car is 2002 grand prix, 3.1
While driving (problem just started) the car is starting skip a beat or cut out, most noticeably at 3000 rpm- feels like the transmission skipping a gear but I do not believe it is the tranny-
When in park and revving the engine, motor will get a rhythmic miss.
No codes have been set.
How do I test for fuel pump failure and what other causes might I look for?
Thank you.
I would think it would be more likely a spark issue.
To test the pump, you need a pressure meter and and you need to measure the volume pumped over a given time. You will need the specifications for your car, but I can’t help you there.
What is the maintenance history? Is it due for spark plugs and or wires? How about air and fuel cleaners? Any other maintenance items not up to date?maintenance- plugs are less than 30k old, air filter new- not sure on the fuel filter so it sure wont hurt to change it-
One thing about the spark plugs is that the ‘miss’ is not constant- When I revved eng previously I got a rhythmic bump, bump, bump at high rpm- now it does not repete that while revving- the problem was sudden while driving, mostly while getting up to speed from a stop, and then just a jolt or two- I was thinking a bad plug would be more constant- I will change the fuel filter though and see what happens-
Thank you for the information.
just changed the fuel filter- no change in problem-
You should ask yourself why no codes are being set,by your description it sounds like you qualify.
I don’t really know what all systems the codes cover, if a fuel system problem is even covered by the codes- all I have is a code reader and a book to interpet the codes-
Feels to me like the eng is starved for fuel when I maintain a high rev (parked) and like the car shuts off for a second when driving - tach drops and recovers when this happens.
A trouble shooting cflow hart would be a help-
You will not see fuel system codes like “change fuel pump it is bad” thats not how things work. What is expected for your car to spit out are “random misfire” “multiple misfire” or misfires with the cylinder that is affected identified.
The fuel system angle comes in when we get into identifying why we are having these misfires (ignition,lean conditions,mechanical conditions) you must use the code to get a direction as to what is causing the code to be generated.
Like why is my car “skipping” check code,OH misfire detected cylinder 5,now start looking for the cause of the misfire.
The problem is there are no codes being set to give any direction.
I appreciate everyones replys and help- I’m going to sleep on it now and start over in the morning.
Thanks again.
You say, “…feels fuel starved to me.” Ok, check out the fuel pressure. You want to check the fuel pressure at higher rpm, and with the engine under load. A check, only at idle, isn’t sufficient.
Attach fuel pressure test gauge. Put the test gauge where you can see it from the driver’s seat (or, employ a “lackey”). Put foot firmly on the brake pedal, put the automatic transmission into DRIVE, increase the speed to 2,000 rpm and hold it there for three minuets. Monitor the fuel pressure. If the fuel pressure holds to specs with the engine under load, move to ignition diagnosis.
I will give the fuel pressure check a go today-
Just thinking if I was having an electrical misfire, I should be getting a trouble code setting.
Thank you for the advise.