1988 Brougham (307) carb issue
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5.0 and 5.7 Discussion, 1988 Brougham (307) carb issue in Cadillac Engine Technical Discussion; I picked up the car from an auction house about a few months ago. Everything seemed OK except that the ...
  1. #1
    XL2007 is offline Cadillac Owners Member
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    1988 Brougham (307) carb issue

    I picked up the car from an auction house about a few months ago. Everything seemed OK except that the transmission took (and still takes) its sweet time going into reverse and drive and the lack of a radio I was pretty shocked to see how much of a dead weight the 307 was -- it made my Town Car's 150HP 5.0 feel peppy in comparison. Getting it from a standstill to 40mph took patience and bravery. Horrid gas mileage -- about 8 to 12mpg overall. Initially, I thought my problems were transmission-related.

    Shortly after bringing it home, I took a look at the spark plugs and found them burnt and covered with soot. I replaced them with a new set, had the oil changed and added a can of Restore for good measure. The 307 felt a bit peppier, although it still felt like a slug on molasses.

    The only problem left was starting it up in the morning. The car would stutter, stumble and basically sputter out if I didn't keep giving it the gas. After about a minute, it would run fine and for the rest of the day, it would start right up just like an EFI-equipped engine -- no need to touch the pedal at all. I'm pretty sure it's running rich and you could smell gas coming from the carb, as though it was just dumping too much fuel. Probably the reason for the poor gas mileage.

    Today, I took as best of a look as I could at the carb itself. The choak wouldn't close all the way and as of this moment still lays gapping open. I think it's some sort of linkage problem. When the engine runs, I could hear a large hissing sound as though a vacuum hose was loose or off. I ran out of daylight, so I'll have to go back out in the morning for a good look.

    I plan to change the O2 sensor and the catalytic converter in the next month or so, as well as possibly invest in some new spark-plug wiring. My main question is this: do I have to get carb rebuilt? Or is this a problem that could be taken care of by myself? I feel a bit blind dealing with the QJet and I'm pouring over as many carb-related threads as I can.

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  3. #2
    Johnny Bravo is offline Cadillac Owners Fanatic
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    Re: 1988 Brougham (307) carb issue

    You may need a carb rebuild, however I'd try replacing the front primary choke pull off first and see it that improves the cold start up problems at least.The choke pull off is that small vacuum canister at the front right corner of the carb.

    The choke should be open once the engine is warm, so thats normal. Why don't you check it before a cold start, preferably after sitting overnight. With the engine off, open the throttle by hand and the choke should snap shut. It should stay mostly closed for the first few minutes of warm up as well. Check for any obvious vacuum leaks while you're under there.

    Here is a link for a rebuilt carb if all else fails:

    :http://cgi.ebay.com/ebaymotors/ws/eB...m=200051588871

    The lack of power is simply the nature of the beast with 1985 and later small port "7A" head 307's, not much can be done in that department short of a bigger engine. However, gas mileage has lots of room for improvement.

  4. #3
    Terrifying Toronado is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Sounds like you have a choke problem for sure along with others. I have a '85 Olds Delta 88 with a 307, it runs good (certainly no screemer) but not like for instance a fuel injected 5.0 Town Car. This Olds of mine does get 20 + mpg though. I've been rebuilding QuadraJets for 30 years and know how to make them run, they are great carbs. I suggest you find a older mechanic that has been around since all cars had carbs and have him go through your Qjet.

    Mike

    '93 Eldorado 4.9
    '66 Toronado 7.0

  5. #4
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    I just got back from driving the car around on an errand run. To answer Johnny Bravo's post, I did pull the throttle prior to a cold start and the choke snapped shut.

    The hissing sound was getting on my last nerves, so upon my return from errands, I opened the hood and exposed the Qjet in all it's gold-plated glory. Guess what I found?

    Fuel leaking from what appeared to be a large line in the very front of the carb. I'm not sure whether to call it a vacuum line (although it sure sounded like one), but all I know is that it seems to be either broken, loose or just fitted the wrong way. I do have pics from a camera phone, but I'll take some time to post them here.

    If I have time this evening, I'll go back out and see about tightening it up, if I can.

  6. #5
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Well, it's been a few months and I finally got around to doing a few things to the car, although I think it's taken a turn for the worse.

    I'll explain in bullet form.

    * Shortly after posting last time, I took a wrench to one of the main fuel lines leading to the carb and gave it a good tightening up. As by magic, my cold-start problems and the issue of fuel leakage virtually disappeared. I was a happy man, at least for a month or two.

    * The electronic QJet was still giving crappy mileage (8-10mpg city) and it still felt tremendously winded, so I decided to replace the carb. Took it to a mechanic who suggested switching over to a non-electric (hot-air) QJet. Bought a remanufactured QJet for $200 and sent it back to the mechanic for replacement. While that was going on, I also had the cat hacked off and a straight pipe put in it's place.

    * Mechanic put the carb in, yanked off vacuum hose after vacuum hose (uh-oh), set the fuel mixture, timing, cranked it up........

    It sounded good. At idle.

    Took it for a test drive.

    Problem?

    Well, the engine now stalls out at low idle in Reverse and Drive and if you try to give it 3/4 gas, the engine bogs down and makes a clattering "diesel" noise. The mechanic yanked off nearly every vacuum hose leading to the carb and ended up with plenty of leftovers. Now I'm trying to figure out just where the hell what hose goes to where. Can't understand the diagram for the thing -- what I need is an actual real-life PICTURE of what goes where and what leads to what. Personally, I think 85% of this crap is due to yanked and crossed up hose connections.

    Thought about the distributor and whether or not I should replace it, along with the O2 sensor. But not until I untangle this entire mess with the carb and everything.

    * Bought a set of spark plug wires and installed them just to see if that would alleviate the problem. Didn't help much. Rechecked the spark plugs - no problem there.

    I'm at a loss. Just read the EFE thread and I'm still lost. Can't take it to someone who actually knows what he's doing for another few weeks and I'd rather do this myself. Can anyone help?

  7. #6
    Gwokable is offline Cadillac Owners Fanatic
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    Re: 1988 Brougham (307) carb issue

    First off, pulling the cat is a bad idea unless it's leaking. Hello backfire city.

    The brougham has 6-8 vacuum systems. These systems do everything from making sure the fuel tank doesn't burst to adjusting the idle lever when the car is in drive or reverse (hence the problem with the car sputtering out when idling). Any mechanic who removes them is, in a word, a ****ing moron.

    Just about every brougham has an E4ME quadrajet carb if memory serves. That's the one you need to have on there. From there, you can begin rebuilding the vacuum systems. The 88 has:

    Early Fuel Evaporation system (EFE).

    Thermostatic Air Cleaner system (THERMAC).

    Positive Crankcase Ventilation (PCV)

    Air Injection Reaction (AIR) system with catalytic converter.

    Anti Dieseling Solenoid Circut

    EVaporative Emissions System (EVAP) ystem with MAP circut

    Cruise Control Circut

    Brake Manifold Vacuum circuit.

    The last two are undocumented unless you have a dealer service manual. The rest, save for the PCV, are on the vacuum circuit diagram. PCV is widely used and easily identified. Search and learn then apply.

  8. #7
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Well, I'm in the process of attempting a rebuild of the vacuum system, relying on the diagrams back in the EFE thread. My only problem is finding the Anti Dieseling Solenoid Circut and putting it all back together. Having to swap back to an electric QJet is a bit aggravating, although I now know how to replace a carb and tune it to a degree. I was looking for a solution that wouldn't have me go through all of that, since I'm not in the best of financial positions at the moment.

    As for the cat, it was literally stopped up with crud upon examination. I'm thinking about doing some sort of dual-exhaust set up on it someday -- I'll probably revisit the cat issue then.

  9. #8
    bennyJ is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    I have an '88 Brougham that recently suffered similar issues to those you described. couple of things that I found in my case:

    fuel filter was shot! right on the front of the carb and I didn't think to check it during a regular tune-up, waited until it was so bad I could only make it up hill in reverse (true story, blockage would starve the engine when it was tilted uphill!) new one of them for around three bucks helped a lot!

    Hissing sound coming from near the front of the Carb was due to a crack in the pcv hose right were it connects to the base of the carb.

    I also relieved the tension a bit on the secondary air valve spring and "adjusted" the secondary valve to open all the way when needed. this is done by bending the stop located on the passenger side of the carb (near the back, right by the secondary valve) towards the front of the car. Just bend the stop tab untill the secondaries will pen all the way to vertical. this is the same engine as the olds 442 and has the same carb, it's just tuned differently at the factory and has a few different components internally (cams, heads, etc) but the secondaries are so limited when stock that you only get about half to a third of the air through them as possible. I found that this five minute job woke the old girl up noticeably... still no dragster but it certainly helps. Don't think it will do much good unless the rest of the carb is in good working order, and you have no other air flow restrictions (dirty filter etc...) but thought I'd let you know anyhow.

  10. #9
    Johnny Bravo is offline Cadillac Owners Fanatic
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    Re: 1988 Brougham (307) carb issue

    Quote Originally Posted by XL2007 View Post
    Well, it's been a few months and I finally got around to doing a few things to the car, although I think it's taken a turn for the worse.

    * The electronic QJet was still giving crappy mileage (8-10mpg city) and it still felt tremendously winded, so I decided to replace the carb. Took it to a mechanic who suggested switching over to a non-electric (hot-air) QJet. Bought a remanufactured QJet for $200 and sent it back to the mechanic for replacement..

    * Mechanic put the carb in, yanked off vacuum hose after vacuum hose (uh-oh), ..
    I hope you don't mean that jackass installed an non-CCC controlled carb.
    Most of these idiots haven't worked on a carburated vehicle in ten years, if ever.

    The CCC Q-jet and distributor function together. If you replace the carb without replacing the distributor with a non-ECM version as well, it will have no timing advance, run like shit and be way down on power, (thats the bogging no doubt).
    Furthermore, you'll also have to rig up something to get the transmission overdrive to work as well.
    Wholesale trashing of the vacuum lines and sensors isn't going to help matters either. Some can be safely deleted, others no.

    You should have followed my advice and bought a rebuilt electronic Q-jet in the first place.
    Now it's going to cost you even more time and money undoing this mess.

    I'd suggest you post on http://oldspower.com for Olds 307 engine related issues.

  11. #10
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    If you replace the carb without replacing the distributor with a non-ECM version as well, it will have no timing advance, run like shit and be way down on power, (thats the bogging no doubt).
    And that answers the bogging.

    Now it's going to cost you even more time and money undoing this mess.
    At least I know now how to replace my own carb -- it'll take time, but at least that won't cost me anything.

    Instead of charging on and getting a non-ECM distributor, I'll beat a hasty retreat and get another electric QJet. And put the non-ECM on eBay.

    In the meantime, I've got most of the vacuum lines back to where they should be. The big issue is that there are two places on the carb that don't match where the lines should go. I'm sure that once I get my hands on the proper QJet that it'll cease to be a problem.

    Other things on the to-do list: fuel & transmission filters. And a tranny flush.

  12. #11
    Gwokable is offline Cadillac Owners Fanatic
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    Re: 1988 Brougham (307) carb issue

    For the most part, if you know what each component of the engine does and how it's supposed to operate, you can wire the emissions system damn near any way you want. All the vacuum lines at the car, especially at the base of the carb, provide negative pressure; the line size just determines the amount.

  13. #12
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Well, it's been a while since I last checked on this place. I ended up getting another car while the Brougham was still down (and I dare not utter the brand name ). But all wasn't lost. Far from it.

    * I found another proper electric QJet from another 307 motor at one of the local junkyards. Took it home for the grand sum of $50, cleaned it up a bit, bolted it on, only to have the hardest time trying to keep it at idle. Or getting it to actually crank up in some cases.

    * I took the car and carb to another shop whose owners actually knew what they were doing. As it turned out, the carb was in need of a rebuild (figures) and they also fixed the vacuum hose issue to where the car was finally drivable. It took another $230 in parts and labor, but I could finally take it home under it's own steam.

    Today, it's in the driveway serving as the main ride while the other car whose brand I can't mention is at the same shop getting it's starter replaced (it's under the intake and involves hours of work -- 100 degree temps kinda ruled fixing it myself out). It picks up and goes as well as a 307 in it's condition and age can. The clogged catalytic converter was really taking away HP, but it's deletion introduced the problem of backfiring, which has subsided a bit but it's still present. Gas mileage overall stands at about 11mpg in the city. Highway mileage is still unknown -- it's never been on any serious highway trips.

    The problems I'm now dealing with are largely cosmetic, with the exception of the climate control system. Somehow, messing with the vacuum and the carb managed to knock the climate control fan out of commission. In other words, it won't blow air out of the vents. The headliner's done for and one of the rear bumper moldings finally gave up the ghost. Right now, I'm torn between keeping it and eventually throwing a more worthy engine/transmission into it or selling it off for a decent amount. I'll figure it out within the coming weeks.

  14. #13
    joe_padavano is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Quote Originally Posted by XL2007 View Post
    The problems I'm now dealing with are largely cosmetic, with the exception of the climate control system. Somehow, messing with the vacuum and the carb managed to knock the climate control fan out of commission. In other words, it won't blow air out of the vents.
    The fan is electric and shouldn't be effected by anything having to do with engine vacuum. You should be able to hear the fan operating if you turn on the HVAC. On the other hand, the flapper doors inside the air distribution box under the dash ARE vacuum operated and a loose or misconnected vacuum line will certainly prevent them from working properly. The default (no vacuum) condtion is air out the defroster and out the floor vent under all control conditions. If that's what you have, then you have not connected the vacuum lines properly.

  15. #14
    XL2007 is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Quote Originally Posted by joe_padavano View Post
    The fan is electric and shouldn't be effected by anything having to do with engine vacuum. You should be able to hear the fan operating if you turn on the HVAC. On the other hand, the flapper doors inside the air distribution box under the dash ARE vacuum operated and a loose or misconnected vacuum line will certainly prevent them from working properly. The default (no vacuum) condtion is air out the defroster and out the floor vent under all control conditions. If that's what you have, then you have not connected the vacuum lines properly.
    The flapper doors are engaging when I select between the floor and defrost vents, but the fan is not blowing anything at all. Could it be something that has to do with the fuses or a relay of some sort?

  16. #15
    joe_padavano is offline Cadillac Owners Member
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    Re: 1988 Brougham (307) carb issue

    Quote Originally Posted by XL2007 View Post
    The flapper doors are engaging when I select between the floor and defrost vents, but the fan is not blowing anything at all. Could it be something that has to do with the fuses or a relay of some sort?
    The fan motor is very easy to test. There is a power wire with a rubber cover on the connector and a ground strap or wire. Be sure the ground strap is in place and making contact. Now pull the power wire off and connect a +12V feed directly from the batter positive terminal to the motor terminal. If the motor works, the problem is in the control wiring. If the motor doesn't turn, replace the motor.

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