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  1. #1

    Default 1994 Suburban not starting, stalled?

    Hello everyone,

    I just purchased a 94 Suburban, 145k miles. Original owner said it ran great aside from a leaky radiator and the occasional hard shifting, but inexplicably stalled last week when she tried to move it to her driveway, she couldn't get it started and sold it to me. I tried shooting starting fluid into the throttle body and after many attempts, it fired up and idled fair -- the starting fluid didn't provide much help. I put it in gear after letting it warm up for awhile, tried to move it, but it stalled. I started it again, put it in gear and it pulled, I drove around the block gently. Near the end I gave it a little bit more gas then before, and again it stalled. This time I tried revving it in neutral, i got it to 3500RPM and let go - thinking it was fine. I proceeded to give it another quicker rev and this time it sounded similar to a backfire
    as it struggled to keep running, but couldn't, and a small plume of smoke came out of the top engine as it shut off -- it only made it to 1200rpm before turning off. It won't start anymore, but I have not added more starting fluid as the battery is dead. I don't have much money to replace many parts on it, but what is the most likely cause of this? Is it possibly the fuel injector needs replacing? Is it a bad Cat or incorrect timing (wouldn't it not idle fair at all then?)? ECM? MAF sensor? The wires look good but I haven't checked the plugs, but I assumed the spark was fine since it was idling fine. I checked an old Haynes manual and can't find a solid answer...

    Every bit of help is GREATLY appreciated - I cannot afford to bring it to a shop right now, especially with a tow.

    Thanks and Merry Christmas,
    Nick

  2. #2
    Master Mechanic Jimmeh's Avatar
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    Default

    Well, it could be so many things that the list could be a mile long. Is it giving you a check engine light? If it is, the best thing to do would be to take it to your local auto parts store and hook it up to their code reader(most O'Reilly's, Advance Auto, or Auto Zone's should have them for both OBD I and OBD II). Just in recent experience, I wouldn't say it is your catalytic converter because you never mentioned anything sounding like it was sucking air, but that doesn't mean that isn't the problem. If the MAF is starting to go, spraying electronics cleaner solution into the plug ends could be a short term remedy to help diagnose the problem further.

    In my personal opinion, it almost sounds like it is starving for fuel. Whether that could be from a pinched line, clogged fuel filter, bad injector, etc. it's hard to tell. I am hoping that it is throwing a code at you so you might be able to help us out and tell us which one it is. Keep us posted if you do happen to find an issue.
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  3. #3
    Sr. Engineer
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    Sounds fuel related for sure ... starving for fuel backfire. Might be as simple as a dirty fuel filter.
    But as stated above does it have a check engine light. If so can check for codes by jumping pins a&b on diagnostic port
    at driver side under dash . Will see a rectangle port with ports/pins jump a&b with a paper clip or wire.
    Turn key to on position .. check engine light will start flashing .. will flash once.. short pause... will flash twice .
    Will be a 12 means ecm/ computer is ready and working. Then watch close will start flashing codes if any stored. Exsample
    Flash 3 times.. short pause two flashes means code for egr. and so on. Your truck does not have a maf sensor 96 up.
    Can check fuel pressure at back of throttle body inlet line or at filter. Will have to buy a gauge 22 bucks or borrow one from auto parts store some have loan a tool. When you try to crank does fuel flow from injectors? When it is idling does it seem to have a fan like pattern at injectors?
    Will have to get one with a tee adapter . Pressure should be 9 to 14 psi.

  4. #4

    Default

    Thanks for the quick responses. I replaced the fuel filter and fuel came out so I am assuming the fuel pump is OK, and I heard it working.
    Last edited by Nick72; 12-14-2011 at 11:42 PM.

  5. #5

    Default

    I attempted to start it this morning, it made a very loud backfire sound and now it won't even sound like it is getting close to starting. The computer was throwing a code 54 and I replaced the fuel pump relay and it stopped. I can see fuel at the injectors but it is still not starting, and now it doesnt seem like it even wants to, as it did before. Is it spark related? The plugs look somewhat old but since it started before and I got it to high RPMS I don't think it is. I am at a loss, should I just start replacing sensors in this order: TPS, MAP Sensor and O2 sensor?

    Again help is greatly appreciated...

    thanks

  6. #6
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    Not yet.. check for spark at plugs ... if not any pull coil wire off of dist cap see if spark there.
    If not ... injectors are firing so would not think ignition module. Maybe the coil. Do you have a electrical meter.. and can use one?
    Let us know ..will tell you how to check some things ..instead of buying parts.
    Will check back tomorrow... check for spark rule that out . Can take plug out stick back in plug wire lay on intake or exhaust manifold should get a good bluish spark. While turning engine over. Do this also ..take injectors loose as not to flood while checking things. Just grab the clip and squeeze.. pull up.
    to disconnect .

  7. #7

    Default

    Quote Originally Posted by dipstick View Post
    Not yet.. check for spark at plugs ... if not any pull coil wire off of dist cap see if spark there.
    If not ... injectors are firing so would not think ignition module. Maybe the coil. Do you have a electrical meter.. and can use one?
    Let us know ..will tell you how to check some things ..instead of buying parts.
    Will check back tomorrow... check for spark rule that out . Can take plug out stick back in plug wire lay on intake or exhaust manifold should get a good bluish spark. While turning engine over. Do this also ..take injectors loose as not to flood while checking things. Just grab the clip and squeeze.. pull up.
    to disconnect .
    I can buy and electrical multimeter, and I will check for spark at plugs tomorrow since its already dark.
    I will post back sometime tomorrow.

    Thank you

  8. #8

    Default

    I am pretty sure you need a distibutor. The only other thing could be the ESC module or the actual PCM. Try undoing the ESC plug on the wiring harness behind the cover for the relays on the passenger firewall side. It is a single tan wire plug where you see the harness starting to turn down toward the distributor. That will set it in base timing mode. It might idle a little funny but if you can rev it and drive it with out it missing it is more than likely a electronic spark control (ESC) problem.

  9. #9

    Default

    Quote Originally Posted by johnb9173 View Post
    I am pretty sure you need a distibutor. The only other thing could be the ESC module or the actual PCM. Try undoing the ESC plug on the wiring harness behind the cover for the relays on the passenger firewall side. It is a single tan wire plug where you see the harness starting to turn down toward the distributor. That will set it in base timing mode. It might idle a little funny but if you can rev it and drive it with out it missing it is more than likely a electronic spark control (ESC) problem.
    John, if the ESC/knock sensor was the problem wouldn't it throw code 43: "The ECM did not detect a knock signal during near wide open throttle operation with coolant temperature above 194 F or the knock signal was present for 5 seconds or more during normal engine operation. Electronic Spark Control (ESC) Circuit."

  10. #10

    Default

    Due to the fact I need my vehicle functional as soon as possible I went ahead and checked for spark on one of the plugs right now at 1AM here, lol. The spark plug looks like it definitely needs replacing, but ive seen worse. I am not getting spark to the plug, however it was cranking on a near dead battery at 6-7 volts, and it was just clicking, would this make a difference?

    Also John, when you say I need a new distributor, you mean the distributor cap right? I have no money to replace the entire distributor shaft since it is so costly... And since it got to 5,000 RPM okay before, doesn't that mean the distributor isn't in need of replacement?

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