3l fuel pressure problem

That fuel pressure behavior is correct, the fireball is not!

If you get backfires/flames then most likely you have the firing order or plug wires wrong. It is firing a plug while an intake valve is still open.

Recheck the firing order on the cap.

Possible that you have valve problems, I'd check compression too. A burnt/sticking intake valve will let the combustion back into the intake.
Old 01-29-2012, 11:16 AM   #14
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Re: help 95 blazer 4.3l fuel pressure problem

I agree. It looks like you're getting there as the pressure looks normal now but the firing order sounds off. Go over everything again slowly, carefully...
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