2005 Deville DTS Sometimes the car won't start unless I give it gas. Then when I let off it just dies. This will happen a few times, then it starts and idles normal. A few times it has stalled when i'm braking (no foot on gas). I think its the fuel pump. But at approx. $400-$500 i want to be sure. What else should I check first?
Intermittent problems are impossible to repair and even with the proper diagnostic equipment (hand held Tech II scanner), if it is an "at times" situation, the problem may not show up there.
You state you want to be "sure" as to the problem because of the cost of replacing the fuel pump and I truly understand this, what if I who cannot see what the car is doing tell you it is a fuel pump, you replace it, only to find that the problem is still there at times?
What the diagnostic equipment will tell you (only the larger service centers and dealers will have) if pressure is correct at the time it is being tested.
This could be an injection issue. In fact, it could be an electrical or electronic issue, a BCM (body control module-computer) problem an idle issue. There is no way of really knowing without the diagnoses when the problem occurs.
I would love to give you the answer you need, but it would be irresponsible of me or anyone on the web to give you the answer of your intermittent problem without being at the car with diagnostic equipment with the problem acting up. That is the only time you will get a "for sure" answer.
Working on a guess here can be very costly.
I understand the safety ramifications where depressing the brake and the engine stalling creates. Your description especially stalling while depressing on the brake does not sound to me like a fuel pump issue because there is a constant fuel supply with an electric fuel pump and I would expect it to be stalling driving down the road as well without depressing on the brake.
The problem with computerized cars is that if something is a problem, unlike carb equipped vehicles, computers will adjust for any number of issues and hide the underlying problem causing your intermittent symptoms.
It is possible that taking the car to someone with the proper diagnostic equipment now, might give you the answer you need, or you might have to wait for the time the problem becomes more frequent.
I would highly suggest you not start chasing ghosts and replacing a fuel pump on a guess.
Right now you have no answers and maybe you will if a tech II scanner is used.
At least, you have the potential of finding what might be giving you your symptoms and it is not a waste of money to have the diagnostic equipment used. If nothing shows up, you will have to wait until it becomes more constant, or if something does show up, you can have a guaranteed repair.
Bottom line-its too expensive to take a chance on replacing the wrong part.