Monaco500 Posted March 19, 2006 Report Share Posted March 19, 2006 Hello everyone, Just another update with my STS woes. THe car died on me again Monday, but this time would not restart. Got a new code: PO19. Fuel pump relay. This time, I had it towed to the dealer figuring they would be able to provide more meaningful diagnosis than the other shops I brought it to. First, they said their diagnostic equipment could not communicate with my PCM and that my fuel pressure bounced between 15 and 30 psi. My new (reman) PCM came in from Brasington GM (gmotors.com) and I installed it in the dealer's parking lot. Car wouldn't start. The shop brought in the car and was able to communicate with the PCM with their diagnostics equipment. They were able to get the car started, but it continually wanted to die: fuel pressure around 12-15 psi (should be around 50 psi?) They said I have been chasing two different problems: Fuel pump and the Ignition Control Module. The dealer has been great in that they have no problem with me ordering the parts elsewhere at cheaper prices while my car sits in their lot. Does this sound right? Would the ICM be causing my surging, stalling, etc problems without setting additional codes? Both the fuel pump and ICM are pricy items; I'll be around $1500 in repairs in the past few months after buying the pump and ICM. Thoughts? Thanks for your help!! Eric Link to comment Share on other sites More sharing options...
Ranger Posted March 20, 2006 Report Share Posted March 20, 2006 I don't know about the PCM, but it sure as hell ain't gonna run on 12-15 psi fuel pressure. Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 20, 2006 Report Share Posted March 20, 2006 Have you changed the fuel pump relay? Did you change the fuel 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...
Vince P Posted March 20, 2006 Report Share Posted March 20, 2006 Erick, The way I see it, is that your fuel pump regulator has gone bad. 1. If the fuel pump relay goes bad the car will start with a little of difficultly. What happens is as you crank the engine the oil pressure raises causing the fuel pressure switch (part of the oil presure switch) to operate. Normally, what happens it that the fuel pressure relay operates for 4 seconds, then turns off. This will give you enough pressure to start the car. Then it turns off. When the car is started the fuel pump is operated thruough the oil pressure switch not the PCM (which operates the fuel pressue relay). This is a safety system. 2. The fuel pressue on a 94 North star should be about 45psi. 3. The way to test it is to connect a fuel pressue gauge at the stroder valve, next to the valve body. Turn on the key. You can hear the pump work for 2 to 4 seconds then turn off. It should hold that pressue. You can listen to the pump go on then of in between 2 and 4 seconds. If the prssure drops then there is a leak, most likely the fuel pressure regulator. 4. When the cars starts it should maintain 40 to 45 psi. That is the way I see it. Vince P Link to comment Share on other sites More sharing options...
Monaco500 Posted March 20, 2006 Author Report Share Posted March 20, 2006 Hello Vince, Thanks for your input. After reading other posts, I suspected that I may be having FPR problems. In fact, I bought one when I bought my reman PCM. I talked to the shop at the dealership, and they said that they installed a fuel pressure gage as the line comes up near the throttle body (sounds like where you suggested). They said that because the pressure was low there that it was likely the pump. Before I took the car to the dealer, I checked the FPR for leakage out of the top by pulling the top of the intake, turning the key switch to on, and looking for leaks. I didn't see any. Could my FPR be bad without leaking at the top of the regulator? If the regulator were bad, would the resultant pressure at the gage be around 15 psi? If that were the case, would the excess fuel just be draining into the intake? Sounds like that could explain a decrease in gas mileage... Thanks for your thoughts, Eric Erick, The way I see it, is that your fuel pump regulator has gone bad. 1. If the fuel pump relay goes bad the car will start with a little of difficultly. What happens is as you crank the engine the oil pressure raises causing the fuel pressure switch (part of the oil presure switch) to operate. Normally, what happens it that the fuel pressure relay operates for 4 seconds, then turns off. This will give you enough pressure to start the car. Then it turns off. When the car is started the fuel pump is operated thruough the oil pressure switch not the PCM (which operates the fuel pressue relay). This is a safety system. 2. The fuel pressue on a 94 North star should be about 45psi. 3. The way to test it is to connect a fuel pressue gauge at the stroder valve, next to the valve body. Turn on the key. You can hear the pump work for 2 to 4 seconds then turn off. It should hold that pressue. You can listen to the pump go on then of in between 2 and 4 seconds. If the prssure drops then there is a leak, most likely the fuel pressure regulator. 4. When the cars starts it should maintain 40 to 45 psi. That is the way I see it. Vince P Link to comment Share on other sites More sharing options...
jfreezn Posted March 20, 2006 Report Share Posted March 20, 2006 My 94 Bravada, which uses a similar fuel pump circuit, was also dieing on occasion, and became more frequent. Monitoring the fuel pressure by taping a gauge to the windshield ( don't ever bring a fuel line inside the car) showed an intermitent pump. I pulled the pump out of the tank, and found the power wire to the pump was burned off and the ends were just bumping together! Arcing in a gasoline tank! Good thing the concentration of fumes was so high that it couldn't ignite! I highly reccomend that if you replace the pump, get the correct Delco replacement, don't try to cheap out at Autozone or such. The pump must make a minimum pressure for many years and some replacements are so marginal that they last just long enough to get out of warranty. Try GMpartsdirect.com or similar. There was a seller on EBAY that had 12 of them at a good price (about a year ago), maybe his "supplier" has restocked him. By the way, Harbor Freights current ad carries a fuel pressure tester, with various adapters, and the gauge for about $20. I made mine from a freon hose and a 60 psi liquid filled gauge from Graingers, but they typically cost about $40 at Checker, etc Good luck, Jim in Phoenix Jim in Phoenix Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 20, 2006 Report Share Posted March 20, 2006 Eric, a month ago Paul T said to check your FPR, if you have one just replace it and eliminate that possiblity, here is Pauls post on 2/16/2006: P080 is a code for FUEL SYSTEM RICH, immediately check your FPR (Fuel Pressure Regulator). 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...
Ranger Posted March 20, 2006 Report Share Posted March 20, 2006 Monaco, Yes the FPR can be bad without leaking at the nipple. That is not common but can happen. I am aware of one guy on the other caddy site that had a starting problem and the FPR checked out ok. I suggested that he put a hand held vacuum pump on the FPR and pump down a vacuum and watch the guage. Sure enough, it would not hold a vacuum. He changed it and that solved his problem. If it is leaking, yes, the fuel goes into the manifold and is burnt as unmetered fuel, resulting in a decrease in fuel milage. I am not sure if a bad FPR would cause fuel line pressure to drop as low as 15 psi but I suppose it may be possible. Link to comment Share on other sites More sharing options...
Vince P Posted March 21, 2006 Report Share Posted March 21, 2006 Erik, Sometimes it is difficult to determine if the diaphram in the Fuel Pressure Regulator is leaking. I struggled with this for about 6 months. After I took the top of the intake manifold off three time and with a lot of suction, I was able to draw a little fuel. The fuel on the bottom of the intake manifold is drawn into the engine. I had very little puddling. When I replaced my Fuel Pressure Regulator, I wrote a detailed primer on the whole proceedure with a lot of cautions and some variations for the Factory Service Manual. It is an easy process once you understand what is going on. Search for my primer on this site. If you cannot find it and want it, let me know and I will get it you. I am sure I have it stored on my other computer. All my problems went away after I replaced my Fuel Pressure Regualator. Good Luck Vince P Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 22, 2006 Report Share Posted March 22, 2006 Erik, in your original post you stated that you replaced your MAP. Were you getting an MAP code and is that why you replaced it? Here is your original post: http://caddyinfo.ipbhost.com/index.php?showtopic=8547&hl= In your most recent posts you discussed fuel pump and possibly replacing it. Have you hooked up a fuel pressure guage? http://caddyinfo.ipbhost.com/index.php?showtopic=8741&hl= I still think you need to replace your FPR as others have said, BUT: The reason I am back is something that I read in another post by winterset, read winterset's statement regarding a connection between the MAP and Fuel Pump in this thread, Mike http://caddyinfo.ipbhost.com/index.php?showtopic=8879 You can buy a fuel pressure tester at any parts store or SEARS 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...
Monaco500 Posted April 5, 2006 Author Report Share Posted April 5, 2006 Mike, Thanks for the link from Winterset. I just had the dealership run diagnostics and replace my fuel pump. They were kind enough to allow me to replace the PCM and ICM in the parking lot to avoid excessive labor charges. I got the car yesterday. THere is a check engine light on; they said it was from the idle learn procedure not being performed. I drove it to work, and did the idle learn procedure in the parking lot. While going through the procedure, when I started the car after going in/out of diagnostics mode with the key in the on position, the car surged with irratic rpm and stalled again. Frustrating! It tripped PO32, PO34, and PO71 codes, all related to the MAP sensor (which I replaced about three months ago). Because I now have a new fuel pump, I am suspecting that my MAP problem is not fuel pump related. I asked the dealer about the FPR thinking that if it was bad, it would certainly leak fuel into the manifold under higher pressure of a new fuel pump. THey said that they checked the FPR and that it was fine. Any thoughts? Could the MAP codes be "ghost codes" from another problem? What could have caused the irradic idle/stalling? Thanks for your help! Eric Erik, in your original post you stated that you replaced your MAP. Were you getting an MAP code and is that why you replaced it? Here is your original post: http://caddyinfo.ipbhost.com/index.php?showtopic=8547&hl= In your most recent posts you discussed fuel pump and possibly replacing it. Have you hooked up a fuel pressure guage? http://caddyinfo.ipbhost.com/index.php?showtopic=8741&hl= I still think you need to replace your FPR as others have said, BUT: The reason I am back is something that I read in another post by winterset, read winterset's statement regarding a connection between the MAP and Fuel Pump in this thread, Mike http://caddyinfo.ipbhost.com/index.php?showtopic=8879 You can buy a fuel pressure tester at any parts store or SEARS Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 5, 2006 Report Share Posted April 5, 2006 Was your MAP an OEM MAP? Consider that it is possible that the new MAP was malfunctioning. Check the plug connection to make sure the contacts are not corroded, worn or loose. It sounded like you had the problem licked and it came back, it is sounding intermittant to me. 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...
KHE Posted April 5, 2006 Report Share Posted April 5, 2006 Idle learn procedure just resets the compensation for a dirty throttle body. Not doing it would not cause the service engine soon light to be on. Hold the dealer's feet to the fire on this one. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Monaco500 Posted April 6, 2006 Author Report Share Posted April 6, 2006 Hey guys, The Idle speed control module was out of adjustment. I went through the adjustment procedure, and the PO80 code (and check engine light) went away. I haven't driven it much since then (because I'm afraid to get stranded again), but it didn't trip any map codes. Is it possible that when the PCM didn't know what was going on with the Idle speed control module that an adverse operating condition ensued resulting in MAP error codes? Seems unlikely to me, but... The MAP was not a GM part... Thanks for your help, Eric Link to comment Share on other sites More sharing options...
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