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Discussion Starter #1
I need some help please. I own a 1995 StS and this morning it wouldnt start. When it did finally start, it allmost stalled then leveled off but was idling rough at idle. I replaced the plugs, wires, coil pack. I checked for codes but nothing. If anybody has had a problem like this before please post reply. thanks
 

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Here's what I would do;

1. First check for a leaking FPR. If its good proceed to # 2

2. Find out what cylenders are not firing. There are two ways to do this. One way is to unplug each spark plug wire one by one (engine running), plugging them back in as you go, to find the one(s) that has the least change in how the engine is running.

The other way is to disable each fuel injector one by one through diagnostics mode with the engine running. To do it that way you enter diagnostics mode, and when it says "PCM?" you press the fan up button. Then press the fan down button untill you reach "PCM OVERRIDE?", press the fan up button to enter that menu. Then press the fan down button again until you reach "PS04". Leave that on the big LCD screen and press the cooler button (blue) and hold it down to disable the cylender#1 injector, then press the warmer button (red) to select the next injector and press the cooler button to disable that one (you should see what # injector you're on in the climate control LCD). Repeat this until you've gone through all 8 injectors and have noted which ones give the least effect on how the engine is running. Once you know what cylenders are missing move on to #3

3. Pull out the spark plugs in the cylenders that are missing. If they are wet with gas, you know the problem is most likely electrical (move on to #4) . If they are completely dry, and don't even smell like gas, its most likely a fuel related problem (move on to #5).

4. Follow the wires and see if the cylenders that are missing are being run off the same coil pack. If so, the coil pack is no good. If not, you have some bad spark plug wire connections (not snapped on all the way). Anything before the coil, the PCM would sense and throw a code. It could also be a bad EGR valve.

5. Change your fuel filter and see if that does the trick.


My god, I could go on all night, but I think I said enough to get you started. lol.

Hope this helps.
 

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Discussion Starter #3
thanks alot for the info, I know this is gonna sound stupid, where is the fpr on the caddy. I just bought the car 6 months ago my last car was still haD A CARB AND NO PCM.
 

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It's under the beauty cover, attached to the fuel rail, and it has a vacuum hose going into it. If you turn the key to the "ON" position (do not turn the engine on) it should pressurize the fuel system and if you see gas come out of the nipple that the vacuum hose is attached to (remove the vacuum hose to see), the FPR is bad.
 

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Discussion Starter #5
Thanks krashed, I'll try that in the morning and let you know. I was talking with my boss and he's got me worried. He told me about his GTP, same sounding problems as my STS and his ended up being a fuel pump. He did the same as me thinking it just needed a tune up ( wires, PLugs, fuel filter, air filter, injectors cleaned). The pump for the GTP costed him about $800. So if my STS needs a pump how bad do you think a STS fuel pump could cost?

Maybe my boss just wants me to work more OT or jealous that I got a nicer car than him:histeric:
 

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My Caddy had that too, with me, the battery wasn't hold that great of a charge and their were alot of cylinder misfires. I had it pressure tested at a Caddy dealership and.... it was.... bad head gaskets. I hope that's not what it is for you, your car and you will be in my prayers tonight.
 

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Discussion Starter #7
Thanks Mac, I hope its not that either but the oil isn't milky and no smoke out the back. The temp is normal all the time. The car holds a good charge and runs great. It's just at idle it seems a little rough and a couple of times it didn't want to start rite away. I started looking for prices on a fuel pump ( just incase) but AcDelco doesnt even list 1 for my car.
 

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When mine was bad, I would start it, it would feel like it wanted to die, the rpms would go up to about 2500, shake like a son of a gun, and I could smell anti freeze out the tailpipes. If I pushed on the gas a little bit, the shaking would pass by in about 30 seconds or so, if not, it would last for a minute or two. Not that I want your car to be malfunctioning in any way but I'd like to see it be something small as I'm sure you do too. Let us know what happens as you find out. Good luck again.
 

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Also, does your oil have bubbles on the dipstick when you take it out, check quick when you take it out, if it does, it's water in there. Also, make sure you check your coolant often to make sure that it's where it should be. In mine, the coolant was going through the head gasket into the oil. Keep an eye on all of it.
 

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Due to the design of the Northstar we have been told that it will not get coolant in the oil from a bad gasket.

Get a fuel pressure guage on the schreader valve (on the fuel rail). Turn the key on and see what kind of fuel pressure you have. It should be 45-50 psi I believe.
 

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Discussion Starter #11
Will do Ranger, I'll be working on it on Friday and post the results. And thanks to everyone for thier help. great site:thumbsup:
 

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Ranger said:
Due to the design of the Northstar we have been told that it will not get coolant in the oil from a bad gasket.
... so we've been told. I'm trying to think if it was the oil or not, I know that I could definetly smell it coming out of the exhaust.
 

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coppertop said:
Thanks krashed, I'll try that in the morning and let you know. I was talking with my boss and he's got me worried. He told me about his GTP, same sounding problems as my STS and his ended up being a fuel pump. He did the same as me thinking it just needed a tune up ( wires, PLugs, fuel filter, air filter, injectors cleaned). The pump for the GTP costed him about $800. So if my STS needs a pump how bad do you think a STS fuel pump could cost?

Maybe my boss just wants me to work more OT or jealous that I got a nicer car than him:histeric:

A good indicator that it's not a fuel pump issue is if you can rev the engine without it stalling out on you.
 

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Discussion Starter #14
Krashed989 said:
A good indicator that it's not a fuel pump issue is if you can rev the engine without it stalling out on you.
I dont think its the pump either now. Tonight I got in the car to get work and again it wouldn't start. All it would do is crank over, I just touched the gas and boom fired rite up. Friday it will be getting a new Fuel fiter, Injection flush(#4 cylinder looked a little lean when I pulled the plugs out today) and checking and replacing FPR if needed. What i wanted to ask you to check FPR. Vacum line off and key to on but motor not running? I was reading in another post on this site to check it car is be to running. Just wanted to make sure.:hmm:
 

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On a '95+ it makes no difference. Either way, the fuel system is pressurized. '93 & '94 are the ones that have the FPR inside the manifold and the engine MUST NOT be started. Key on only on those engines.
 

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Discussion Starter #16
Well I had some time today and checked the FPR, I didnt see ant gas drip out of the nipple with key on or started but I did smell gas on my fingers from when I removed the vacume line. Well the car will be going to a shop tommow to get an injection flush, fuel filter and oil change. Do you guys still think it could be FPR from the smell of gas from my fingers?:confused:
 

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coppertop said:
Well I had some time today and checked the FPR, I didnt see ant gas drip out of the nipple with key on or started but I did smell gas on my fingers from when I removed the vacume line. Well the car will be going to a shop tommow to get an injection flush, fuel filter and oil change. Do you guys still think it could be FPR from the smell of gas from my fingers?:confused:
If there was any gas near the vacuum nipple on the FPR, it is bad. There should be zero gas there. You might have to use a small handheld vacuum pump to see if it will hold a vacuum to really prove it. If you put a small vacuum on it and it fills the thing with gas, the FPR is bad.
 

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coppertop said:
Well I had some time today and checked the FPR, I didnt see ant gas drip out of the nipple with key on or started but I did smell gas on my fingers from when I removed the vacume line. Well the car will be going to a shop tommow to get an injection flush, fuel filter and oil change. Do you guys still think it could be FPR from the smell of gas from my fingers?
That was my story. I could only smell fuel - no visible signs. Eventually it started leaking.
 

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Discussion Starter #19
Thank again guys:D I guess I'll add a FPR to the job tommow. It was just driving me crazy for the last little while. I just want my baby to run the way it should, LIKE A CADILLAC.
 

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coppertop said:
Thank again guys:D I guess I'll add a FPR to the job tommow. It was just driving me crazy for the last little while. I just want my baby to run the way it should, LIKE A CADILLAC.
If you're paying someone else to do it, tell them to skip the injection service and fuel filter and just do the FPR and oil change. That will likely fix you up for the lowest cost.
 
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