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blazenxtreme

blazen ... 3/21/2010

2002 Chevrolet Blazer Xtreme 6 Cyl 4.3L

Engine

not enough fuel pressure?

I changed the fuel pump on my blazer, but still won't start I am only getting 30 psi at the schraeder valve

5 Answers


HouseCallAuto

HouseCallAuto 3/21/2010

When your fuel pressure guage climbs up to 30 psi does it hold steady at 30psi or does it drop off to -0- after the pump stops?

2002 Chevrolet Blazer 4.3L
Customer Concern:
Hard start Fuel pressure leaks off fast after the fuel pump stops running
Tests/Procedures:
1. Block the return line and see if pressure holds.

2. If fuel pressure still leaks down fast, replace the fuel pump sender assembly.
Potential Causes:
Fuel Pressure Regulator
Fuel Pump

Kevin - HouseCall Auto Mechanics

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blazenxtreme

blazenxtreme 3/21/2010

when the pump stops the pressure drops back to 0

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HouseCallAuto

HouseCallAuto 3/22/2010

If that is the same as you had before you changed the pump, you may have a leaking fuel pressure regulator inside the upper intake manifold plenum. If it is different then before (please explain) then I believe that you have a bad fuel pump. I will also guess that you replaced just the pump by itself without the rest of the assembly and that it was not an ACDELCO replacement but likely an aftermarket brand other than DELCO or DELPHI. I see big problems when you do not use the OE pumps in these GM trucks.

There is no easy way to isolate the pump from the rest of the system to conclusively condemn the pump. It has to hold pressure up at about 60 psi and if it drops to 0 the origin of that loss of pressure will be either the pump itself, the fuel pressure regulator, the injector stuck open (leaking injector) or a leaking fuel line (you would likely see that right away because of a visible fuel leak). Most times it is the pump.

Kevin - HouseCall Auto Mechanics

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blazenxtreme

blazenxtreme 3/22/2010

before we changed the pump it went to 45 psi and held

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HouseCallAuto

HouseCallAuto 3/22/2010

I would replace the pump assembly. I would only use an OE ACDELCO pump and I would replace the unit as an assembly only. Not cheap but the only way to keep it reliable.

Kevin - HouseCall Auto Mechanics

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HouseCallAuto

greasymoney 4/1/2010

Good advice Kevin! Also to be noted is that there is a huge difference between a pump for ported injection versus one for TBI, though they look identical. ( Was TBI still used in any models of that year?)

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