Northstar - Starting Problems
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Northstar Engines and System Technical Discussion Discussion, Northstar - Starting Problems in Cadillac Engine Technical Discussion; I have a '98 Concours and can't seem to find source of hard starting problem. Turns over for several seconds ...
  1. #1
    rslanca is offline Cadillac Owners Member
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    Northstar - Starting Problems

    I have a '98 Concours and can't seem to find source of hard starting problem. Turns over for several seconds before it fires. Anyone else experienced this problem or have an idea what's causing it?

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    sts96 is offline Cadillac Owners Fanatic
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    Re: Northstar - Starting Problems

    Hard start warm engine fuel pressure regulator leaking into vacuum line and intake, hard start cold engine low fuel pressure from pump. check for codes could be many other things. sts96

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    sseville is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    I have a similar problem as you do. As the colder weather moves in and I have the heater going for awhile and then shut the car off it dosen't want to start at all. What happens is it'l take much longer than usual cranking time and then when the engine fires it'l only fire for a second or two then stall. Usually it does this twice at which point I give it a little gas and even still the rpm's drop below 500 once or twice until I rev it up a couple times..........Just odd to say the least.

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    lonestar is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    I have a hard start when the engine is hot does anyone have any ideas

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    Re: Northstar - Starting Problems

    Quote Originally Posted by lonestar
    I have a hard start when the engine is hot does anyone have any ideas
    Check the FPR. Pull the vacuum hose off while the engine is running. If fuel leaks out of the nipple, replace FPR. If not FPR, then leaky injector(s).

  7. #6
    exuberant anti-spam is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    What does FPR stand for?

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    Re: Northstar - Starting Problems

    FPR = fuel pressure regulator. It is mounted on the right bank (rear) fuel rail.

  9. #8
    ebs007 is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    I have the same problem with my 97 STS. It starts fine cold, and usually starts ok if it's still hot (shut off within 10-20 minutes) but hard to start when warm. It will crank for a while, sometimes backfire, then eventually start. It starts better if I give it a little gas while cranking. I'll have to check for the leaky FPR ... thanks for the tip! :coolgleam:

  10. #9
    longisland516 is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    I have a hard start with a 97 DeVille. This car currently has 118k. FPR, plugs, wires, and coil packs/module have been replaced and the car starts the same.

    The car starts hard cold, below 30F. It cranks and seems like it is firing on one or two cylinders. I have to keep the starter on to prevent it from stalling once it starts to fire. This whole process is about 8 seconds. Sometimes it will stall. The computer usually increase the idle a lot just before the stall to try and compensate.

    The fuel pumps runs for about 2 seconds when I turn on the key and everything seems to be fine. Sometimes it will miss on one or two cylinders for about 1 minute or until engine temperature reached about 40 degrees. The car always seems to start, even when the temp is 0F. It has had this condition for the last year and 18k miles.

    The car runs 100% perfect after this and runs perfectly smooth with no hesitation. Fuel economy is 23.6 mpg average for the entire last year. It runs 0-60 in 6.4 seconds and sounds great doing it. There are no codes set and have been none for the last year.

    Any ideas as to why this car starts hard when cold?

  11. #10
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Northstar - Starting Problems

    I'm not saying this is the source of anybody's starting issues here, but I'm just sharing the anecdote because the difference was surprising.

    I changed out plugs and wires at 90k because of a misfire problem that was getting worse. I used the AC Delco 41-950 plugs and AC Delco wires as recommended passionately on these forums. The plugs that were in there were Bosch. I can't say I really had any serious starting problems with the car, but it did take some crank time, especially in cold weather, before the tune-up. Since doing the tune-up, it starts almost instantly, even when the temp is near 0F. The difference is amazing to me. I can't say it was the plugs or it was the wires because I changed both, but I'll tell you, I was really surprised by the difference.

    Maybe that'll help somebody. I won't use anything but the AC Delco wires and plugs in the future. Yeah, it was a few bucks more, but so far it was worth every penny. Best prices I found for them was at www.rockauto.com. The wireset was about $116 I think and the plugs were $5.89 each.

    The fuel pressure regulators can be tested. Take off the vacuum line going to the FRP and idle the engine for a few minutes. If you see fuel seeping from the vacuum nipple on the FPR, the diaphragm is bad and the FPR needs to be replaced. That will solve some hot restart problems.

    Good luck one and all... Check your codes and let us know the details of the problems and somebody will likely be able to help you fix it up.
    Mike

  12. #11
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    Re: Northstar - Starting Problems

    Quote Originally Posted by longisland516
    I have a hard start with a 97 DeVille. This car currently has 118k. FPR, plugs, wires, and coil packs/module have been replaced and the car starts the same.

    The car starts hard cold, below 30F. It cranks and seems like it is firing on one or two cylinders. I have to keep the starter on to prevent it from stalling once it starts to fire. This whole process is about 8 seconds. Sometimes it will stall. The computer usually increase the idle a lot just before the stall to try and compensate.

    The fuel pumps runs for about 2 seconds when I turn on the key and everything seems to be fine. Sometimes it will miss on one or two cylinders for about 1 minute or until engine temperature reached about 40 degrees. The car always seems to start, even when the temp is 0F. It has had this condition for the last year and 18k miles.

    The car runs 100% perfect after this and runs perfectly smooth with no hesitation. Fuel economy is 23.6 mpg average for the entire last year. It runs 0-60 in 6.4 seconds and sounds great doing it. There are no codes set and have been none for the last year.

    Any ideas as to why this car starts hard when cold?

    You really need to get a fuel pressure gauge on the rail and watch the fuel pressure DURING CRANK ON THE COLDSTART. If the fuel pump is starting to fail it will usually draw lots of current and will loose effectiveness when the system voltage is low....like during the cold crank when the starter is drawing the battery voltage (and fuel pump voltage) very low. It is not unusual to see 7 or 8 volts at the fuel pump during cold cranking so if the pump is weak at all it will just not put out..... The fuel pressure should pop up to about 50 and hold steady during crank.

    Try opening the throttle to see if that helps.

    To test for a rich condition causing a hard start warm/hot hold the throttle firmly to the floor before cranking and keep it firmly depressed when you crank. This enables clear flood and turns off the injectors. If the engine starts immediately then something is flooding the engine such as the FPR or a leaking injector.

  13. #12
    longisland516 is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    You guys were correct; the problem was the fuel pump. It finally failed at around 140k miles. Installed a new ACDelco and the car starts like the day it was new, at any temp.

  14. #13
    donclericuzio is offline Cadillac Owners Member
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    Re: Northstar - Starting Problems

    I have had the same problem and got it clarified when I was finally up to Cadillac to get my shinny new fuel rail!!! And also they replaced a airbag sensor as well!!! He calls me thought in the middle of the fix and tells me about the fuel pressure regulator,says total labor and part about 120$ anyways I didnt have the funds at the time to get it fixed!! So I was wondering if the leaking of the FPR could cause the rought engine idle, at stop lights it sometimes runs smooth at about 700rpms and sometimes surges all the way to like 1200-1300 with out touching the gas. It also sounds like maybe a timing problem posibly or maybe a vaccum hose?????!!!!?????

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    Ranger's Avatar
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    Re: Northstar - Starting Problems

    Quote Originally Posted by donclericuzio
    I have had the same problem and got it clarified when I was finally up to Cadillac to get my shinny new fuel rail!!! And also they replaced a airbag sensor as well!!! He calls me thought in the middle of the fix and tells me about the fuel pressure regulator,says total labor and part about 120$ anyways I didnt have the funds at the time to get it fixed!! So I was wondering if the leaking of the FPR could cause the rought engine idle, at stop lights it sometimes runs smooth at about 700rpms and sometimes surges all the way to like 1200-1300 with out touching the gas. It also sounds like maybe a timing problem posibly or maybe a vaccum hose?????!!!!?????
    I am not sure if a FPR would cause a rough or fluctuating idle or not, but you can get one for a lot less than $120. They are easy to diagnose and change (see Tech Tips section).

  16. #15
    Zorb750 is offline Cadillac Owners Connoisseur
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    Re: Northstar - Starting Problems

    FPR can cause odd idle patterns. It did on the Eldorado.

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