90 backfires
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 2 of 2
HT4100 4.1, 4.5, 4.9 Discussion, 90 backfires in Cadillac Engine Technical Discussion; I purchased a 1990 Cadillac Sedan DEville about 3 years ago. It has 112,000 good condition except it doesnt drive. ...
  1. #1
    korbkill is offline Cadillac Owners Member
    Join Date
    Apr 2004
    Posts
    1

    90 backfires

    I purchased a 1990 Cadillac Sedan DEville about 3 years ago. It has 112,000 good condition except it doesnt drive. After about six months of having the car it started to chug then after about a month or so it started to backfire bad. On the highway i blew my muffler. Took it to a caddy dealership and they did not want anything to do with it. Took it to a family mechanic and spent a lot of time on it and nothing. Put about 1000 dollars in parts trying to fix my baby and now finally wont start it cranks but nada

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    BeelzeBob's Avatar
    BeelzeBob is offline I'm a Cadillac Fanatic!
    Join Date
    Dec 2002
    Location
    Fort Lauderdale, Florida
    Age
    50
    Posts
    9,577

    Re: 90 backfires

    Turn on the key, simultaneously press and hold the OFF and WARMER buttons on the climate control panel until the onboard diagnostics activates. Read off the trouble codes displayed and post back. First step.... Any sensor or electronic problems with the system will set codes in the system.


    You spent $1000 throwing parts at a non-running car without knowing why it won't run??? Wow. You need to find a new mechanic that knows what they are doing. Or someone that has the factory service manuals and can read. All the diagnostic trouble shooting diagrams to solve something like this are in the manual. Just follow them.

    Basically....it has to be fuel, spark or air. Without either the engine will not run. Assume for a minute that it has "air" as about the only thing there that could fail to cause the engine to not pump air would be the timing chain and that is bulletproof on that engine.

    Get a can of starting fluid (ether) and shoot some into the throttle body and try starting it. If the engine starts on the supplemental fuel from the ether then you can guess that you are looking for a fuel problem. Fuel pressure regulator, fuel pump, etc....???


    If nothing happens with the extra fuel then pull a spark plug wire or two off , put a dummy plug in the wire and ground it and crank the engine and see if it has spark. Easy check. Could be a number of things in the ignition system but if it has spark then you can rule it out.

    One quick check for "too much fuel" is to go to the fuel rail that surrounds the top of the engine and connects all the injectors. Find the small canister shaped device on the rail where the fuel return line exits from the rail. It will have a vacuum line on it. Pull the vacuum line off and have someone crank the engine while you watch the vacuum nipple on the FPR for any fuel leaking from it. Crank and watch for 20 seconds. If you see fuel from the vac nipple then the FPR is leaking internally and has to be replaced.

    Get a fuel pressure gauge (garage, auto parts store, rental..) and screw it onto the fitting on the rail. Check the fuel pressure while cranking.

    Lots of basic simple things to check that any mechanic should be able to do....

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting