Jeff Posted July 27, 2006 Report Share Posted July 27, 2006 Suppose you too were a idiot and you dropped $324.00 on a fuel pump and busted your hump half the day putting that sucker in all by yourself in the rain, then turned the key on and nothing happened, even though you checked all the fuses and relays you knew of, and suppose you mangaed to muster enough restraint to keep from bustin out every window in the heap and collected your thoughts enough to live to fight another day, what would be your next step? You know, just supposing that happened... Jeff Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 Don't be so hard on yourself. Did you disconnect the battery when you did the job, some safety conscious mechanics do that.. First check the battery to see if somehow it was discharged, then I would clean the battery connections. Maybe having the hood open in the rain, was just enough to get moisture into the battery connections along with corrosion that you are no longer getting a good connection there. Pay close attention to the positive cables pull the insulator off and clean inside... Mike 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...
JimD Posted July 27, 2006 Report Share Posted July 27, 2006 For sure, I would not buy a lottery ticket. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 For sure, I would not buy a lottery ticket. That's grand... I guess I could've done that instead. After all, it was Wednesday night! HECK- I could've bought 324 tickets and maybe won a few dollars. I wrote water pump, but I meant FUEL pump. I edited my original post. I did have the hood open the whole time though... Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted July 27, 2006 Report Share Posted July 27, 2006 I would reconnect the negative battery cable. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
zonie77 Posted July 27, 2006 Report Share Posted July 27, 2006 The wiring harness in the tank can go bad. Did you inspect it very carefully? Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 All the wires and connectors that I saw looked like new. There's a 20A fuse and a relay under the hood on the driver's side over the front wheel. Is that all there is? Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 Suppose you too were a idiot and you dropped $324.00 on a fuel pump and busted your hump half the day putting that sucker in all by yourself in the rain, then turned the key on and nothing happened, even though you checked all the fuses and relays you knew of, and suppose you mangaed to muster enough restraint to keep from bustin out every window in the heap and collected your thoughts enough to live to fight another day, what would be your next step? You know, just supposing that happened... Jeff I assume when you say NOTHING you mean that the starter does not turn over or do you mean, the engine turns over but does NOT start? Please clarify 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...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 I'm sorry... When I turn the key on the pump does nothing. You know how it runs for a second or so when you first turn it on? I thought maybe it's so quiet, I just didn't hear it. I put a pressure gauge on the rail and nothing. Everything else powers up- bells, whistles, radio, lights... no fuel pump pressure. That's exactly what the old pump did. I could turn the starter over, but it just wouldn't start up because of no fuel. I haven't spun it over with the new pump, but I know it will. Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 If you have a volt meter, I would check the power to the relay, someone else here is having a problem with possible corrosion in the relay center. Make sure there is no corrosion where the relay is plugged in and that the relay is good. Then check for power at the pump when the key is turned on. If you did this what were your findings. 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 July 27, 2006 Report Share Posted July 27, 2006 If the relay fails, the engine will start after enough oil pressure is built up. If that happens, then the relay is bad. Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 But if there is no fuel at the rail, how will it crank? Won't a bad relay keep it from getting any fuel at all? Shouldn't I be hearing it "buzz" for a second when I turn the key on? Link to comment Share on other sites More sharing options...
Ranger Posted July 27, 2006 Report Share Posted July 27, 2006 Assuming it is the relay, when enough oil pressure is built up, the relay is overridden and the pump is energized so it will run and pressurize the system, hense the long crank times. I am assuming you have power to the starter so it will crank. Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 I remember now... back when this first started, I got a message on the dash that said "SERVICE FUEL SYSTEM". I did not get any codes relating to that though. Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 Assuming it is the relay, when enough oil pressure is built up, the relay is overridden and the pump is energized so it will run and pressurize the system, hense the long crank times. I am assuming you have power to the starter so it will crank. I always forget this, it needs 5 to 6 pounds of pressure to engage the oil pressure fuel pump backup switch. Have you checked for continuity, maybe a broken or chafted wire or bad or disconnected ground. 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 July 27, 2006 Report Share Posted July 27, 2006 Hmm, wish I still had my '97 FSM. Not sure if that message means relay or pump. Anyway, I'd check out that relay before going any further. Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 Yes- I can spin it over, just no cranky. SO even though it's not pressuring up when I turn the key on, it may kick on when the oil pressure gets up?? Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 Yes- I can spin it over, just no cranky. SO even though it's not pressuring up when I turn the key on, it may kick on when the oil pressure gets up?? Yes, when the oil pressure hits about 5 or 6 pounds, the backup fuel pump activate switch will engage and start your fuel pump, as ranger stated it takes a long crank... That would indicate that your primary relay circuit is messed up some how. On the other hand, if it still does not start, I would begin checking continuity between the fuel pump POWER wiring to 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...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 So basically, I just threw 324 bucks right down the crapper? Link to comment Share on other sites More sharing options...
joeb Posted July 27, 2006 Report Share Posted July 27, 2006 well, you do have a new FP. I replaced mine and it turns out it was corrosion on the wire harness inside the tank. but the new FP assy includes the suspect wire harness so its all good now. after 10yrs putting in a new FP is not a bad idea. would you prefer to take your chances and be stranded out in the middle of nowhere? did you check your old FP? are you saying its good? Link to comment Share on other sites More sharing options...
JimD Posted July 27, 2006 Report Share Posted July 27, 2006 If the difference between '97 and '98 includes a major change in the fuel pump circuit, you can disregard this post. But I think the pump control is the same year to year. The oil pressure switch does not trigger an alternative source of voltage for the fuel pump that by-passes the fuel pump relay and fuel pump fuse. The oil pressure switch only triggers an alternative ground for the fuel pump relay. The fuel pump fuse and the fuel pump relay plus all associated wiring are still in play even if cranking the engine to provide some minimum amount of oil pressure causes the pump to run. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Jeff Posted July 27, 2006 Author Report Share Posted July 27, 2006 Good point, joeb. I'm going check the relay when I get home. Is the AC relay the same as the FP relay? Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2006 Report Share Posted July 27, 2006 Good Info Jim! I was too lazy to look in the manual, I need to do that however. I mentioned before that I am getting wildly erratic fuel gage readings, you know one minute I have 8 gallons the next 3 gallons... its nerveracking... I know there is a fuel level sensor that is part of the fuel pump assembly that I THINK is replacable but after 11 years, I think I should replace my entire fuel pump assembly especially since its LOUD at times... 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 July 28, 2006 Report Share Posted July 28, 2006 I stand corrected. Thanks Jim. Link to comment Share on other sites More sharing options...
WarrenJ Posted July 28, 2006 Report Share Posted July 28, 2006 If the difference between '97 and '98 includes a major change in the fuel pump circuit, you can disregard this post. But I think the pump control is the same year to year. The oil pressure switch does not trigger an alternative source of voltage for the fuel pump that by-passes the fuel pump relay and fuel pump fuse. The oil pressure switch only triggers an alternative ground for the fuel pump relay. The fuel pump fuse and the fuel pump relay plus all associated wiring are still in play even if cranking the engine to provide some minimum amount of oil pressure causes the pump to run. In the 1995 model, at least, the oil pressure switch is in the battery path, not the ground path. Also (at least in '95) a bad fuel pump relay will set a DTC. Wiring: http://s7.photobucket.com/albums/y299/WBuc...mgAnch=imgAnch1 Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
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