Cadillac Jim Posted November 5, 2008 Report Share Posted November 5, 2008 I can understand why the fuel pressure might go to 10 psi when the key is turned on because the fuel pump runs for a few seconds to start the car. Going to 30 psi after the car starts also is consistent, because once the oil light goes out the fuel pump runs continuously. However, 30 psi is out-of-spec. The fact that it didn't go to 45 psi says that the fuel pump is probably bad. P0151 Heated Oxygen Sensor (HO2S) Circuit Low Voltage Bank 2 Sensor 1 P0171 Fuel Trim System Lean Bank 1 P0174 Fuel Trim System Lean Bank 2 P1599 Engine Stall or Near Stall Detected I vote with JimD. I would save my FPR money unless it has a leak or other visible fault. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
Ranger Posted November 6, 2008 Report Share Posted November 6, 2008 I remember the Guru saying that the fuel pump will pump the system to 45-50 psi almost immediately. I'd say you are in the fuel pump business. Link to comment Share on other sites More sharing options...
PAUL T Posted November 6, 2008 Author Report Share Posted November 6, 2008 O.K. guys, I broke down and ordered the fuel pump from Rockauto today so I hope it will be here by the first of the week. The way I was thinking, the problem with the stumbling after fill up was due to the fuel level in the tank being high enough to short the pump wires out. Am I thinking right or way off base here? I saved the FPR money for now. I just hope the fuel pump takes care of the lean codes and lower mpg also. The O2 sensor should be here soon anyway. So I plan on putting it in also. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted November 6, 2008 Report Share Posted November 6, 2008 Fuel is not a conductor, and in any case your in-tank equipment is designed to keep things going in case there is condensation or water in the gas. When you drain the tank to change the fuel pump, put some in a glass jar and let it sit with a tight lid overnight. In the morning, see if any water settles to the bottom. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
PAUL T Posted November 26, 2008 Author Report Share Posted November 26, 2008 Update - I changed the front oxygen sensor but I got a P0174 while idling in traffic today. I checked the vacuum lines again and no leaks. I think I will check the injectors to see if they are seated good next. I have not installed the fuel pump yet due to the weather being bad and my garage being cluttered. Another thing I have noticed is that the engine will not run good after the car has been sitting on an incline with the front of the car up. If the front is down it is fine. Fuel pressure is still 30#'s and still hard starting. I am also leary of a vacuum leak though but I just can not find one. The codes are not constant just intermittent. I may try a new pcv valve to see if it is sticking. Link to comment Share on other sites More sharing options...
alwing17 Posted November 29, 2008 Report Share Posted November 29, 2008 Update - I changed the front oxygen sensor but I got a P0174 while idling in traffic today. I checked the vacuum lines again and no leaks. I think I will check the injectors to see if they are seated good next. I have not installed the fuel pump yet due to the weather being bad and my garage being cluttered. Another thing I have noticed is that the engine will not run good after the car has been sitting on an incline with the front of the car up. If the front is down it is fine. Fuel pressure is still 30#'s and still hard starting. I am also leary of a vacuum leak though but I just can not find one. The codes are not constant just intermittent. I may try a new pcv valve to see if it is sticking. I had those codes on my '01 STS...turned out to be the rubber base gasket between the throttle body and the intake manifold,it was cracked @the bottom,where you cannot see it,until you pulled it off. I don't know if they used that on the '97,maybe someone could chime in. Link to comment Share on other sites More sharing options...
PAUL T Posted January 15, 2009 Author Report Share Posted January 15, 2009 Update - I changed the front oxygen sensor but I got a P0174 while idling in traffic today. I checked the vacuum lines again and no leaks. I think I will check the injectors to see if they are seated good next. I have not installed the fuel pump yet due to the weather being bad and my garage being cluttered. Another thing I have noticed is that the engine will not run good after the car has been sitting on an incline with the front of the car up. If the front is down it is fine. Fuel pressure is still 30#'s and still hard starting. I am also leary of a vacuum leak though but I just can not find one. The codes are not constant just intermittent. I may try a new pcv valve to see if it is sticking. Update - I still have not changed the fuel pump and I am leaning more toward a vacuum leak. If it was not for the hard cold starts I would not think there was a problem. I have not checked the fuel pressure lately but it never fell below 30lbs. all the times I checked it. Codes have not come up for a few weeks. I have search my 97 shop manual and can not find a good picture or schematic of the vacuum or EVAP system. If anyone knows where it is in the manual give me a page number or a schematic diagram. I have found a short hose with an open end coming out of the vacuum purge switch. It looks like it should be connected to something but I can not find a dangling hose. I might have to check for charcoal contamination of the EVAP system also. There is also a gasket (not a plenum) between the throttle body and the throttle body spacer, I will check there when the weather breaks. It is going to be around 0 degrees in the morning, it has to get a little warmer before I get back under the hood. I will keep this thread running until I find the answer for future reference. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 15, 2009 Report Share Posted January 15, 2009 The best pictures I can find of the EVAP solenoid is on pages 6-826. The repair diagrams on pages 6-770 show two hoses on the vacuum switch, and the diagram on page 6-826 shows one line going to the throttle body and the other going to the canister. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
PAUL T Posted January 15, 2009 Author Report Share Posted January 15, 2009 The best pictures I can find of the EVAP solenoid is on pages 6-826. The repair diagrams on pages 6-770 show two hoses on the vacuum switch, and the diagram on page 6-826 shows one line going to the throttle body and the other going to the canister. It looks like I am missing the hose that goes from the vacuum switch to the canister. I only have a 3" stub that runs in that direction. I guess I am going to have to crawl under the car and follow the hose from the canister back to the vacuum switch. I hope that is the fix because it would be an easy one and I can just save the fuel pump for another day. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 15, 2009 Report Share Posted January 15, 2009 The hose probably fell down the back of the engine. I would start by looking down between the engine and transmission and see if I could find a loose vacuum hose there. Then, look up from under the car between the transmission and engine back near the firewall. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
PAUL T Posted January 16, 2009 Author Report Share Posted January 16, 2009 O.K. Here is a picture of the EVAP Canister Purge Solenoid (lower left) and the EVAP Vacuum Switch off (upper right) out of my 97 Deville. I can not find a good picture in the manual, can anyone tell me what is connected into the Vacuum Switch hose shown coming out the side of the switch? I thought the hose to the EVAP canister went into it but it is connected to the Canister Purge Solenoid (lower left). Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 17, 2009 Report Share Posted January 17, 2009 It's the hose to your throttle body. With that hose off, that is your vacuum leak. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
PAUL T Posted January 17, 2009 Author Report Share Posted January 17, 2009 It's the hose to your throttle body. With that hose off, that is your vacuum leak. Where does it attach to the throttle body? I can not find anything missing. The hose beside the plug on the purge solenoid (lower left) goes to the throttle body. Any pictures? Link to comment Share on other sites More sharing options...
PAUL T Posted January 20, 2009 Author Report Share Posted January 20, 2009 Update, still no luck with the hard cold starts. I can not find any vacuum leaks. I have not checked the fuel pressure lately. Car runs fine other than hard cold starts. No codes now. I still have the fuel pump to put on but I am not sure that is the problem yet. I have been driving this thing for 3 months now this way. If it was a fuel pump I would think it would have let me down by now. I want to check the throttle body to make sure it is clean with no plugged up holes, but It will have to warm up a bit around here. I might spring for a new FPR before I put on the fuel pump. Any other suggestions? Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 20, 2009 Report Share Posted January 20, 2009 Have you checked the fuel pump relay? When you turn the key on, do you immediately hear the pump? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 20, 2009 Report Share Posted January 20, 2009 O.K. Here is a picture of the EVAP Canister Purge Solenoid (lower left) and the EVAP Vacuum Switch off (upper right) out of my 97 Deville. I can not find a good picture in the manual, can anyone tell me what is connected into the Vacuum Switch hose shown coming out the side of the switch? I thought the hose to the EVAP canister went into it but it is connected to the Canister Purge Solenoid (lower left). Does it look like there was a hose connected to it? Could that be a fresh air intake? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted January 21, 2009 Author Report Share Posted January 21, 2009 Have you checked the fuel pump relay? When you turn the key on, do you immediately hear the pump? I am hard of hearing but I think I hear it kick in. I just switched the relays around so I will see if it makes a difference in the morning. As far as the hose I really do not know. The 97 manual tells you how to unhook the switch and refers to disconnect/reconnect the hoses, that is it. No discription no diagrams, no explaination. I really notice that the 97 service manual lacks alot of information I had in my 94 manual. When I start the car in the mornings it will crank and almost start several times then all of a sudden it is like the computer kicks in and it just takes right off. I thought it was the open/closed loop thing. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 21, 2009 Report Share Posted January 21, 2009 The missing hose is the purge line feed to the manifold. The diagram shows it going to the throttle body. Someone who has a car apart or a photo needs to step up. I have no room to approach the car while it's in the garage and don't relish working in the driveway in this weather. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
PAUL T Posted January 21, 2009 Author Report Share Posted January 21, 2009 The missing hose is the purge line feed to the manifold. The diagram shows it going to the throttle body. Someone who has a car apart or a photo needs to step up. I have no room to approach the car while it's in the garage and don't relish working in the driveway in this weather. What diagram are you pertaining to, is it in the manual? There is a line from the throttle body going to the purge solenoid. Link to comment Share on other sites More sharing options...
winterset Posted January 22, 2009 Report Share Posted January 22, 2009 As BBF mentioned, check your Fuel pump relay. If the relay is bad, the car uses the oil pressure switch as a backup. it's not till the electric starter cranks a bit that the oil pressure builds up & engages the fuel pump - which eventually starts the car. - this sounds like your scenario. please let us know if/when you checked this out. Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 22, 2009 Report Share Posted January 22, 2009 As BBF mentioned, check your Fuel pump relay. If the relay is bad, the car uses the oil pressure switch as a backup. it's not till the electric starter cranks a bit that the oil pressure builds up & engages the fuel pump - which eventually starts the car. - this sounds like your scenario. please let us know if/when you checked this out. You read my mind. I didn't elaborate because I am not 100% sure what years have that back up system, I think they did away with this at some point, I know the earlier NSs had this. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted January 23, 2009 Author Report Share Posted January 23, 2009 As BBF mentioned, check your Fuel pump relay. If the relay is bad, the car uses the oil pressure switch as a backup. it's not till the electric starter cranks a bit that the oil pressure builds up & engages the fuel pump - which eventually starts the car. - this sounds like your scenario. please let us know if/when you checked this out. You read my mind. I didn't elaborate because I am not 100% sure what years have that back up system, I think they did away with this at some point, I know the earlier NSs had this. I switched the Fuel pump relay with the a/c compressor relay last night and the car started alot faster this morning, only one crank. I was pleasantly surprised. If this continues then I will have to save the fuel pump for another day. I had switched the relays earlier but I never noticed a difference because I did not leave them switched overnight, when the hard cold starts were the worst. I will have to measure the fuel pressure now to see if there is a difference. I will let you know tomorrow if the fuel pressure is back up. Thanks alot for all the help. You guys are great!!! Link to comment Share on other sites More sharing options...
PAUL T Posted January 23, 2009 Author Report Share Posted January 23, 2009 Just checked the fuel pressure this evening and it is only showing 36-38 pounds, but that is an improvement from 30 pounds before. I think I am going to buy a new relay and see if it does any better. Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 23, 2009 Report Share Posted January 23, 2009 Just checked the fuel pressure this evening and it is only showing 36-38 pounds, but that is an improvement from 30 pounds before. I think I am going to buy a new relay and see if it does any better. Sounds like you might have found something with the increase in fuel pressure, let us know how this turns out. I will look in my manual shortly (96 manual) and see if 96 had this fuel pump back up system. Even if the backup system was discontinued it is very possible that the relay contacts are pitted and burned causing resistance that would negatively impact the current going to the pump. Cold weather causes resistance all by itself maybe the cold weather put the relay over its ability to conduct current threshold Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted January 23, 2009 Author Report Share Posted January 23, 2009 I was also looking at the battery cables and they look like they could use a good cleaning or possibly replacing. I will let you all know what happens. I hope I also get back the 1-2 mpg's that I had before. Link to comment Share on other sites More sharing options...
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