Fuel Pressure and Pump in 96 Suburban

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Good Morning,

I have a few Question regarding my 96 Suburban. Its very hard to start, cranks over for awhile and most of the tiem will start but times it just kils the battery trying, It has spark so Im moving to the fuel system. Since it is throttle body how do you go about checking fuel pressure? There are a couple steel lines and one with a schrader valve but they actually go into the intake just behind the throttle body, are these the fuel lines? I cant see anythign else that may be them. Also is there any chance GM was smart enough to put an access in the floor to get to the fuel pump instead of dropping the tank, any help ASAP will be greatful I want to do this ASAP today.

Thanks
Chris

posted by  69396Chevy

There will be an access port with a schrader valve in the fuel rail. Fuel system tests are done in four phases.

1. Key On engine off (looking for proper fuel pump operation of clogged fuel filters, blocked return lines, etc.)
2 Key On engine On pressure should be about 5 -10 psig lower than step 1
3. Key on, engine on, vacume line to the fuel pressure regulator disconnected and pluged on the vacume source side pressure should be same as step 1
steps 2 and 3 are checking for correct fuel pressure regulator operation
4. Restore everything to normal, let car idle a couple of minutes the shut down engine and turn key off. System should hold pressure for several minutes (looking for leaks, leaky injectors, etc.)

A shop manual from either the factory or Haynes, Chilton, etc can provide you vechile specific specifications. pressures in step 1 and 3 should run between 45 and 60 psig depending on make of vehicle

posted by  tbaxleyjr

Ok so far this is what Ive replaced, needed it anyways.

Fuel filter, plugs, wires, cap rotor.

Checked fuel pressure when trying to start and it is between 40-50 psi, have also tried a new fuel pump relay. Holds fuel pressure when truck is shut off. I have yet to check the regulator since I wasnt sure how to do this, also I have checked the TPS and it is fine.

I can get it to start but it takes awhile, battery dies and I habe to hook the charger up. After it starts it runs great and will start again easily for awhile. But after sitting for a long time it wont restart. Worked on it more yesterday afternoon and it will not start again this morning.

A friend suggested the EGR, I was getting EGR Pintle Pos codes way before it started doing this and just put a new EGR valve on it. COudl it possibly a bad EGR valve?

Thanks

posted by  69396Chevy

Possibly.

IAC valves are known to clog with carbon as well

Is charging system working - most trouble shooting routines require fully charged battery thus it needs to be addressed

Have you put a scan tool on the car and if so, what are the trouble codes?

posted by  tbaxleyjr

No check engine light is on and no codes are in the computer. I havent checked the charging system since the engine cranks easily btu it was my next step, haev to get a friends tester from him. Also since the first post I have replaced the CPS which did not work either!

posted by  69396Chevy

Pressure should be about 55 to 60 try pressure regulator.

matt454   25 Jul 2012 01:54

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