Fuel Lines Quick Connect Fittings

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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Fuel Lines Quick Connect Fittings in Past Cadillac Vehicle Discussion; Hi. Just have a quick question. First, here is some background. My 92 Deville is experiencing horrible mlg, will do ...
  1. #1
    Piterrr is offline Cadillac Owners Member
    Automobile(s): 1992 De Ville Sedan
    Join Date
    Oct 2013

    Fuel Lines Quick Connect Fittings


    Just have a quick question. First, here is some background.

    My 92 Deville is experiencing horrible mlg, will do around 13 mi / gal.
    I noticed the block learn value would typically settle at about 112, while the integrator hovers at 100 counts. This is clear indication something is flooding the engine and/or there is a problem with spark.

    So I am doing my troubleshooting methodically, hooked up fuel pressure gage. Pressure holds fine, once I can get there (10+ sec of cranking required). When the engine is turned off, the gage immediately jumped to 0, like in a split second. Experience pointed me to the fuel pressure regulator because a leaking injector or check valve in the fuel pump would normally result in pressure dropping gradually (say 5 sec from 36 psi to 0). I took apart the regulator (out of interest - it's just me!) and discovered the spring was broken. (BTW, this was GP Sorensen branded fpr that lived only seven years, will not use them again). I put a different fpr and now things are somewhat better. It now takes "only" 2-3 secs of cranking before the engine fires, and once switched off, it takes roughly 5 secs for fuel pressure to drop to 0. So I know I am making progress. :-)

    Now the hard part. I am reasonably convinced the injectors are OK and not leaking. However, to do the power balance or pressure drop tests properly using the PCM diagnostic features, first I want to know if the check valve in the fuel pump is not the culprit. My plan is to remove the fuel filter and connect a male quick connect fitting with a threaded other end (q/c to AN adapter) which in turn will screw onto my pressure gauge.

    The question: Does any1 know (1) what size the fuel filter quick connect is (3/8, 5/16, etc) and (2) what AN thread (-5, -6, not an AN?) the fuel rail test port has (because that's the thread the fuel pressure gage mates to)?

    I want to get an adapter, such as this

    If I could use these fittings, that's much cheaper than buying Kent Moore tools.
    BTW, if it's any easier, K-M J-37287-2 is mentioned in the FSM, if some1 knows what size the male quick connect is on the tool, this would kill (1) above.

    Sorry about the lengthy post, but I like to give people background so they understand where I am coming from.

    Many thanks!


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  3. #2
    Piterrr is offline Cadillac Owners Member
    Automobile(s): 1992 De Ville Sedan
    Join Date
    Oct 2013
    Thread Starter

    Re: Fuel Lines Quick Connect Fittings

    Hi again.
    I'm disappointed that no1 had an answer for me. A bit frustrated, I went to a local NAPA outfit for help. They didn't have anything along the lines of what I wanted but these folks have tremendous industry knowledge. They knew what I needed, the fitting size and thread sizes. They sent me to a belt and hose outfit literally half a mile away and said these people would help me. I went there, presented my problem, and they said "no problem". I had the adapter custom made right there! While not exactly cheap, it still cost me less than what I would pay for a combination of adapters, or a Kent Moore tool.

    Here is what I got.


    In case any1 else needs to know, GM quick connect fittings are 3/8" and the fuel rail pressure test port has AN4 thread.


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