Question about Pontiac Grand Prix
i do believe you have to take the passengers side dash apart behind the glove compartment. go to autozone and get a manual or go to the library and check the chiltons manual. this is not an easy job. how bad is the leak? if its not bad these heater cores are made of all aluminum. i would buy a bottle of that radiator additive and see if that takes care of the problem first. it only cost about 5 bucks a bottle and it may permanantly fix your problem.
Posted on Aug 13, 2009
Hello! You're symptoms sound very much like a common problem associated with the fuel pump resistor. The GTP engine has a two speed fuel pump. There are two relays that control the fuel pump via the PCM module. The fuel pump relay and fuel pump hi-speed relay. Tied into the hi-speed relay is a fuel pump resistor that may go bad.
Symptoms vary but primarily the engine will start but die in a matter of seconds due to insufficient fuel pressure.
Here is a picture of the relay - which is located in the fuse box in the engine compartment:
What you can do to both diagnose this and either narrow it down to this or disqualify it as the culprit is remove relay #15, and bend out the tab labeled "85", and then reinstall the relay. If this does solve your problem, then you need to replace the Fuel Pump Resistor. Doing this will bypass the resistor, and place the fuel pump in "high" speed mode at all times. Once you have replaced the resistor, you need to bend the tab back to its normal position and replace the relay.
NOTE: while this may be a helpful diagnosis tool, and provide a temporary fix - doing this procedure for a prolonged period of time can lead to fuel pump failure. Use this at your own risk.
Hope this helps and good luck!
Posted on Sep 25, 2009
The thermostat housing is located in the upper radiator hose. You will see a metal elbow secured by two bolts into what I remember is the upper intake manifold...don't quote me on that but you will see it regardless of whatever I call it. Anyways, GM decided it was a good idea to put stainless steel bolts in there but that makes it easy to strip the threads in the bolt hole so I think it's best when you put your wrench on the bolt to just tap on the handle till you vibrate it loose, then turn it.
When you pull off the housing you'll lose a little coolant and it will create an air pocket which we'll address. It's a 50/50 chance that the thermostat housing gasket will either stick to the housing or the engine...it may be torn, cracked or flaking in either case clean both contact surfaces before you replace the gasket. I recommend an oil impregnated poly material gasket.
Note the position of the thermostat in the hole and place the new one in as such.
I recommend a 180 degree thermostat...stock is 195 but the GTP runs better with the 180.
Put on gasket and reinstall the hose/housing assembly, alternate from one bolt to the other so the housing mates flat and cannot cause a leak.
Next, fill the coolant overflow bottle to the "HOT" mark. If the bottle is dirty and hard to see just put a light on top of the bottle...GM didn't mark it very well so if it's not squeaky clean you can hardly see a damn thing.
*IMPORTANT** if your car still has Dexcool in it, DUMP IT. It will eventually destroy the motor.
If not...continue on. Start the car. Go back to the thermostat housing and place a rag on top of, and twist the peacock valve on top of it to let the air out until it starts to get coolant on the rag. Done.
Posted on Feb 27, 2010
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