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Fuel pressure dropping

L

Linebacker

New member
Hey so i have a 2005 Pontiac Grand Prix gtp comp-g and ive been having some hard starts lately and i have ruled out all the ordinary causes.

I picked up a fuel pressure tester and hooked it up and noticed that when i prime the pump by turning the key to the on position the pressure jumps to about 57-59 and than will start leaking down immediately. My fuel pressure is close to 0 after only 5-10 min.. I can think of two issues.

Either my fuel pressure regulator which i understand to be apart of the fuel pump is bad.... Or i have a leaking fuel injector. I was thinking of switching out all my fuel injectors since they are all stock and my car has just over 125000 miles on it. Does this seem like the right course of action?
 


You can rule that out pretty easily by pulling the fuel rail, then priming the pump to see if any are leaking. Regulator, just pull the vac line and see if there's fuel in there. If not, probably pump. My suburban did the same thing before the pump died, I'd have to prime it a few times before cranking to get it to start, otherwise it'd take 5 seconds or so of cranking.
 
When it hard starts, is it just a like a stumble then stall type of start. Like it runs for maybe 1 second and dies just away.

Have you ever cleaned the throttle body?? Because that is the 04+'s biggest issue for hard starts.


I wouldnt buy new injectors at that mileage, they arent known for going bad unless one is just pissing fuel out all the time.
 
Yes i did all the routine things first... MAF,TB,Plugs, Fuel injector cleaner, Air filter... all of that is done twice a year other than the plugs.

It will stumble for a few seconds some mornings and than fire perfectly the next try... after that it will start fine all day.

Can you explain what you mean by pulling the fuel rail? Also which VAC line?

I have replaced about 5 fuel pumps and although ive never had issues doing them i do dread laying on my back with gas for 6 hours.. how hard is it to replace on this car?
 
2004+ have a return-less style fuel system, there is no vacuum line on the regulator like a 95-03 motor.

If you are lucky the access panel is under the carpet in the trunk, it was removed sometime through the 2005 model year for whatever reason. 2005.5-2008 do not have the access panel and the tank would need to be dropped, unless you want to cut a hole in the trunk.
 
Damn '04+ with its weird fuel system and dbw. By remove the fuel rail, I mean take the fuel rail off the engine with the line attached, set it up on some cardboard or something, then turn the key forward to pressurize the rail and see if any of the injectors are leaking fuel. On the '97-03 there's 4 nuts, and 1 stud on top of the blower holding it on, not sure about yours but it should be similar.

Or just replace the pump, that's probably what's bad
 


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