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Thread: Stalling

  1. #1
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default "I'm trying to help a frie

    "I'm trying to help a friend with his 4.3L 6 cylinder Cobra. The problem is the engine just "dies" at idle and won't restart. Sometimes it's as sudden as if you turn off the key, other times it looses rpms quickly and then stops. This happens very rarely and without warning. I checked for vapor lock but it appears to be getting plenty of fuel into the carb and intake. There does appear to be good spark going to all the plugs but I'm starting to feel this problem is electrical...Coil, Condenser? The carb was rebuilt last fall and it has been running great until a week or so ago. Fuel and filter are clean, timing is currently 2 BTDC, vacuum is 22 lbs."

  2. #2
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
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    3,727

    Default "disconnect the battery, Follo

    "disconnect the battery, Follow the neg cable to the engine ground remove the ground clean shiny clean the connection and the stud at the motor, and reattach.

    check the slav solenoid, it grounded well, the connections good? Remove and clean the ground, the solenoid is grounded by the base.

    Follow the wires to the starter,clean those connections.

    The main harness plug pull it apart it clean in there? maybe green bad connection? The 2 main fuses held in the spring clips pull apart and inspect the connection for the fuses it green in they corroded?

    The connections at the coil they clean? clean every connection.

    How about the kill switch, if you have one, it popping.

    Try the above post back."

  3. #3
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default I'll clean all the connect

    I'll clean all the connection this evening and let you know the results. This really has me baffled. I ran the engine the other day for about 4 hours and it never stalled but then again it will "die" after only 15 minutes at other times.

    Thanks again...this is a great forum.

  4. #4
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default "Okay, here's the latest.

    "Okay, here's the latest. I cleaned every connection from the battery to all components on the engine. During the sea trial the engine started loosing top rpm (3800 dropped to 3500). Bringing back the throttle to idle speed the engine started sounding like it was running on just a few cylinders....increasing the throttle kept the engine from dying. There was some back-firing thru the carb. It showed all the symptoms of bad fuel but the fuel in the filter was clean. When I reached the dock the engine died completely as before and refused to start. The problem seems to occur after the engine heats up. I'm going to let the boat set tonight and start it in the morning to hear if there is a difference.

    I'm open for suggestion."

  5. #5
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
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    3,727

    Default "Ok you cleaned the filter in

    "Ok you cleaned the filter in the fitting that enters the carb?

    You have a fuel filter in the fuel pump?

    You check the fuel / water separator, and dumped it in a clean clear container and let it sit? what do you see.

    You took off the anti-syphin valve and checked to see if it's clean and not gunked up? The fuel pickup tube have a screen on the bottom it clean?

    the fuel pump giving you between 4-6 psi no less.

    The carb rebuilt when? could be all gunked up.

    when was a full tune up done last?"

  6. #6
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default "The filter going into carb is

    "The filter going into carb is new and clean.

    The canister fuel filter next to the fuel pump is new and clean. This is what I emptied and checked. I let the fuel sit then slowly poured it off. I noticed no dirt or water.

    I removed the anti-siphon valve, cleaned and checked it. I have not removed the pickup tube. I will do that.

    I have not checked the fuel pump pressure, with a gauge. I took the exit fitting off and it shot fuel quite a distance..but I will measure the pressure with a gauge to do it correctly.

    The carb was "professionally" rebuilt last fall and checked again two weeks ago. It was clean.

    The last full tune up was last spring but I'm going to do another just to eliminate the possibility of a cracked cap, bad condenser, etc.

    My friend runs this boat a lot so the fuel doesn't sit but I do have concerns on what is going on inside that original tank.

    I'm also considering running the engine from an external fuel tank to see what happens.

    After I finish my coffee I'm going to try the engine again and see what happens."

  7. #7
    Join Date
    May 2007
    Location
    Kawarthas
    Posts
    3,224

    Default might want to also run a compr

    might want to also run a compression test and during that test you can look for water in any cylinders...
    Factory Manual Best, Seloc 2nd best, Clymer if you're desperate.

  8. #8
    Join Date
    May 2007
    Location
    Kawarthas
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    3,224

    Default throwing a new coil on is neve

    throwing a new coil on is never a bad idea as well
    Factory Manual Best, Seloc 2nd best, Clymer if you're desperate.

  9. #9

    Default "Mine was doing similar things

    "Mine was doing similar things, turned out to be ignition tune up fixed it. I believe it was the condensor, but I changed plugs, points, condensor, cap and rotor and also put a new coil in."

  10. #10
    Join Date
    Mar 2008
    Location
    El Dorado, AR, U.S.
    Posts
    317

    Default Have you checked the centrifug

    Have you checked the centrifugal advance mechanism in the distributor? It could be sticking intermittently.

  11. #11
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
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    Default "chuck is good beat me to it.

    "chuck is good beat me to it.

    Timing chain loose skipped a tooth, or broke off a few teeth?"

  12. #12
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default "Well I've been busy thank

    "Well I've been busy thanks to you guys.

    I checked the pickup tube, measured fuel pump pressure, replaced all ignition parts, rotor, condenser, points, cap, coil, wires, plugs...etc.

    Compression check shows around 180 on all cylinders and no sign of water.

    Since I did those checks and made those changes I've put about 5 hours on the boat and have yet to get the problem to show up ... maybe I got it ... maybe not. If not I'll pull the distributor and have the centrifugal advance looked at plus run the engine from that external tank.

    I returned the boat to my friend to run, I'll keep you guys posted on what happens."

  13. #13
    Join Date
    Jun 2009
    Location
    prince george, British Colombia, Canada
    Posts
    89

    Default "I also have a stalling proble

    "I also have a stalling problem. I have twin 4.3 v6 that like to stall, mostly when shifting.I solved the problem by running a jumper wire from the coil directly to the battery.The only problem with this is you have to pull the jumper off when you wish to shut the engine off, so I put a continuous solenoid activated by the ignition to run power directly from the battery to the coil. It is a considerable distance from the power source to the key than back to the coil and a few loose conections or a little carrosion at each connection can cause a power drop befor it reaches the coil. This solved my problem, I hope it can be of some help to you."

  14. #14
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
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    Default "I don't know about hookin

    "I don't know about hooking another solenoid, i would have just run a wire to the dash with a switch, a simple toggle on off switch. You could put 2 side by side and marked ign. no one will be able to steal the boat cause they won't know what they are for.

    But your problem second poster is a ground problem.

    or the connections are bad, or the main harness for both motors need cleaning, or a combination of all the above."

  15. #15
    Join Date
    Jul 2006
    Location
    Keswick, Ontario, Canada
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    1,847

    Default James....by bypassing the resi

    James....by bypassing the resistor wire with your solution you will burn up your ignition as it's not designed to run with 12v all the time like that.

  16. #16
    Join Date
    Jun 2009
    Location
    prince george, British Colombia, Canada
    Posts
    89

    Default Hi Bob I also have a jet boat

    Hi Bob I also have a jet boat with a 375hp small block GM that had a high RPM flutter. I fixed this by running a direct link to the battery through a solenoid and have had no problems. As both boats have electronic egnitions I think it should be OK.

  17. #17
    Join Date
    Jul 2006
    Location
    Keswick, Ontario, Canada
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    Default "OK James...you neglected that

    "OK James...you neglected that little detail about the electronic ignitions which makes a big difference but still surprised that you need to to go to all the trouble of the solenoid when all you really needed was a clean 12v source, but whatever works!"

  18. #18
    Join Date
    Jun 2009
    Location
    prince george, British Colombia, Canada
    Posts
    89

    Default The boat with the 4.3 v6 engin

    The boat with the 4.3 v6 engines is 26 feet long with the wireing under the floor and when I first got it I had to install a new fuel tank. There are 4 sets of wires down there with conections. I checked them when I was in there and they all appeared to be clean. To get at them I have to tear the interior out and I have no desire to go there again. It was much easier to do my fix.

  19. #19
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default Out of curiosity what should t

    Out of curiosity what should the ballast resistor cut the voltage down to at the coil?

  20. #20
    Join Date
    Jul 2006
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    Keswick, Ontario, Canada
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    1,847

    Default Wilton....probably down to aro

    Wilton....probably down to around 7-9 volts

  21. #21
    Join Date
    Jun 2009
    Location
    Baltimore, Maryland, USA
    Posts
    13

    Default "Well guys, so far so good. Th

    "Well guys, so far so good. The engine has about +20 hours since my last repairs and there has been no stalling. I'm not sure what the exact issue might of been but I'm not complaining."

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