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Chrysler Fuel pump and battery Questions.
Maybe someone here knows the answers to a couple questions a friend of
mine has regarding Chrysler Fuel pumps and his battery. He has what he thinks is a dead fuel pump in his 94 Voyager. So he got a used pump and tested it with 12 volts to see it spin up. He then installed it and it still won't spin up in the tank. He 'thinks' he heard it spin when he put the key to 'run' once but no start. I am disabled and can't get under there to check it for him. I made a couple observations. One, the 'new' pump has 4 wires off the plug and the old one had 3. The ground for the gauge and the motor ground appear to be common in the old pump and separate in the new one so he soldered the two wires together. The 'old' pump will also spin up when hooked to a battery. The fuel pump relay looks good with nice clean contacts inside and on the spades and it clicks when the key is turned. Voltage was observed at the pump plug. Not enough maybe? His battery is acting wrong I 'think'. It has a good 24 hours on the charger to bring it up over 14 volts. 30 seconds with the lights on to take the surface charge off, then off drops it to 13V. When the key hits run, it dives to 12.1 or so volts. When the starter turns, it drops to 10.2V. I am of the opinion the battery doesn't have enough power to fire it up maybe. Could he just plain have the wrong pump in there? Any suggestions or guesses would be appreciated. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's |
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On Fri, 21 Jan 2005 10:35:45 -0500, Mike Romain >
wrote: >Maybe someone here knows the answers to a couple questions a friend of >mine has regarding Chrysler Fuel pumps and his battery. > >He has what he thinks is a dead fuel pump in his 94 Voyager. > >So he got a used pump and tested it with 12 volts to see it spin up. He >then installed it and it still won't spin up in the tank. He 'thinks' >he heard it spin when he put the key to 'run' once but no start. I am >disabled and can't get under there to check it for him. > >I made a couple observations. One, the 'new' pump has 4 wires off the >plug and the old one had 3. The ground for the gauge and the motor >ground appear to be common in the old pump and separate in the new one >so he soldered the two wires together. > >The 'old' pump will also spin up when hooked to a battery. > >The fuel pump relay looks good with nice clean contacts inside and on >the spades and it clicks when the key is turned. Voltage was observed >at the pump plug. Not enough maybe? ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// >His battery is acting wrong I 'think'. It has a good 24 hours on the >charger to bring it up over 14 volts. A fully charged battery is 12.9 volts. > 30 seconds with the lights on to >take the surface charge off, then off drops it to 13V. When the key >hits run, it dives to 12.1 or so volts. When the starter turns, it >drops to 10.2V. Anything under 10.4 volts is considered *weak* but 10.4 volts or better is normal when you put a starter load on the battery. When you take the load off, it will return immediately to 12 point something. >I am of the opinion the battery doesn't have enough power to fire it up >maybe. See above. >Could he just plain have the wrong pump in there? > >Any suggestions or guesses would be appreciated. Check the fuel pressure regulator. Lg >Mike >86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 >88 Cherokee 235 BFG AT's |
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It should start with 10 volts. He needs to check for fuel pressure on the fuel rails on the intake manifold. Also check for spark while cranking. Mike Romain wrote: > > Maybe someone here knows the answers to a couple questions a friend of > mine has regarding Chrysler Fuel pumps and his battery. > > He has what he thinks is a dead fuel pump in his 94 Voyager. > > So he got a used pump and tested it with 12 volts to see it spin up. He > then installed it and it still won't spin up in the tank. He 'thinks' > he heard it spin when he put the key to 'run' once but no start. I am > disabled and can't get under there to check it for him. > > I made a couple observations. One, the 'new' pump has 4 wires off the > plug and the old one had 3. The ground for the gauge and the motor > ground appear to be common in the old pump and separate in the new one > so he soldered the two wires together. > > The 'old' pump will also spin up when hooked to a battery. > > The fuel pump relay looks good with nice clean contacts inside and on > the spades and it clicks when the key is turned. Voltage was observed > at the pump plug. Not enough maybe? > > His battery is acting wrong I 'think'. It has a good 24 hours on the > charger to bring it up over 14 volts. 30 seconds with the lights on to > take the surface charge off, then off drops it to 13V. When the key > hits run, it dives to 12.1 or so volts. When the starter turns, it > drops to 10.2V. > > I am of the opinion the battery doesn't have enough power to fire it up > maybe. > > Could he just plain have the wrong pump in there? > > Any suggestions or guesses would be appreciated. > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's -- Mike Walsh West Palm Beach, Florida, U.S.A. |
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I believe there is a dark green wire with black tracer at the pump
relay. That's the main power wire for the pump. It should be hot when cranking. Is it? You may have an initial prime for a few seconds, with the key in the on position, engine not cranking. After that, the computor will kill it, unless there is an rpm signal, you can't get a rpm signal without cranking the engine. If it is hot at the relay, check it at the pump plug, if that's ok, check the ground. If it will spin with B+ and a ground outside the vehicle, it should do the same thing on the vehicle. hmm |
#5
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Lawrence Glickman wrote: > > A fully charged battery is 12.9 volts. Nominal battery voltage is 12.6 volts, i.e. neither charging nor discharging. > Anything under 10.4 volts is considered *weak* > but 10.4 volts or better is normal when you put a starter load on the > battery. When you take the load off, it will return immediately to 12 > point something. 10 volts might be weak, but I have seen many engines start with 8 volts. -- Mike Walsh West Palm Beach, Florida, U.S.A. |
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He checked at the pump on those wires and had the same 10+ volts.
Do you think this is enough to spin it up? I am thinking a lack of amps as well with a weak battery cell. The charger does boil one cell harder than the rest and that one was low on water. I tried boosting and it sucked my new alternator and new battery hard enough to drop me from 2000 rpm on a hand throttle down to 800 rpm. Serious draw. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's oilyspill wrote: > > I believe there is a dark green wire with black tracer at the pump > relay. That's the main power wire for the pump. It should be hot when > cranking. Is it? You may have an initial prime for a few seconds, with > the key in the on position, engine not cranking. After that, the > computor will kill it, unless there is an rpm signal, you can't get a > rpm signal without cranking the engine. If it is hot at the relay, > check it at the pump plug, if that's ok, check the ground. If it will > spin with B+ and a ground outside the vehicle, it should do the same > thing on the vehicle. hmm |
#7
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I am wondering about the 10 volts and the available amps.
I tried a boost even and it sucked my new alternator and battery hard. Dropped me from 2000 rpm on a hand throttle down to 800 or so. Mike Mike Walsh wrote: > > It should start with 10 volts. He needs to check for fuel pressure on the fuel rails on the intake manifold. Also check for spark while cranking. > > Mike Romain wrote: > > > > Maybe someone here knows the answers to a couple questions a friend of > > mine has regarding Chrysler Fuel pumps and his battery. > > > > He has what he thinks is a dead fuel pump in his 94 Voyager. > > > > So he got a used pump and tested it with 12 volts to see it spin up. He > > then installed it and it still won't spin up in the tank. He 'thinks' > > he heard it spin when he put the key to 'run' once but no start. I am > > disabled and can't get under there to check it for him. > > > > I made a couple observations. One, the 'new' pump has 4 wires off the > > plug and the old one had 3. The ground for the gauge and the motor > > ground appear to be common in the old pump and separate in the new one > > so he soldered the two wires together. > > > > The 'old' pump will also spin up when hooked to a battery. > > > > The fuel pump relay looks good with nice clean contacts inside and on > > the spades and it clicks when the key is turned. Voltage was observed > > at the pump plug. Not enough maybe? > > > > His battery is acting wrong I 'think'. It has a good 24 hours on the > > charger to bring it up over 14 volts. 30 seconds with the lights on to > > take the surface charge off, then off drops it to 13V. When the key > > hits run, it dives to 12.1 or so volts. When the starter turns, it > > drops to 10.2V. > > > > I am of the opinion the battery doesn't have enough power to fire it up > > maybe. > > > > Could he just plain have the wrong pump in there? > > > > Any suggestions or guesses would be appreciated. > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 88 Cherokee 235 BFG AT's > > -- > Mike Walsh > West Palm Beach, Florida, U.S.A. |
#8
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What the heck have you got for an alternator that will drop your engine 1200
rpm? Man that must suck a LOT of power from the engine, or your engine doesn't produce much torque at 1200 rpm. I would guess a normal alternator would take at most 3 hp to turn, especially at such a low rpm. tad "Mike Romain" > wrote in message ... > He checked at the pump on those wires and had the same 10+ volts. > > Do you think this is enough to spin it up? > > I am thinking a lack of amps as well with a weak battery cell. The > charger does boil one cell harder than the rest and that one was low on > water. I tried boosting and it sucked my new alternator and new battery > hard enough to drop me from 2000 rpm on a hand throttle down to 800 > rpm. Serious draw. > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's > > oilyspill wrote: >> >> I believe there is a dark green wire with black tracer at the pump >> relay. That's the main power wire for the pump. It should be hot when >> cranking. Is it? You may have an initial prime for a few seconds, with >> the key in the on position, engine not cranking. After that, the >> computor will kill it, unless there is an rpm signal, you can't get a >> rpm signal without cranking the engine. If it is hot at the relay, >> check it at the pump plug, if that's ok, check the ground. If it will >> spin with B+ and a ground outside the vehicle, it should do the same >> thing on the vehicle. hmm |
#9
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That surprised the crap out of me too. My Jeep engine has 100% of it's
torque at around 1750 rpm and is a real strong runner climbing sand pit walls down to 400 rpm. It won't stall. The alternator is just a new remanufactured GM 'one wire' (3 wires actually) 70 amp unit I think with an Optima battery. My Warn HS9000i winch on full load doesn't drop my rpm like that unless I stall it and and that stall is a rated 450 amp draw. The only time I have seen that in the past was trying to boost a battery and start a vehicle with a dead cell if I remember right.... Even with no draw, when I hooked up the booster cables the rpm took about a 100 hit. I do have heavy gauge booster cables with good clamps Mike ottertailfamily wrote: > > What the heck have you got for an alternator that will drop your engine 1200 > rpm? Man that must suck a LOT of power from the engine, or your engine > doesn't produce much torque at 1200 rpm. I would guess a normal alternator > would take at most 3 hp to turn, especially at such a low rpm. > tad > > "Mike Romain" > wrote in message > ... > > He checked at the pump on those wires and had the same 10+ volts. > > > > Do you think this is enough to spin it up? > > > > I am thinking a lack of amps as well with a weak battery cell. The > > charger does boil one cell harder than the rest and that one was low on > > water. I tried boosting and it sucked my new alternator and new battery > > hard enough to drop me from 2000 rpm on a hand throttle down to 800 > > rpm. Serious draw. > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 88 Cherokee 235 BFG AT's > > > > oilyspill wrote: > >> > >> I believe there is a dark green wire with black tracer at the pump > >> relay. That's the main power wire for the pump. It should be hot when > >> cranking. Is it? You may have an initial prime for a few seconds, with > >> the key in the on position, engine not cranking. After that, the > >> computor will kill it, unless there is an rpm signal, you can't get a > >> rpm signal without cranking the engine. If it is hot at the relay, > >> check it at the pump plug, if that's ok, check the ground. If it will > >> spin with B+ and a ground outside the vehicle, it should do the same > >> thing on the vehicle. hmm |
#10
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On Fri, 21 Jan 2005 20:10:07 GMT, Mike Walsh >
wrote: > > >Lawrence Glickman wrote: >> >> A fully charged battery is 12.9 volts. > >Nominal battery voltage is 12.6 volts, i.e. neither charging nor discharging. Where do you get this *stuff* from? My fully charged battery -measured out at 12.9 VDC Now, a week later, and with no charging or load given to it, it reads 12.82 VDC. Stay away from those books and pay more attention to what your eyes are telling you. Lg >> Anything under 10.4 volts is considered *weak* >> but 10.4 volts or better is normal when you put a starter load on the >> battery. When you take the load off, it will return immediately to 12 >> point something. > >10 volts might be weak, but I have seen many engines start with 8 volts. |
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