How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tim's Auto Repair Your Own Question
Tim's Auto Repair
Tim's Auto Repair, Mechanic
Category: Car
Satisfied Customers: 16027
Experience:  Have owned a repair shop for 25 yrs.
Type Your Car Question Here...
Tim's Auto Repair is online now
A new question is answered every 9 seconds

1999 Pontiac Grand Am: Idles fine..backfires..Fuel pressure is 53psi

Customer Question

1999 Pontiac Grand Am. Idles fine, when giving it gas it bogs down and backfires. Fuel pressure is 53psi (engine off, key on), 50 psi at idle. Has good spark and new plugs. No SEL. Good compression at all cylinders (170 psi).
Submitted: 7 years ago.
Category: Car
Expert:  Tim's Auto Repair replied 7 years ago.


this sounds as if the ignition control module may be bad,,this is located under the zone and most parts stores can test this if you take it off and take it to them


Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.PLEASE ASK IF YOU NEED MORE HELP


Service and Repair




  1. Turn OFF the ignition.
  2. Disconnect all the electrical connectors at the ignition control module.
  3. Note position of spark plug wires for installation and disconnect the spark plug wires from ignition coils.
  4. Remove the screws securing coil assemblies to ignition control module.
  5. Disconnect the coils from ignition control module.
  6. Remove the fasteners securing ignition control module assembly to engine.
  7. Remove the ignition control module from the bracket.


  1. Install the ignition control module on the bracket.
  2. Install the coils to ignition control module.
  3. Reinstall the fasteners securing ignition control module assembly to engine.
  4. Reinstall the screws. Tighten Tighten the screws to 4-5 N.m (40 lb in) .
  5. Connect the spark plug wires as noted during removal.
  6. Connect the electrical connectors to the ignition control module.
Customer: replied 7 years ago.
Had ignition module tested at two different stores they both passed it. Replaced fuel filter and it know runs 56psi with key on engine off, jumps about 8psi with regulator vaccum hose removed. Pump seems to pressurize slower now and has slow leak down. Checked f.f. fittings to make sure no leaks--its good.
Expert:  Tim's Auto Repair replied 7 years ago.
does it run well at an idle?