96 SLS sometimes hard to start
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Northstar Engines and System Technical Discussion Discussion, 96 SLS sometimes hard to start in Cadillac Engine Technical Discussion; I posted this once before to no responses, so I'm trying again. The car sometimes, probably 75% of the time, ...
  1. #1
    mcowden is offline Cadillac Owners Connoisseur
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    Unhappy 96 SLS sometimes hard to start

    I posted this once before to no responses, so I'm trying again. The car sometimes, probably 75% of the time, cranks 5-10 seconds before starting. The rest of the time, it starts just perfectly after about 1 second. I didn't see anything leaking from the FPR. Once started, it runs just fine. No misfires, etc. and there are no codes. I have noticed the gas mileage has gone down probably 10-15%, to 15 from an average of about 17 previously. I do almost all in-town, heavy traffic driving, so I expect it to be low, but it's lower than normal. Could this be a dirty injector leaking? If I take them out one at a time, will I be able to tell by looking at them whether they need cleaning? How do I take them out with the stainless fuel rail? Maybe an IAC? The idle speed is fine, though, so I don't think that's the case. Anything else I should be looking at or suspecting? Should I just go ahead and replace the FPR? Can they have intermittent leaks? (I don't think so, but I also recognize that I'm not the foremost expert at anything)

    Many thanks in advance for any thoughts or advice... If you're in the Chicago western 'burbs, stop by and I'll buy ya a beer.
    Mike

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  3. #2
    EcSTSatic's Avatar
    EcSTSatic is online now Cadillac Owners Connoisseur
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    Re: 96 SLS sometimes hard to start

    http://cadillacforums.com/forums/showthread.php?t=41332

    This sounds different from your last starting problem. What do your plugs look like? Wet? Do you smell fuel? Have you measured your fuel pressure to see if it's in specs?
    Maybe it's a timing problem, I'm thinking crank sensors.
    Have you pulled your codes?

  4. #3
    mcowden is offline Cadillac Owners Connoisseur
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    Re: 96 SLS sometimes hard to start

    Quote Originally Posted by EcSTSatic
    http://cadillacforums.com/forums/showthread.php?t=41332

    This sounds different from your last starting problem. What do your plugs look like? Wet? Do you smell fuel? Have you measured your fuel pressure to see if it's in specs?
    Maybe it's a timing problem, I'm thinking crank sensors.
    Have you pulled your codes?
    I haven't looked at the plugs yet. I'll get that done this weekend. The problem is the same now as it always has been. Nothing has become better or worse. I have also not checked the fuel pressure, but I think I will invest in the gauge and do the check. I would think crank sensors would cause other symptoms or set a code. There are no codes other than the P0603 that sets when you disconnect the battery. I disconnected it for a minute to try and reset any stored values that might be causing a problem, but that had no effect on anything. The car seems to run just fine at all speeds. It's only starting and the decreased mileage that's weird. I appreciate the response!
    Mike

  5. #4
    mcowden is offline Cadillac Owners Connoisseur
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    Re: 96 SLS sometimes hard to start

    Wondering if anyone thinks I ought to look at the injectors. Maybe I've got a leaky one? Or should I just go ahead and replace the FPR? How do you get the stainless fuel rail off there to check the injectors? Should I clean the EGR while I'm in there? Sorry to be a pest, I just need to have this thing running well because I depend on it. Thanks in advance for any and all ideas.
    Mike

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    Re: 96 SLS sometimes hard to start

    Cleaning the EGR would be a good place to start. It's not going to be easy to get it off with the SS fuel rail in place. Since you may have to disconnect the fuel rail anyway, that may be a good time to remove the entire rail with injectors still attatched. If you can lift it enough while still connected to the supply line, turn the key on to energize the pump and pressurize the fuel system while watching for a leaky injector. BTW, the system should hold pressure when shut down. You could put a pressure guage on it and watch it after you shut down. See if the pressure drops. If so, then you know there is a leak somewhere. As a discalimer I should mention that there is a check valve in the fuel pump that is supposed to keep the system pressurized after shut down. I have heard that these are known to fail so the leak down test is not always conclusive but would be a good place to start.

  7. #6
    mcowden is offline Cadillac Owners Connoisseur
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    Re: 96 SLS sometimes hard to start

    Thanks, Ranger, I'll give that a shot. I assume the injectors are sitting in grommets and just pull directly upward out of their spots so I can lift the whole mechanism by gently pulling at each injector. With the rail and injectors up, I should be able to get to that EGR a little easier and I might as well do it while I'm there, eh? (no, I'm not from Wisconsin) I'll let you know what I find, assuming I can buy a gauge tomorrow (Memorial Day).
    Mike

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    Re: 96 SLS sometimes hard to start

    Yeah, the injectors should be in rubber grommets or "O" rings and you should be able to lift the fuel rail and injectors in one unit.

  9. #8
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    Re: 96 SLS sometimes hard to start

    mcowden,

    what was the outcome of this problem? i have the same situation with the starting as you. dont know what could be causing it. thanks

  10. #9
    LukeChumley is offline Cadillac Owners Member
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    Re: 96 SLS sometimes hard to start

    My '95 Eldo did the same thing. I bought it used, and it needed new plugs and wires. Have you tried an average tuneup?

  11. #10
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    Re: 96 SLS sometimes hard to start

    i bought mine used too. at a 132k now has 134k. the owner said he replaced the plugs and wires. the plugs looked like they have been replaced. plugs cant really tell without taking them out.

  12. #11
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    Re: 96 SLS sometimes hard to start

    Have you checked for a leaking FPR? That will cause hard hot starts.

  13. #12
    J.A.O. is offline Cadillac Owners Fanatic
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    Re: 96 SLS sometimes hard to start

    Ranger, is the bad FPR most noticed when the engine is warm? My car (96 ETC 93000 miles) is getting harder to start lately when it's warm and after it starts, the rpms drop to where the engine almost stalls, and fluctuate for a few seconds then smooth out. From what I recall, the engine starts fine when it's cold. How much to replace the FPR at a dealer????

  14. #13
    Ranger's Avatar
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    Re: 96 SLS sometimes hard to start

    Yes, a leaky FPR will be more evident with hot starts. If the diaphram is bad it will leak raw gas into the intake manifold when shut down til the fuel pressure is relieved thus causing a rich start condition. Somewhat like starting a carburated engine with a closed choke, aids in cold starts but hampers hot starts. No idea on dealer prices as I do my own mantainence but it is very easy to diagnose and change. Locate the FPR on the right (rear) fuel rail under the silver beauty cover. It is a small canister looking device with a vacuum hose on the top. With the engine running, pull the vacuum hose and plug it with your thumb to close the vacuum leak you just created and look for fuel leaking from the nipple. There should be none. If there is, get a new FPR. Locate the schreader valve on the opposite rail. Remove the cap, put a rag over it and depress the valve (just exactly like letting air out of a tire). You may get an ounce of gas out of it but with a bad FPR maybe none. Pull the retaining clip on the FPR, pull the FPR and replace with the new one. Lube it with a little engine oil before instalation to ease in seating it in the "O" ring. Pay attention to the "O" ring, that's what seals it. That's all there is to it. I'm guessing the dealer would get every bit of $100 or more.

  15. #14
    eldorado1 is offline Cadillac Owners Connoisseur
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    Re: 96 SLS sometimes hard to start

    Quote Originally Posted by Ranger
    Locate the schreader valve on the opposite rail. Remove the cap, put a rag over it and depress the valve (just exactly like letting air out of a tire). You may get an ounce of gas out of it but with a bad FPR maybe none. Pull the retaining clip on the FPR, pull the FPR and replace with the new one. Lube it with a little engine oil before instalation to ease in seating it in the "O" ring. Pay attention to the "O" ring, that's what seals it. That's all there is to it. I'm guessing the dealer would get every bit of $100 or more.
    With the engine OFF of course.

    Don't want to look like this (minus the grin):

  16. #15
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    Re: 96 SLS sometimes hard to start

    Engine doesn't need to be OFF on the '95+. Any fuel leakage will be minor and the vacuum hose can be quickly reinstalled. '93-'94 is another story and should NEVER be started with the intake cover off.

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