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1990 Deville
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4 Posts
Discussion Starter #1
I have a caddy that won't keep running. It will start with a shot of starting fluid but quits running when that is used up. I drove it into the garage and turned it off so it was running then. I drove it into the garage because of an exhaust problem. I lost that little tube coming off of the catalytic converter in the snow and ice from our last snow storm (Minnesota). I have a new catalytic converter installed but have not connected that small tube to the air pump. (I think that is where the line is supposed to go.) Is it possible this missing line is preventing the engine from running? I don't think it would cause a vacuum leak but I am not sure. Any ideas? I used my code reader on it and it didn't show any trouble codes. Gas tank is full. I just filled it a couple weeks ago.
 

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1993 Coupe Deville, 2009 XLR-V 1 of 6 Crystal Red
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2,484 Posts
You don't need a code reader, all of your diagnostics are on board. Read the sticky at the top of the page on how to pull codes. Write them down with a definition of the codes and post back. This sounds like you have a fuel problem, I'd start by taking a pressure test.
 

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1990 Deville
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4 Posts
Discussion Starter #3
As I stated, there are no trouble codes. Using the climate control buttons or a code reader does the same thing. I agree I have a fuel problem. Do you know how to test the in-tank fuel pump so I could rule that out? What I mean is, is there a way to do it without going out and buying a fuel pressure tester?
 

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1993 Coupe Deville, 2009 XLR-V 1 of 6 Crystal Red
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2,484 Posts
Oh I'm sorry, guess I missed that on your not having codes. I wonder if the parts store where you are have a pressure gauge they'll loan? Your test port is on the fuel rail, or does your year have a TBI, I can't remember on the 1990. If you test it past the fuel filter, that will at least tell the tale up to your engine where you really need the pressure. What you could do is take the line loose up at your engine and turn the key on for a second or two, should get some gas coming out at least you would know if the pump was getting gas up there. Can you hear it running when you turn the key on?
 

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1990 Deville
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4 Posts
Discussion Starter #6
There is no fuel pump pressure. I pushed the fuel pressure release valve and only got a small drop of fuel. Does anyone know where the fuel pump relay is located on this?
 

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1990 Deville
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4 Posts
Discussion Starter #7
I replaced the fuel pump relay and the fuel filter so it looks like I will have to replace the pump. Thanks all.
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
Remember the fuel pump does not run on its own until the engine has oil pressure. When you first turn the ignition key to run, The fuel pump runs for a second or two to pre charge the fuel injectors and then shuts off. It then turns back on during engine cranking. If you try to check the pump by leaving the key on, You may think the pump is bad. Does the pump relay click on for a second or two at startup? Is there power getting to the pump when started? Is the pump fuse ok? (on the relay panel by the pump relay) Is the ground good? Is the oil pressure switch functioning properly? There are two circuits on the switch. One for the oil light and the other for the fuel pump. (safety feature so fuel doesn't spray all over your engine in the event of a collision) You have to remove the tank to replace the pump so a little checking can save you some time.

That said it does sound like you have a bad pump!
 

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1990 deville 4.5 MPFI V8
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2 Posts
it should be more than a small drop , but pressing on the presta relief will only relieve the pressure in the fuel line, not completely drain the rails , or draw more gasoline from the tank. it is not supposed to come gushing out when the car is not running. a gauge is < 15$

you will hear the fuel pump make a high pitch whirling noise when you turn the car on, if not, def electrical or pump. if heard could still be faulty pump.

BTW, I'm not sure about the vacuum, but probably yes and if so that hose from the catalytic converter could be causing you to loose enough pressure to effect the FPR?? IDK just a thought, may not be your problem, but i would fix it just to make certain and for milage and performance when she does fire up. REPLACE THE HOSE
 
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