: Stranded out of town



fristim
03-26-07, 06:25 PM
Hey there fellow cady lovers. I own a 98 concours 191000 on here. Currently out of town and went to accelerate into traffic and lost power. Pull the codes and I get P0231 - Fuel Pump Feedback Circuit Low Voltage. Switched the ac relay with the fuel pump relay same thing. Put a fuel pressure gauge on it and nothing. pull the fuse for the fuel pum and put a voltometer on it and I get no voltage. Now Im assuming that there must be a circuit break probably in the fuel pump itself which is why Im not getting any voltage at the fuse for the fuel pump. Anyone ever done a fuel pump change? If so what do I need to do? Thankfully there is about a 4 gallons of gas in the tank. Thanks for your help.

Edahall
03-26-07, 08:00 PM
I had the same thing happen to me on my 88 Eldorado when I was out of town like you but it happened right after I filled with gas and it was a nightmare getting the thing down full of gas.

The newer Devilles had an access hole in the trunk. I think yours doesn't but you might want to double check.

Basically you need to lower the gas tank and there are 2 straps that are holding it up. Those straps need to be removed and the hoses that are attached to the tank need to removed and it should drop right down.

Good luck... To have this job done would cost close to $500.

fristim
03-26-07, 09:41 PM
ok well i dropped the tank and did a continouity test on the pump, and I got have a complete circuit. Ran 12 volts and the pump ran, plugged it back into the harness and nothing, checked the harness and no voltage to the pump when I turn on the key, any suggestions?

Ranger
03-26-07, 09:44 PM
Fuel pump relay.

fristim
03-26-07, 10:20 PM
fuel pump relay was the first thing I tried, switched the ac relay with the fuel pump and got nothing.

Ranger
03-26-07, 11:28 PM
Ah, so you did. Read it too fast I guess, sorry.

fristim
03-26-07, 11:35 PM
Now is the ac relay and the fuel pump relay interchangable.

Ranger
03-26-07, 11:42 PM
Not sure, but I would think so.

deville555
03-26-07, 11:55 PM
Yes they are interchangeable.

Edahall
03-27-07, 01:39 PM
If you're planning on keeping the car, you might just want to put in a new fuel pump while the tank is down. Mine went 220k miles before it failed.

fubar569
03-27-07, 02:11 PM
screw pissing with the original harness. youve isolated the issue. do what i did in my old car to get more consistent pump performance....run your own wiring.

1 relay
heavy gauge wire from battery to relay (fused)
ignition controlled power source
more heavy wire to FP +
and ground wires

this makes sure your pump always has the highest voltage possible. if your battery sees 13.5 thats what the pump gets...not 11.1 because of the dinky factory wiring...

you'll be better off at the end of the day...assuming your car wont throw a fit about not seeing any power on the stock FP circuit

fristim
03-27-07, 05:25 PM
Well after I put 12 volts to the pump and it ran I plugged it back in and still nothing. So I checked the relay plug in on the fuse box for voltage and I get 12.2 volts for about 2 secs when I turn the key on. Checked the other side of the relay circuit and I get nothing. So I went ahead and pulled 12 volts from another fuse, ran a jumper wire to the fuel pump fuse and there we go, got the fuel pump running and the car fired right up. But now I a whole shit load of codes that follow. Any Ideas thanks.

P0102 - Mass Air Flow (MAF) Sensor Circuit Low Frequency
P0753 - 1-2 Shift Solenoid Circuit Electrical
P0758 - 2-3 Shift Solenoid Circuit Electrical
P1645 - Evaporative Emission (EVAP) Vent Solenoid Contorl Circuit
P1860 - TCC PWM Solenoid Circuit Electrical
Those are all current by the way.

fubar569
03-27-07, 08:54 PM
Well after I put 12 volts to the pump and it ran I plugged it back in and still nothing. So I checked the relay plug in on the fuse box for voltage and I get 12.2 volts for about 2 secs when I turn the key on. Checked the other side of the relay circuit and I get nothing. So I went ahead and pulled 12 volts from another fuse, ran a jumper wire to the fuel pump fuse and there we go, got the fuel pump running and the car fired right up. But now I a whole shit load of codes that follow. Any Ideas thanks.

P0102 - Mass Air Flow (MAF) Sensor Circuit Low Frequency
P0753 - 1-2 Shift Solenoid Circuit Electrical
P0758 - 2-3 Shift Solenoid Circuit Electrical
P1645 - Evaporative Emission (EVAP) Vent Solenoid Contorl Circuit
P1860 - TCC PWM Solenoid Circuit Electrical
Those are all current by the way.


3 of the 5 are transmission related...where did you pull that 12v from? maybe a reference circuit by accident?

what happens if you 12v from the battery (or another place) instead of your source. do the codes disappear?

fristim
03-27-07, 10:15 PM
pulled the 12 volts both from the battery and from various other sources still get the same codes though.

fubar569
03-28-07, 01:54 AM
if you clear them andtake a drive do they come back? how does the car seem to run? it seems really odd it would spring all those other codes after fixing your fueling issue

fristim
03-28-07, 01:14 PM
If I clear the codes and dont run a jumper wire to fuel pump relay the only code i get is 231 low voltage to fuel pump relay, but of course the car doesnt run. But no other codes, I would assume the other codes only show when the car is running. So when I jump 12 volts to the fuel pump fuse I no longer get the 231 but I get all the other codes along with the SES light. Ya see it just died when I was accelerating very hard which might lead me to believe that maybe with torque pull of the motor that something might have come loss that feeds power to these components. It runs ok but I can tell that its not getting the right reading from the mass air flow sensor, hense the wierd idle and loping that the motor does, and i havent driven it as Im scared to damage something. I would also assume that the damn thing prolly wouldnt shift also. Seems like I've lost a postive "trunk" feed that might actually power all of these components. A wiring diagram would be great you happen to know where i might get one?

fubar569
03-28-07, 03:40 PM
whenever i need totake a peek my friends at the dealership pull thiers out of storage for me. maybe someone here has an actual FSM they can help you pinpoint this issue with...cause from here on out im lost

good luck!

scl98sts
01-25-08, 04:23 PM
did you get this fixed. i have tried to pm some of the people who respond to these problems but this message board says i need 20 post to pm anybody so please nobody get mad.

zonie77
01-26-08, 08:36 PM
I have seen 2 elec pumps that run on 12v off a charger but not off the car wiring (even when I ran a heavier wire to the connector). New pump worked fine. The new pump was MUCH quieter and smoother too. I think a new pump will fix it.

scl98sts
02-04-08, 06:13 PM
i have all of the codes that you have but dont have a problem with the fuel pump . p0753,p0758,p0102,p1645,p1860. the car was running fine then the power steering pressure hose busted and the fluid got everywhere , could it be that the fluid is causing there to be a short ? i cant get anybody on this whole forum to help me , i have put the car up for sale at a really cheap price because nobody seems to know why these codes come up and/ or how to fix them, i dont want to mess it up more and have to junk the car. i have cleared the codes and they keep coming back. if anyone can help thanks. i love my cadillacs my first was a 96 eldorado,97sts,99escalade,77coupe,88fleetwood,and now a 98 sts

AJxtcman
02-04-08, 08:05 PM
i have all of the codes that you have but dont have a problem with the fuel pump . p0753,p0758,p0102,p1645,p1860. the car was running fine then the power steering pressure hose busted and the fluid got everywhere , could it be that the fluid is causing there to be a short ? i cant get anybody on this whole forum to help me , i have put the car up for sale at a really cheap price because nobody seems to know why these codes come up and/ or how to fix them, i dont want to mess it up more and have to junk the car. i have cleared the codes and they keep coming back. if anyone can help thanks. i love my cadillacs my first was a 96 eldorado,97sts,99escalade,77coupe,88fleetwood,and now a 98 sts

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/102992-wiring-scheme-98-deville.html