This is a non SC 3800 that gave me erratic startup problems where it would sometimes start up quick but other times after short trips would sometimes crank a lot before starting. So I replaced the fuel pressure regulator since the stock one was leaking fuel into the vaccum line. Now I get a hard start everytime unless I prime the car twice with the key switch. I just bought a fuel pressure gage that shows the fuel pressure quickly dropping after a prime with the key switch. (There is no fuel leaks)
My question is, will adjusting the regulator with a torx. wrench on the screw on top of the new regulator get the fuel system to hold pressure. Or is there something wrong with the fuel pump.
Well, I swapped the regulator and I still have the problem. Do I need to adjust the tamperproof torx nut on the top of the regulator or is this a fuel pump problem? Doesn't the fuel pressure regulator hold the pressure while the car is off for a while. Or is there some kind of check valve at the fuel pump that holds the pressure?
I bought a delphi regulator through Napa. I talked to a Gm mechanic and he told me it could be leaking past the o-rings on the regulator or a leaking injector. I lightly oiled the o-rings and put the regulator back in. Same problem. Then I pulled the fuel rail out with the injectors and pressurized the line. No injectors leaked. So it looks like it could be the check valve at the fuel pump. Is the regulator designed to hold pressure in the line when the fuel pump isn't pumping?
The mechanic that I talked to didn't seem to think there was a check valve at the pump even though I kept asking about it.
Car car starts better than it did before I replaced the regulator. It's just that sometimes it might take a 1 sec. of cranking which seems like a long time when most of the time it is instant.
I'm just curious because my fuel pressure gage shows that in about 10 sec. the line pressure drops to zero (Priming lines without turning on the engine)
Maybe there isn't a problem.
Thanks for the responses so far.
Losing all fuel pressure in 10 seconds at key off is most certainly a problem.
Regulator is designed to make it hold pressure at key off. You swapped the regulator and that didn't fix it.
You say you checked for leaky injectors by pulling the rail, and found none.
You say you see no fuel leaks in the lines; did you check the lines all the way back to the tank? (Especially at the connectors at the filter and from the sender unit?)
I think you've pretty much eliminated it down to either a leaky fuel line / connector near the filter or tank (though I think you'd smell that and see puddles), or more likely a bad check valve in the pump (yes, the pump does have a check valve).
Thanks for the response. I just wanted to be sure that the fuel pump had a check valve before I went in there.
Now I just have to come up with the money to buy a fuel pump.
One thing to keep in mind when looking at the cost of a pump is that you can remove the pump from the assembly. GM won't ever mention that, but you can and then replace only the pump.
Thanks for the tip. So far, the cheapest I have found was a delphi assembly for $258 from Rock Auto. I'll have to see what just the pump costs. Of course the valve may be part of the assembly and not the pump. Anybody know for sure?
The check valve is part of the pump. It is a much neater install to change the whole module but easier on the pocket to change the pump. You can find the correct pump by clicking on the intense or wbs link on the left of the page.
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