425 not running
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500, 472, 425, 368 Discussion, 425 not running in Cadillac Engine Technical Discussion; Hi there, it's me again. It IS running, just stalling a lot.. Well, this is an old problem, but as ...
  1. #1
    arnauts's Avatar
    arnauts is offline Cadillac Owners Fanatic
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    425 not running

    Hi there, it's me again.
    It IS running, just stalling a lot..
    Well, this is an old problem, but as I've been driving my Fleetwood, I haven't had the need to address it at all~ But, as summer is comming, and the large car show in Langley called the Cruise In, where thousands of collector cars come from all around, I want to have it running well for this event.
    So, here it is. Two or three months ago, my 79 developed a problem; when you stepped on the gas pedal, it would stutter, and if you did not almost immediatly remove a bit of pressure, therefore giving it less gas, it would stall.
    At first I thought it was a clogged fuel filter, and so I changed it, with no effect.
    I assume it is some sort of fuel problem, where fuel is not getting to the carb when there is a higher demand for it, of maybe there is a impurity in the fuel tank. I have thought that it could be the fuel pump, or the carb, but as the carb was rebuilt only six months ago, and I tried a couple bottles of Carb Cleaner, I do not think that it is the problem.
    Is it possible that there is water in the fuel tank? As the problem became progressively worse, it went though serveral tanks, so it is not just the fuel.
    I'm kind of frustrated with it now, especially since I have some of the parts needed to do some major repairs.
    Thanks for your time,
    and you folks have a real good night now.

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  3. #2
    Benzilla's Avatar
    Benzilla is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    I had the same thing with mine, I went as far as to have the carb rebuilt... until I switched mechanics. Turns out it was just a bad vacuum hose.

    I'd start there.

  4. #3
    eldorado99's Avatar
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    Re: 425 not running

    Sounds to me like an accelerator pump, you could just replace that gasket on the pump or just rebuild the carb, if the accelerator pump is shot you probably need a carb rebuild anyway, that's what I would do, it's not too hard. Could be a vacuum leak as well like Ben suggested. I'll be at the Cruise-in in September as well, hopefully I'll see you there!

  5. #4
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    When I started working on cars in the 70's, the old timers used to have a saying: "A lot of carburators get rebuilt because of ignition problems". How old are the ignition components, plugs, wires,cap? Does it have decent power when you floor it? If so the fuel pump is probably ok. These cars are so easy to tune, I'll bet any mechanic over 45 would actually ENJOY working on a basic GM V8 for a change. The 425 specifies more initial timing than any engine I have ever seen; like 20 degrees or more. Do you suppose someone would have timed it without looking up the number? Is the vacuum advance working? A vacuum leak is very possible, but it would probably be idling quite high. I'm assuming the rebuilt carb was done correctly. You can check the accelerator pump by looking down the carb with engine off and twist the throttle. Good luck.

  6. #5
    arnauts's Avatar
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    Re: 425 not running

    Thanks kindly for the replys, and my appologies for the delay of the reply.
    I don't know much about carburators, besides their function, and a mild idea of their layout, let me say that right out. I have absolutely no idea where the accelerator pump would be located, so I've taken a handful of pictures that you folks can take a look at, and hopefully give me a better idea.

    As for the vacuum lines, all the lines around the carburator seem to be intact, and sealing tightly, except for a miniscule gouge on one of them of which I will post a picture.

    As for the ignition components, the plugs are 2 months old, and are Bosch +4 terminal plugs, which cost me a lot of money, and I believe they were changed two two weeks before that to NGK, and I just couldn't stand the thought of NGK sparkplugs, (they were the cheapest you could buy, and were put in by my 'mechanic') so I changed them. The plug wires are two months old also, and the age of the cap is unknown to me.

    As for it having decent power, I can *never* actully get the pedal all the way to the floor without it stalling. Before it decided to not move hardly at all, it used to hesitate from a dead stop, but do fine once the pedal was a bit farther down, but always sputter when it was floored.

    As for the timing, I had a incompetant mechanic keep the car for over a month just to get it to pass emissions tests.. he had the carb rebuilt, the cat/exhause tubing replaced, and pretty much replaced everything else in the engine that's easily replacable, and charged me a shitload of money. It was my greatest mistake thinking I could save on money by going to a backyard mechanic instead of a qualified shop. What do you mean by the vacuum advance?

    As for checking the accelerator pump, I looked down the carb, and put the throttle pushed the throttle back, and a bunch of gas flew into the carb, but after pushing it twice, verylittle came out, and them just air the following times. I have an archaic timing light around here somewhere, that I will hook up on the weekend and check the timing out, see if it's all in order.
    Again, thankyou all for your help.
    Regards,
    Jared

  7. #6
    arnauts's Avatar
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    Re: 425 not running

    Oops! Here's the pictures..






  8. #7
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    Re: 425 not running

    The vacuum advance is the part of your distributor that looks like a diaphram sticking out. It is connected to a vacuum hose that runs to your carb. This is the vacuum hose that you must disconnect from the distributor and plug it when you set your timing this weekend. I have seen people discussing a quick check of the vacuum advance on this board: With car off, disconnect the vacuum hose from the carb, and try to suck through it. If you can just suck air through it, it is ruptured and needs to be replaced. If you are met with some resistance, it is probably OK. I believe that what you saw when you looked down the carb and twisted the throttle was what you were supposed to see. Someone correct me if I'm wrong. The accelerator pump: When you look at the top of the carb, forward driver's side corner, the portion of the accelerator pump system that you can see is a lever that pushes down on a plunger when you twist the throttle. The throttle is directly connected to a rod that goes up when you open the throttle, the lever on the other side of the fulcrum goes down, pushes down on the plunger, and gas spurts out inside the primary carb bores. Just a little more background.

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    Re: 425 not running

    Accelerator pump lever is prominently featured in pic#3 upper right corner and pic#6 bottom right. In pic#3, the vacuum line coming out of the carb just below the accelerator pump lever (with a hose clamp on it) is probably running to the vacuum advance can on your distributor. And BTW, the one coming out the back of the carb, connecting to a metal vacuum line, I think is connected to your transmisision. Last time I checked all my vacuum hoses for leaks, I missed that one.

  10. #9
    Benzilla's Avatar
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    Re: 425 not running

    It shudders and feels like it will stall when you floor it? Mine did that too for a while after a horrible mechanic worked on it. All I can say is, your Phaeton has more than one problem. It's nothing big, but you need to take it to a mechanic who really knows his stuff. It's very easy and cheap to get these things running like champs if you know what you're doing. But you have to find the right person! my 425 throws me back in the seat now when I open the secondaries. It's a beast.

  11. #10
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    Yes, If you see gas squirting in the carb then the accelerator pump is fine. Does that choke open up when the car warms up? My town is full of good mechanics but I know in bigger cities it is very hard to find one. A lot of oil changers call themselves mechanics. On an outside shot, If you could find a mechanic that had a stock car or drag car in the yard, he could fix your car in 20 minutes. It's pretty rare for those HEI coils to go bad, but it could act like yours is acting. If that choke isn't opening,then the secondaries won't open, and you have no power. It could be the fuel pump too. It's something fairly simple but that carb looks fine to me. Good luck.

  12. #11
    gscott73 is offline Cadillac Owners Member
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    Re: 425 not running

    My 79 Sedan Deville is very finicky about ther choke position. Make sure that electric choke is doing its job. Go out first thing in the morning and watch. It should be almost closed but not quite at start up, and then slowly open up to full travel as the car warms up. These electric ones go haywire once in awhile. Sometimes there is no juice going to them, and thats very easy to test with a test lamp. Also, to time these beasts, you need a good tachometer. With the vacuum advance hose plugged, you want to set the timing to 23 degrees BTDC with the engine running at 1600 RPM. A lot of people set it at idle, and it really messes up the driveability of the car. Good luck, its not really that hard. I much prefer working on mine to the 91 Deville I also own that tends to be an engineering and electronic nightmare.

  13. #12
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    From the pics you've posted, it looks as if the carb has been replaced. The choke control vac motors look new also. Your vac hoses look new also. I had one 425 which ran real funky and I found that the vacuum line to the power brake booster was rotted back where the line ran below the throttle linkage and the cruise control cable.
    With a car this old, take a good look at your fuel supply lines. I've replaced these lines on two of my Coupes. Also check the fuel return line that runs from the pump and back to the tank running down the right frame rail.
    If you find you have to replace your fuel lines, concider replacing the brake lines also, because you'll find yourself under there replacing them sooner or later.

  14. #13
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    Red face Re: 425 not running

    Let me apologize in advance for this mess, and the time it took me to reply, I've been unfortunatly away from my car.

    Alright, so, first off, the vacuum hoses by the distributor, there is one that runs from a bulb shaped piece
    attached directly to the distributor, which is about three inches long; it is not attached to the carburator,
    but instead into a little pipe comming out of the intake manifold. The pipe that sticks out of the carb, featured here:

    runs about ten inches to under the distributor to a double hose fitting that looks something like this:
    ( Yeah, I know that this picture is mighty embarassing )

    and attaches to the one on the right side. the one on the left side runs to the to a T fitting, one of which goes
    to the condenser, and the other of which goes to the back of the carb, to that bulb shaped object, shown here:

    When I sucked on the hose comming out of the carb, i felt little resistance, and was able to suck air through it,
    So I replaced all the hoses shown in my diagram, made sure that they didn't leak, and I got no improvement.
    A couple questions though, the fitting that is under the distributor, looks like this:

    Since the folks at Lordco couldn't locate me a fitting like this, I just used two different hoses for the fittings,
    will this hurt anything? And I bypassed this thing:

    which was bolted to the intake, because I have no idea what it does, and was in a frustrated mood when I was replacing the
    hoses. Would this little device have any bearing on the running condition?
    The car still idles, but still will not drive more than five feet at a time. As for the choke, it seems to be operating correctly,
    nearly closed at the start, and then opening further as the engine warms. I am assuming that the carb was rebuilt correctly, and the
    vacuum advance is functioning correctly also.
    I have replaced every vacuum hose in sight, save for the fat one running out the front of the carb, which goes to the vapour canister,
    and thought I had it when I replaced a badly broken line, but still nothing.
    Like Al says, it's extremely difficult to find a decent mechanic in a large city, most of the kiddies over at the 10 minute oil
    change will call themselves mechanics. As for finding a stock car, most people around here drive shitty little imports that make
    80 hp or less
    Regarding the fuel pump, I can probably get one for about $40, right? I don't imagine it's hard to install, so it'd probably be a good
    place to start. Also, as I said before, the plugs, wires, and cap are only a few months old, but would it be worth looking into them?
    Also, is it possible that there's a buildup in the cyllinders, which is coating the plugs with a film that prevents them from firing
    correctly? I can check this after work tomorrow.

    I brought the old timing gun out today, which has been sitting around in the garage for apparently decades, and no surprise, it did not work.
    I suspect that the lightbulb is shot, which I will look into tomorrow. It may be worth while just buying a new one, as this one is from the
    early eighties.
    Taking a look at the power brake vacuum line, shoved way up above the fuse box, right out of reach, looks like I'm going to have a swell time
    inspecting.
    Tomorrow afternoon, I should get a chance to trace the fuel line under the car and back to inspect them for dents and restrictions.
    Again, I'm sorry that I didn't reply sooner, and I did my best to address everyone's suggestions.
    The two reasons that I dont' want to take it into a mechanic, are 1) there are no good mechanics around here, and the decent ones
    tell me that they dont' look at cars older than 1986 ...and reason# 2, I'm flat-ass busted.
    Best regards to everybody, have a good night.

  15. #14
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    I tend to agree that it must be the fuel pump. You are correct that they aren't too expensive and not too difficult to change. I had a carb problem driving me crazy a few years ago and it turned out to be the fuel pump so it sounds very logical to me.

  16. #15
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: 425 not running

    The gizmo that you bypassed is there to disable the EGR valve on a cold engine. It blocks vacuum to the valve when cold.

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