94 Deville won't start
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HT4100 4.1, 4.5, 4.9 Discussion, 94 Deville won't start in Cadillac Engine Technical Discussion; I have the following codes: P031(h), P048(c), P061(h), P098(h), A047(c), I039(C) I parked in the garage upon returning from 1/2 ...
  1. #1
    TheeSlowPoke is offline Cadillac Owners Member
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    94 Deville won't start

    I have the following codes:
    P031(h), P048(c), P061(h), P098(h), A047(c), I039(C)

    I parked in the garage upon returning from 1/2 hour drive. After a few minutes tried to start it back up, and it would not start - it would just spin over. It tried to start, but wouldn't hit more than a couple cylinders in a row. Checked vacuum lines and found one cracked. Replaced the line and it started.

    Left it sit over night. Next day it started and I drove it 35 minutes each way to and from work - no problem. Stopped in the driveway and shut it off. Went to start it a few minutes later to pull into the garage - no go. It just spins over and doesn't even try to start. Doesn't matter if I floor it or leave the pedal alone.

    I checked the MAP sensor to the point of applying vacuum to it, but I don't have a vacuum pump and am not sure I want to spring for a $135 tool that I may never use again. The P031 and P098 are the only codes that are new. The A047 code just came in a week ago - my 1 1/2 year old reman A/C compressor is leaking. All the others have been around for quite a long time. I replaced the EGR valve and cleaned the tubes a year, or so, ago, but the P048 didn't go away. I was thinking the P048 may have been due to the cracked vacuum line I just found, but it is still current. The fact that it tried to start yesterday makes me think it is fuel related. But with no attempt to fire today, I am not so sure.

    Can you guys give me some direction as to where to start with my trouble shooting efforts? It is cold out there, so I would like to be on the right track.

    Thanks for your help!

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    kdcing is offline Cadillac Owners Fanatic
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    Re: 94 Deville won't start

    ....hhmmmm....from your description, both no-starts were under hot engine conditions (the 1st no-start may or may not have been fixed by the vacuum line replacement).

    P031 seems to target the MAP, but a I do not believe a bad MAP would cause a no-start...I believe the engine would run, but may run like crap. Check the value of PD02. If it is 103-105, unplug the MAP. If PD02 drops to 10-16, the MAP or its wiring is suspect.

    Before replacing anything, I would clear the codes and see which ones come back. I would also prove out the idea that it is a hot condition issue. Have a fuel pressure guage on hand (Autozone has them in their freebie loaner program) when you get back from the 15-20 minute drive.

  4. #3
    FrankC's Avatar
    FrankC is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    I suppose you are sure you are getting good spark? Ignition module failures can be intermittant like you describe. And you can get them checked at Oreillys on their machine. There are perhaps 6 different stages of checks that are made.

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    TheeSlowPoke is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    Thanks for the responses.

    The car will not start, at all - whether cold or hot. It is still sitting in my driveway, which is at an upward slope so I cannot push it in the garage. At least it stalled at home, both times. It spins over. It has good spark. I will check fuel pressure.

    The PD02 is 99 and after unplugging the MAP, it stays at 99. So, the MAP won't keep it from starting - shoot, I was hoping for something simple. :<(

  6. #5
    HUF's Avatar
    HUF
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    Re: 94 Deville won't start

    Can you hear the fuel pump for a couple of seconds when you turn ignition ON (engine is oFF)? The sound comes from the fuel tank. Spay some starting liquid in TB to see if it starts that way. If it does, something wrong with the fuel delivery system.

  7. #6
    kdcing is offline Cadillac Owners Fanatic
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    Talking Re: 94 Deville won't start

    Quote Originally Posted by TheeSlowPoke View Post
    - shoot, I was hoping for something simple. :<(
    The problem will be simple (i.e. lack of Fire, Fuel or Air), finding it and fixing it could be the difficult part.

    As Huf mentioned, listen for the fuel pump to run for 2-3 seconds when the ignition key is turned on (engine off). On my Eldorado, the FP gives a distinct high-pitched whine which is audible from the driver's seat...others have suggested to remove the gas tank cap, put your ear to the tank and then turn the key.

    If you have a Fuel Pressure guage (available in AutoZone's freebie tool loaner program), 40-50psi are needed. Another poster reported a no-start condition w/ 35psi...and got it running again w/ a new FP.

  8. #7
    TheeSlowPoke is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    The problem appears to be fuel related. Verified by pouring gas into the throttle body and then trying to start it. The car started and ran. It has started several times since without pouring any gas in the throttle body, too. Each time I have tried to start it, except for this morning, the fuel pump "does" run for a couple seconds upon turning the ignition on.

    I don't recall hearing the fuel pump the times the car didn't start. I suspect the fuel pump, but don't know why it would work perfectly at times and other times won't work, at all. I didn't get a chance to pick up a fuel pressure gauge due to the holiday weekend. The fuel pump didn't run this morning when I turned on the ignition, but the car "did" start.

    If I check the fuel pressure and it is good, does that point to the fuel pump relay, or still the fuel pump? According to the manual, the fuel pump relay should set a PCM trouble code if it doesn't work. I'll follow the fuel pressure check, maybe it will be clear what needs to be done when I actually check the pressure.

  9. #8
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 94 Deville won't start

    How old is the fuel filter? These cars also don't seem to like running on less than 1/4 tank of fuel.

  10. #9
    kdcing is offline Cadillac Owners Fanatic
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    Re: 94 Deville won't start

    ...could be the relay also. You may find that the relays for the headlights and the FP are the same Omron relays (check PN and/or markings on the side of the relay). If they are the same (they are the same on my '93 Eldo), swap them and see if the headlights go intermittent and the FP becomes good. I've seen others indicate that simply removing and reseating the relay will knock off 14 years of corrosion and improve the electrical contact.

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    TheeSlowPoke is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    Finally got around to getting a fuel pressure tester. I only have 30 psig while/after the pump runs - it doesn't sound like it used to, either. I am sure the fuel pump is the problem.

    New question??? What else, besides the fuel pump, do I need to replace the fuel pump? Is the gasket re-useable? Or, do I need to get a new one of those, too.

    Does $278 for an A-C Delco sound OK? That is from Rock Auto.

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    1stL is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    I think you get a new gasket (tank seal) with the new unit. I paid $300 for my pump from CarQuest because I had to have it right away. Your price from RockAuto sounds good plus it's an AC Delco unit. I've always heard that you should go OEM for alternators, starters, and fuel pumps. I noticed that their site shows 2 different AC Delco models for your application. Now that I think about it, I had to drop my tank down to get the part number off of the top of the pump and that's why I got it locally. Mine was the more expensive unit. I changed my fuel filter at the same time.

  13. #12
    kdcing is offline Cadillac Owners Fanatic
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    Re: 94 Deville won't start

    Quote Originally Posted by TheeSlowPoke View Post
    New question??? What else, besides the fuel pump, do I need to replace the fuel pump? Is the gasket re-useable? Or, do I need to get a new one of those, too.

    Does $278 for an A-C Delco sound OK? That is from Rock Auto.
    Inside the fuel tank, the fuel pump sits inside of a round plastic contraption which includes the fuel float and sending unit. At $278, you are probably getting both the FP + sending unit/float. The FP (w/o sending unit or float) costs $80 @ AutoZone....the sending unit and float are reusable as long as they are operational and none of the plastic housing breaks during disassembly/reassembly.

    There are 3 filters.....2 in the fuel tank (these are referred to as "strainers") + 1 outside the tank underneath the car (on my Eldorado it is tucked underneath the rocker panel, just behind the rear edge of the driver's door). The 2 in-tank strainers should be replaced when replacing the FP.....1 strainer is connected to the bottom of the FP (which sits inside the "plastic cup" of the sending unit)....the 2nd strainer is installed on the exterior/bottom of the plastic cup. The fuel filter underneath the car should also be replaced but can be done at any time.

    The gasket is of a semi-hard plastic material (not rubber) and can be reused if not cracked (if you go w/ the FP + sending unit, the gasket is likely included).

    Btw....don't forget to relieve the fuel pressure in the gas lines before disconnecting the fuel line at the tank (i.e. pull the fuse for the fuel pump and crank the engine until the fuel pressure guage drops)

    These 2 posts may help out:
    http://www.cadillacforums.com/forums...tructions.html

    http://www.cadillacforums.com/forums...ad-fuel-2.html

  14. #13
    AL Deville's Avatar
    AL Deville is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    Not much help now..or should I say does`nt matter...but auto zone does`nt loan out fuel pressure gauges anymore...
    not near where I live anyway..flint michigan area..
    I tried to get one to test my fuel pressure recently, and called several auto zone locations..all said they dont loan them out anymore....bummer..

    AL

  15. #14
    FrankC's Avatar
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    Re: 94 Deville won't start

    I just bought a fuel pressure gauge a week ago or so from Harbor Freight. It was $14. Came with fuel line and adapters to fit various fittings such as the Shrader valve on the gas line.

  16. #15
    TheeSlowPoke is offline Cadillac Owners Member
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    Re: 94 Deville won't start

    I bought the fuel pressure gauge set, <$30.

    Didn't know which pump assembly I had, so obtained an EPT from a wrecking yard, a new 2nd design assembly and a new pump for the EPW assembly. Had all the bases covered.

    Dropped the tank and found an EPW assembly in the tank. Didn't want to pay the price the dealer wanted for the new 2nd design assembly plus didn't want to open it to find out if it has the same number of lines for fear the dealer wouldn't take an opened package back. The EPT has 3 lines coming out of the assembly whereas the EPW has only two lines. Only choice available was to replace the pump within the assembly. Paid $120 for the new pump. Unfortunately, they didn't have the external strainer. Didn't want to wait - so, back in with the old external strainer. It runs good, once again. Back on the road for <$150 (plus some less than enjoyable hours under the beast).

    Will return the new assembly to the dealer and the used pump to the wrecking yard.

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