Results 1 to 17 of 17

Thread: Backfire plus flame out the carb Help!!!!!!!!!!!!!!

  1. #1
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default Backfire plus flame out the carb Help!!!!!!!!!!!!!!

    I have a 258 eith the one barrel carter and it must be out a tune, because it backfires under aceleration and flames shoot out the carb. It runs fine at idle after it starts, but if I try to acelerate a little it bogs and then something pops or releases and a flame comes out the carb and it dies. Does anyone know what it is ,I need help the choke is messed up it stays open and i know it needs to close to start in cold weather could this be whats causing the flame. This is a total guess but could the choke get stuck while reving causing a great amount of gas to build up and then the choke flys open and the mixture is way to rich causing it to back fire and shoot a flame. I just want to figure this out.


    -thanks Derek

  2. #2
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    Well it could be a timing problem. Where the spark plug is firing to early. I would check the timing and see if the vacuum advance is working correctly. The vacuum advance will retard the timing under load such as acceration. I suspect it will be OK but you should check it anyway. Your timing chain could of slipped a tooth.

    Now if your spark plug wires are cracked or you have an old carbon tracked distributor cap, you could be getting cross firing from another cylinder. What happens is one cylinder fires and the spark crosses over to an ajacent cylinder and fires the spark plug in that cylinder. If it happens to be during the intake stroke when the intake valve is open your going to get a backfire out the carb that way.

    Now you could have a cracked or worn valve seat or valve that is allowing a little flame to shoot back out of the intake port setting off any fuel/air mixture in the manifold.

    To lean of mixtures seem to fire off quicker than too rich so having the choke open when the motor is cold might be real lean allowing it to fire off. Now if the accelerator pump in the YF carb isn't working, that can also cause to lean of condition and cause it to backfire. I'm not realy sure of what is happening that a lean mixture causes it to back fire through the carb but I've seen it enough. Maybe the burning in the cylinder isn't completely out out the cylinder when the intake opens again and ignights the mixture as it comes in. That would just be a guess.

    Are you saying your choke closes while you are reving the engine or just guessing? I have seen a lot of strange way a choke can stick open but not to many that causes it to pull shut once it opens. The linkage is set so that it will pull the choke open under WOT.

    I also have a 1 bbl and realy love it once all the little nuisances are taken care of. I also am running a manual choke on mine. I almost forgot it's there since I don't use it in the summer.

  3. #3
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    my distributor cap is very loose could this be the problem. My choke I know doesn't work right so i'll just get a manual choke. My timing should be ok I really don't understand how to even check the timing. What is the vacum advance can I bypass it. It sounds conplicated. What do I look for to see if it's cross firing.


    -thanks for the help so far Derek

  4. #4
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    Don't bypass your vacuum advance, your jeep will run worse than ever. It's just a hose running from your carb to the distributor. You should have one on there. If you don't that can be a problem also.

    Do you have the distributor with clips ?? Then it is a prestolite POS. I would recomend an upgrade. But since it is loose, Take the cap off and see if there are any black lines inside the cap. Run your finger on the inside and see if anything comes off. It should be clean as a whisle or even cleaner.

    Nope a loose cap is bad. See if you can tighten it up. If you have clips like mine did, you might try a large wire clamp but I replaced mine as soon as I could because the clips were rusted.

  5. #5
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    ok I just put the manual choke on tonight. The bracket that came with it I didn't use because it wouldn't bolt up anywhere so I just used some long plastic ties to secure the cable. Works ok for now. Then I took off the dis cap and got a new borg warner one the guy said copper was better then aluminum for the points inside, but it won't stay tight so I'm stuck. I also need to know where the plug wires go. I don't know the firing order. I just replaced the dis with a new one my old died on me twice it was because of a plastic peice inside that broke two times. The new one they said would not do this anymore what are the other bad things about this dis. Right now I wish I had a bolt on dis cap lol. Is there only one way the cap can fit,because if not then how tell if it's fitting right?

    Can a loose dis cap itself cause a backfire if it's too lose??

  6. #6
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    Well a loose cap will let water and stuff inside coating the surface that will make it misfire.

    but you said you replaced the cap and you weren't sure were the wires go. Having 2 wires in the wrong place will certanly make the jeep backfire because the spark may be firing when the intake opens up.

    Do you have a Haynes manual or a Chiltons manual? These will help you to determine the firing order.

    The spark plugs are numbered 1 to 6 with 1 being on the front of the engine. The firing Order is 1-5-3-6-2-4.

    Now as a rough check, find the spark plug wire going to the #1 spark plug on the front of the engine. Going CLOCKWISE looking down at the distributor the next plug wire should go to the #5 plug and the next spark plug wire should go to the #3 plug and so on.

    The next rough check would be to make sure that the static timing is correct. Look for the timing marks on the harmonic balancer and position the pointer to point to 0* TDC on the balancer. Now you have a 50% chance that your at the right position. But lets do a rough test right now.
    The rotor inside the cap should be pointing at the #1 contact in the distributor but you will have to take the cap off to determin this. It will be pointing at either the #1 contact or the #6 contact. If it's pointing at #'s 5,3,4,2 you have the wire offset on the cap. Usually the #1 spark plug wire goes just past the clip holding the cap down clockwise.

    This picture shows what I'm talking about although it has a TFI conversion. You can see the clip and the Spark plug wire to the left is the #1 spark plug wire. The one to the left of that is #5


    Thanks NJCJ7

    Now we have to make sure that it is firing when the valves are close. I think your pretty close because you say it runs but back fires a lot. If it was wrong then it would backfire all the time.

    To do this you will have to remove the spark plug and pout a cork in the spark plug hole or hold your thumb over the hole and make sure there is pressure building up as you turn the engine over BY HAND. If the cork pops off or you feel pressure then you are on the compression stroke and you are fine.

    After you have verified this, then you should check the timing. The best way is to yuse a timing light but there are various other ways. You could use a vacuum guage also.

  7. #7
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    Befor I start thanks so much for helping me. When my old dis was on the wires were in the correct spot. When I took it off I forgot to mark them. I have not tryed to start it with the new ones on. That would be very dumb. It backfired when they were in the correct spot. I just don't know which one is #1 on the cap. I haVE NOTICED on the prestolite a notch so the cap only fits one way I just need to know where the #1 spark plug goes then I can figure out the rest. Oh by the way whats so bad about the prestolite is it the plastic peice inside? One more thing I have a reprint of the factory service manual if it's in there where is it at. Also what is the black rubber thing for on the top on the dis cap.


    -thanks so much for helping me out would you like to see a pic of what my jeep use to look like before my friend rolled it. I say this because I'm still mad at him for that. Derek

  8. #8
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    I think that black thing is a vent for the cap to release any buildup of pressure. I'll have to pull mine out again one day.

    As you know the caps dont fit very well and you can't do an upgrade like you can with a DuraSpark system used in 78 and later CJ's. I ran with a plastic bag over the distributor in the winter because the slush and snow would cause it to backfire and miss a lot. After I switched distributers my jeep ran so much better and after the TFI upgrade I couldn't be happier unles I had a MSD 6a.

    When you put the distributor did you get the rotor in the same position as the old one. ??

    Usually the #1 Sparkplug wire goes in the position you see in the picture. Just to the left of the clip closest to the firewall. The vacuum advance should point to the front of the jeep but this is allways variable depending on the skill of putting in a new distributor.

    Save yourself a lot of greif and buy a Haynes Manual. I like them the best next to the Factory service Manual.

    You bet we like to see picture on this BB. Both before and after the roll over. How did he flip it??

  9. #9
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    The jeep looks a lot better than th day it rolled. I have no pics I can can of the day he rolled it. He rolled it around a gravel turn. He took it to tight and the road had a ditch in the inside of the turn. Any vihicle would have rolled in the spot. It makes me mad because everyone says jeeps are so bad for rollovers for one they are the only ones who put factory roll bars which I'm sure saved my life. I think jeeps are one of the safest not the most deadly. Thoses samuris are way lighter and higher up with smaller wheels than any 70's jeep.

    Anyway how do I post pics I have them just don't know how to post them.

    thanks DErek

    One more thing I'm going to try and do the tfi upgrade even thou I just bought a new cap form borg warners 15.00. I just feel like its going to be really hard to install the dis in the engine. Which TFI set up wpuld work best in my 1977. Also how do you time with a light or timing light. I put the plugs wires back on after I put the dis cap on and know it won't even fire up As I crank all I hear is a puff sound out the tail pipe So i think the wires are on wrong. This just isn't my week I had planned to go to the MIOBI club in Iowa this friday, because I really want to join a offroading club but that didn't work because of the backfire problem.

    Jeeps you love em or Ya Hate em Thanks Derek

  10. #10
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    Also you said the chilton is better than the Factory service Manual because I have the Factory one it's like 400-800 pages long. Or did you say the chiltons is next best to the Factory one.

  11. #11
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    The factory Service manual is the best. I like the Haynes Manual next best then the Chiltons.

    You can't do a TFI upgrade on a prestolite distributor. There is no adapter for that. You have 2 choises.

    Put in a Duraspark distributer with a Elctronic Control module and all the extra wiring that goes along with it OR just do a GM HEI upgrade and connect 1 wire.

    With Durasprk you can hook up a MSD 6a ignition module and have the best of all worled. I don't know if you modify a GM HEI in that way . maybe someone here can help us on that.

    The TFI gives just a tiny more spark than a GM HEI but the GM is easier to install.

  12. #12
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    Could I run the dura spark with just stock coil and wires until I get the rest. I just want a dis I can intsall and upgrade to the TFI when I'm ready. I'm talking about the dis thats found in 1978- up cj-5's. Is there a dis I can drop in and use my coil and wires and ignition box? and then later drop the adaptor and other rotor and new wires and plugs and coil. I'm saying this because I was told you could use the TFI with the stock ignition box as long as you kept under 4000 which I don anyway? If Im mixed up at all just strighten me out

    thanks Derek

  13. #13
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    Yes you could Run a DuraSpark setup from a 78 of later CJ. The distributor will drop right in but you should try to get the ignition wiring harness off the jeep if you can. This will make it easier to connect.

    Here is what it loks like and it came out of an 79 PACER but I think any AMC product of that era would work:

    LINK

    Try to get the other connector to the ICM also. It will make it easier to connect wires later.


    How are you at wiring things up? I ask because the GM HEI is easier if you have any problems with wiring. You can even use the drive gear off your Prestolite distributor to put on the GM HEI distriutor.


    TFI Upgrade GM HEI Upgrade

  14. #14
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Icon5a

    Well I got it started. I'm so happy. I'm stil having probs. By the way the #1 was between the vaccum advance. I tried the cork thing but it wouldn't fly out it justed hissed alot. So I did it the jeep way...I guessed and was right. Anyway under accel it bogs very bad and if I continue to give it gas it will die. So I have to feather the cutch wich is pobbley bad for it. So what do I check next. I think my timing my be way off. Also my fast idle is at 2000 after I installed the manual choke. I'm going to try and do the HEI hope that helps. I keep hearing somthing pop before it dies. It will bog then pop and then die.

    thanks so much for the help so far I just to get it running alot better before I drive it on the road.

    Also do you know how I would post pics thanks again Derek

  15. #15
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    Anyone??

  16. #16
    Forum Leader John Strenk's Avatar
    Join Date
    Feb 2001
    Location
    Kent, Oh
    Posts
    9,772

    Default

    Well I think your going to have to get a timing light for the rest of the adjustment and for posting images you just have to put the the internet addres of where your hosting your pictures between these what-u-might-call-its [ img] [/img ]

    Like this: [img] http://www.LGC/Milkyway/sol/earth/us.../mypicture.jpg [/img] only don't put spaces in.

  17. #17
    Registered
    Join Date
    Dec 2001
    Location
    Newton,Iowa,U. S. A.
    Posts
    242

    Default

    Sorry it's been a lon time since I've posted. I now have 200 to throw at a stronger ignition system. Should I just buy a new GM dis. and the other parts because it's winter and I don't think I can find a dis. in the junkyard that will work. If I do get a new one were is the best place to get it and what year model should I ask for. You also said I could use the old dis. gear. Lastly can I do away with the stock ignition box or is there an even better alt. route. I need to get this running reliable (funny I said jeep and reliable in the same sentence) because I sold my other car (1993 Talon AWD Turbo) to put some of the money in my jeep.

    If anyone has a dis that will work for me tell me a price. At this point I'm leaning towards the HEI. thanks Derek

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Jeep Parts | Jeep Accessories | Trektop NX | Jeep Seat Covers | Jeep Wrangler | Jeep Wrangler Parts | Jeep Wrangler Accessories | Bestop | Jeep Tires | Jeep Stuff | Jeep Wrangler Tires | Jeep Wheels