4.7L Hard Starting
From : s miller
Q: hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. it doesnt seem to make any difference whether the engine is cold or warm and there are no other drivability problems the idle is fine etc. no trouble codes are being set. due to the time element nature of the problem i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i have also read of similar problems being caused by the throttle position sensor or the crank position sensor but the fact that the engine will re-start immediately and that there are no other drivability issues and no trouble codes would seem to lead one away from these causes. any thoughts or pointers would be appreciated... - seth .
Replies:
From : twix
i agree. i had the same same problem same solution. the fuel pump originally shipped with these trucks had some know issues. i had to replace mine twice. dc redesigned the fuel pump because of the number of problems being fixed under warranty but there is no recall or tsb for this. on thu 23 oct 2003 134821 gmt paul johnson thejohnsons@frontiernet.net wrote hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. ... ...i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i had this problem with my 95 v-10. it turned out to be a defective fuel pump- was allowing fuel to bleed back. new fuel pump under warranty fortunately completely solved the problem. paul johnson .
From : ron s
i have a 94 dakota with the 3.9 and it sort of does the same thing. just turning the key to the on position and waiting a few seconds while i put my seatbelt on lets the fuel pump build up pressure and it will start in an instant hot or cold. if i dont give it that little bit of time it still starts okay but the cranking time is longer. ron .
From : nitpik
the o2 sensor is out of the loop when doing a cold start. perhaps restricted exhstcat convtr o2 sensor air control valve. each react to temp. changeseither directly or indirectly the codes often will not show up til a sensor is completely bad while a marginal one will still cause you problems. let us know what you find out wrnch61 hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. it doesnt seem to make any difference whether the engine is cold or warm and there are no other drivability problems the idle is fine etc. no trouble codes are being set. due to the time element nature of the problem i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i have also read of similar problems being caused by the throttle position sensor or the crank position sensor but the fact that the engine will re-start immediately and that there are no other drivability issues and no trouble codes would seem to lead one away from these causes. any thoughts or pointers would be appreciated... - seth .
From : s miller
hi paul and twix thanks for your comments. i certainly dont doubt your experiences but i dont see how it would be possible for the fuel pump to be the culprit in my case. if i turn the ignition to on without starting i can hear the fuel pump run for a few seconds and then shut off as soon as the fuel rail comes up to the proper pressure just as it is supposed to do. if i try to start the engine at that point i will still experience the hard starting problem even though the fuel pressure is up to normal. and as i mentioned earlier the dc service manual states that it is not even necessary for the fuel rail to maintain pressure in order to provide a normal start. again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. - seth twix wrote i agree. i had the same same problem same solution. the fuel pump originally shipped with these trucks had some know issues. i had to replace mine twice. dc redesigned the fuel pump because of the number of problems being fixed under warranty but there is no recall or tsb for this. on thu 23 oct 2003 134821 gmt paul johnson thejohnsons@frontiernet.net wrote hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. ... ...i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i had this problem with my 95 v-10. it turned out to be a defective fuel pump- was allowing fuel to bleed back. new fuel pump under warranty fortunately completely solved the problem. paul johnson .
From : prowler99s miller
check out the new dodge ram 3500 quad x-tra large http//feisar.de/stuff/dodge.jpg randy .
From : tbone
what you might not be taking into account is air entering the fuel rail near the injectors. if that is happening then the truck will not start until the air is purged out through the injectors and that takes a little time. -- if at first you dont succeed youre not cut out for skydiving hi paul and twix thanks for your comments. i certainly dont doubt your experiences but i dont see how it would be possible for the fuel pump to be the culprit in my case. if i turn the ignition to on without starting i can hear the fuel pump run for a few seconds and then shut off as soon as the fuel rail comes up to the proper pressure just as it is supposed to do. if i try to start the engine at that point i will still experience the hard starting problem even though the fuel pressure is up to normal. and as i mentioned earlier the dc service manual states that it is not even necessary for the fuel rail to maintain pressure in order to provide a normal start. again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. - seth twix wrote i agree. i had the same same problem same solution. the fuel pump originally shipped with these trucks had some know issues. i had to replace mine twice. dc redesigned the fuel pump because of the number of problems being fixed under warranty but there is no recall or tsb for this. on thu 23 oct 2003 134821 gmt paul johnson thejohnsons@frontiernet.net wrote hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. ... ...i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i had this problem with my 95 v-10. it turned out to be a defective fuel pump- was allowing fuel to bleed back. new fuel pump under warranty fortunately completely solved the problem. paul johnson .
From : miless miller
abe wrote i have a 97 ram 1500 and a 96 plymouth voyager minivan. im getting ready to sell or trade the van and the only thing wrong with it is the same infinity setup thats in my truck. ive had thoughts of replacing the van radio with the truck radio and buying something after-market for the truck. i know the infinity setup has some special amps or something somewhere that complicate buying an after-market replacement. does anyone know the real scoop on replacing the infinity head with something else i have a 2001 1500 qc with the infinity speakers. very easy to swap out the stock head unit with an aftermarket. the infinity speakers each have their own small amp but are designed to accept high level amplified signals. the only thing you need to look for in a replacement head unit is to make sure it has a remote amp wire. almost all but the very cheapest head units do. this wire will turn on all of the infinitys small amps whenever your trucks radio is on. buy a wire harness from your local car stereo store or even walmart. runs about $15 or less and really makes wiring simple. .
From : redneck tookover hell
again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. a simple test is to cycle the key several times without engaging the starter from off to on when the vehicle has sat for at least several hours. if it starts right up after the last cycle its the fuel pump if not then its something else ill start watching reality tv shows when i can vote people off the planet. .
From : s miller
hmmm yep... good point... and i think youre right... see my response to redneck below... tbone wrote what you might not be taking into account is air entering the fuel rail near the injectors. if that is happening then the truck will not start until the air is purged out through the injectors and that takes a little time. -- if at first you dont succeed youre not cut out for skydiving hi paul and twix thanks for your comments. i certainly dont doubt your experiences but i dont see how it would be possible for the fuel pump to be the culprit in my case. if i turn the ignition to on without starting i can hear the fuel pump run for a few seconds and then shut off as soon as the fuel rail comes up to the proper pressure just as it is supposed to do. if i try to start the engine at that point i will still experience the hard starting problem even though the fuel pressure is up to normal. and as i mentioned earlier the dc service manual states that it is not even necessary for the fuel rail to maintain pressure in order to provide a normal start. again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. - seth twix wrote i agree. i had the same same problem same solution. the fuel pump originally shipped with these trucks had some know issues. i had to replace mine twice. dc redesigned the fuel pump because of the number of problems being fixed under warranty but there is no recall or tsb for this. on thu 23 oct 2003 134821 gmt paul johnson thejohnsons@frontiernet.net wrote hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. ... ...i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i had this problem with my 95 v-10. it turned out to be a defective fuel pump- was allowing fuel to bleed back. new fuel pump under warranty fortunately completely solved the problem. paul johnson .
From : s miller
bingo. cycling the ignition and thus the fuel pump through a few cycles rather than just once as i had been trying will result in the engine starting normally... thanks much for the tip and also thanks to the others who suggested the fuel pump or a fuel-related problem as it looks as though you were all on the mark. ill try this test again through a few more cold start cycles and if the results hold up then i guess ill let the dealer take a look at it because it looks like the culprit could actually be many things... check valve in the fuel pump check valve in the pressure/regulator maybe just a leaking injector i hope and some of these parts are pretty expensive and thus maybe not such a good idea to shotgun this one. maybe ill get a fuel pressure gauge and one of those adapter rigs that goes between the fuel line and fuel rail so i can isolate the problem in one direction or the other... if its just a leaky injector i can take care of that one pretty easily myself. would not look forward to dropping the tank... damn i remember when the fuel pump was mounted right on the front of the engine and cost $12.95 at pep boys... redneck tookover hell wrote again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. a simple test is to cycle the key several times without engaging the starter from off to on when the vehicle has sat for at least several hours. if it starts right up after the last cycle its the fuel pump if not then its something else ill start watching reality tv shows when i can vote people off the planet. .
From : roy
damn red ya saved another!! see what happens when ya get off the machine bfg roy bingo. cycling the ignition and thus the fuel pump through a few cycles rather than just once as i had been trying will result in the engine starting normally... thanks much for the tip and also thanks to the others who suggested the fuel pump or a fuel-related problem as it looks as though you were all on the mark. ill try this test again through a few more cold start cycles and if the results hold up then i guess ill let the dealer take a look at it because it looks like the culprit could actually be many things... check valve in the fuel pump check valve in the pressure/regulator maybe just a leaking injector i hope and some of these parts are pretty expensive and thus maybe not such a good idea to shotgun this one. maybe ill get a fuel pressure gauge and one of those adapter rigs that goes between the fuel line and fuel rail so i can isolate the problem in one direction or the other... if its just a leaky injector i can take care of that one pretty easily myself. would not look forward to dropping the tank... damn i remember when the fuel pump was mounted right on the front of the engine and cost $12.95 at pep boys... redneck tookover hell wrote again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. a simple test is to cycle the key several times without engaging the starter from off to on when the vehicle has sat for at least several hours. if it starts right up after the last cycle its the fuel pump if not then its something else ill start watching reality tv shows when i can vote people off the planet. .
From : wrnch61
perhaps restricted exhstcat convtr o2 sensor air control valve. each react to temp. changeseither directly or indirectly the codes often will not show up til a sensor is completely bad while a marginal one will still cause you problems. let us know what you find out wrnch61 hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. it doesnt seem to make any difference whether the engine is cold or warm and there are no other drivability problems the idle is fine etc. no trouble codes are being set. due to the time element nature of the problem i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i have also read of similar problems being caused by the throttle position sensor or the crank position sensor but the fact that the engine will re-start immediately and that there are no other drivability issues and no trouble codes would seem to lead one away from these causes. any thoughts or pointers would be appreciated... - seth .
From : paul johnson
hi all i have a 2001 dakota 4.7/auto with 42k miles that has always started immediately anytime warm or cold. recently however i have needed fairly long cranking times to get the engine started whenever the vehicle has not run for a few hours or more. once started with a long cranking run i can immediately shut off the engine and it will restart normally immediately until the engine has set for several hours then again a long cranking period will be required to get it started. ... ...i first thought that this might be due to the fuel pressure leaking down too quickly due to a leaky injector or check valve but a look at the service manual reveals in bold type no less that a fuel pressure of zero in the fuel rail is perfectly normal for a cold engine so it would appear that fuel pressure leakdown is not the cause of the problem. i had this problem with my 95 v-10. it turned out to be a defective fuel pump- was allowing fuel to bleed back. new fuel pump under warranty fortunately completely solved the problem. paul johnson .
From : jim
i found these postings very interesting. my 97 3.9l 57000 mile dakota has occasionally required longer cranking to start. it started doing this about 18 months ago. not a problem since it rarely occurred. a new distributor cap seemed to eliminate the problem for a while. however the last couple of weeks after a 700 mile trip it has gotten very frequent hot or cold day or night recent start or no recent start. i took it to goodyear and they said everything is okay within spec -- might be carbon build up absorbing the initial fuel load. i pulled a plug and it looked fine. the ignition wire ends look good. i do about 1/2 highway driving and 1/2 local driving. does anyone have any suggestions please post response since my mailbox is full of trash spam and i dont dare go near it. tia. jim damn red ya saved another!! see what happens when ya get off the machine bfg roy bingo. cycling the ignition and thus the fuel pump through a few cycles rather than just once as i had been trying will result in the engine starting normally... thanks much for the tip and also thanks to the others who suggested the fuel pump or a fuel-related problem as it looks as though you were all on the mark. ill try this test again through a few more cold start cycles and if the results hold up then i guess ill let the dealer take a look at it because it looks like the culprit could actually be many things... check valve in the fuel pump check valve in the pressure/regulator maybe just a leaking injector i hope and some of these parts are pretty expensive and thus maybe not such a good idea to shotgun this one. maybe ill get a fuel pressure gauge and one of those adapter rigs that goes between the fuel line and fuel rail so i can isolate the problem in one direction or the other... if its just a leaky injector i can take care of that one pretty easily myself. would not look forward to dropping the tank... damn i remember when the fuel pump was mounted right on the front of the engine and cost $12.95 at pep boys... redneck tookover hell wrote again im not doubting your experience and im not trying to debate anything or say that youre wrong but it seems that in my case it is very unlikely that low fuel pressure could possibly be the problem. a simple test is to cycle the key several times without engaging the starter from off to on when the vehicle has sat for at least several hours. if it starts right up after the last cycle its the fuel pump if not then its something else ill start watching reality tv shows when i can vote people off the planet. .