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  1. #1
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    47

    Default LM 318 Wont Start

    Hey guys, First, I should tell you what I replaced then I'll tell you my symptoms.

    1 New Distributors (Pertronix D241800)
    2 New Coils ( Pertronix 45111 ) No external Resistor Required
    3 New Carbs ( Edelbrock 1509 )
    4 New Manual Fuel Pumps (Edelbrock 1720)
    5 New Spark Plugs and Spark Plug Wires
    6 New Fuel Lines and Inline Filters
    7 New Ridged fuel line from pump to carb.
    8 New Engine Wiring harness
    9 New Fuel Tank and yes gas is fresh.
    10 New Marine Gear reduction Starters (My best Purchase so far!)

    So I have two inboard lm318's. The port engine starts fine and has the same parts as the stbd. Keep in mind when you post a reply that my boat is 1200 miles away and I wont get back to it for another month. I'm going to compile a list of things to try next from this thread.

    I can crank and crank the engine and after maybe 20 attempts I get ignition maybe three times. It will only run for 5 to 10 seconds and only with WOT. I thought maybe I had a flooding issue because the spark plugs were wet after every start attempt. Here's the list of things I've tried so we don't get redundant with this thread....

    1 Grounded spark plug verified spark
    2 Verified timing twice. #1 cylinder at TDC compression, (yes I already know where #1 is from the mile long historical thread, LOL)
    3 Removed fuel line from carb verified fuel flow. (next trip I'm bringing a pressure gauge for T/S)
    4 Swapped carbs from working motor, stbd still won't start and port runs fine with stbd carb. Carbs OK! I plan on doing the same thing with my fuel pumps next trip.

    I guess that's basically it because I followed the basic engine T/S tree. Fuel, Ignition and air. I can ad some more history that might help. Bare with me.

    The boat was sitting for three years in a yard. The usual layup was done before winter. So anyway the day before that I was going to put the boat in the water I wanted to make sure I had at least one operating motor. The port wasn't ready yet so I focused on the stbd. I put the new edelbrock 1509 carb on the stbd engine and it started right away, no hesitation. I ran it for about 30 minutes and then I was satisfied that it would be fine. I also plumbed in an electric fuel pump on the stbd tank to suck out any water that might have been in it. The next day I put the boat in the water and tried to start the stbd engine. It ran horribly, tons and tons of black smoke was coming out the exhaust. Too much fuel right? It only would run at WOT. After a few minutes of that crap I shut it down and could never get it started again. I thought maybe from transport I stirred something up in the tank, but here's the strange part. I have fuel selector valves for my motors. I can run the Port engine from either the stbd or port fuel tank. The port engine runs fine from either tanks. So its not the fuel tank. The only other thing I can think of is maybe I have an obstruction in the selector valve for the stbd engine or some kind of blockage downstream of that. But the symptoms show too much fuel not fuel starvation. I'm a little confused as to why it wont run at all. Any suggestions would be much appreciated and I'll take your advice and put it into action next time I'm in Alaska. Thanks

    Russell

  2. #2
    Join Date
    Nov 2005
    Location
    Chi West, IL, USA
    Posts
    757

    Default Re: LM 318 Wont Start

    I'd verify TDC on the compression stroke for #1 cylinder.
    Verify distributor rotor is pointed to #1 with proper rotation direction and proper firing order.
    Compression check cold.
    Check wiring for loose connections and possible shorts.
    Getting oil pressure?
    If you pour a little fuel in the carb with little or no throttle will it fire off right a way?

  3. #3
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    47

    Default Re: LM 318 Wont Start

    Thanks Dave, Yeah I've doubled checked the timing twice. #1 TDC Compression Stroke. Firing order on Stbd engine is 1-2-7-5-6-3-4-8. I aslo get good spark so I dont think its ignition, but I've been wrong before. Compression check cold showed all cylinders are between 110-120 psi. I also double checked my wiring, its brand new but it's a very simple harness. White wire-Coolant Temp, Black Wire-Oil Pressure, Grey Wire-Negative side Coil to Tach, Blue Wire- Positive side Coil to Ignition SW, Red Wire Starter. I have no ignition module or ballast resistor on this boat so you can eliminate any issues there. The last two items I haven't tried so I'll add those to my list. Thanks for your input!

  4. #4
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,190

    Default Re: LM 318 Wont Start

    You might have fouled plugs from earlier starting attempts. Pull out the easy ones to get to, clean them with carb cleaner, spin her over with them out, install and try again.

    Jeff

  5. #5
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    47

    Default Re: LM 318 Wont Start

    Thanks Jeff I'll add that to the list!

  6. #6
    Join Date
    Dec 2014
    Location
    Ontario Canada
    Posts
    49

    Default Re: LM 318 Wont Start

    Check the gap between the reluctor and the pick up. Make the gap on the problem engine the same as the good running engine.
    Last edited by Toonl; 09-18-2015 at 05:53 PM.

  7. #7

    Default Re: LM 318 Wont Start

    try running a wire from the positive side of the battery to the coil screw not going to the distributor, give the engine a quick shot of ether to save on cranking, try cranking the engine if the engine starts & runs the problem is in your ignition switch. to shut engine back off just remove the wire from the battery. this just bypassed the whole ignition switch

  8. #8
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    47

    Default Re: LM 318 Wont Start

    Latest Update, I started with the three basics, air ( yep its got that ) Fuel ( yep that too ) and Ignition ( check lots of spark ). After a whole day of T/S this motor it came down to pulling the valve covers. Glad I did because the #8 exhaust rocker arm was loose. I pulled that off and found a bent push rod. It still bugged me though cause even with one push rod bent it should have started so I pulled the head. I found metal in 2,4,6 and 8. Pulled the other head and found the same thing in 1,3,5 and 7 cylinders. The boat is in Alaska and I had to leave that day so I haven't figured what happened yet. I know the metal in #8 is from the exhaust valve that crapped itself but the rest are unknowns for now. At least now I can quit scratching my head and save what hair I have left.

  9. #9
    Join Date
    Apr 2016
    Location
    barnegat NJ
    Posts
    2,707

    Default Re: LM 318 Wont Start

    good luck with those engines your perseverance is admirable!!

  10. #10

    Default Re: LM 318 Wont Start

    Very normal for pieces to spread throughout the engine through the manifolds. Hopefully there isn't too much piston damage, but I suspect there is.

  11. #11

    Default Re: LM 318 Wont Start

    Hey guys quick question hopefully. Any ideas why my 1976 Lm318 keeps flooding ? I sat a new carb and also fuel filters on and it keeps flooding.

  12. #12

    Default Re: LM 318 Wont Start

    Quote Originally Posted by CaptTaz View Post
    Hey guys quick question hopefully. Any ideas why my 1976 Lm318 keeps flooding ? I sat a new carb and also fuel filters on and it keeps flooding.
    I had a simillar problem. If your fuel pump has the hose to the carb, make sure the fuel pump is not leaking through the hose going up to the carb.
    the other issue could be a stuck choke.
    Good Luck
    Bob

  13. #13
    Join Date
    Apr 2016
    Location
    barnegat NJ
    Posts
    2,707

    Default Re: LM 318 Wont Start

    Float in carb. hanging up CaptTaz, Do you have spark? Will engine run at all? Some history on your vessel might be helpful, Was a compression test run yet? CaptTaz start a new thread on your own, you will get better responses.
    Last edited by johnnygjr; 04-15-2017 at 07:01 PM.

  14. #14
    Join Date
    Nov 2005
    Location
    Chi West, IL, USA
    Posts
    757

    Default Re: LM 318 Wont Start

    What carb?
    Some Possibles........Did you happen to use Teflon tape on the inlet that may be fouling the needle/seat? Bad needle and or seat. Float set too high. Float hanging or filling with fuel (sinking).
    Way out there.. excessive fuel pressure.

  15. #15

    Default Re: LM 318 Wont Start

    Likewise what carb. Pic of engine with carb installed?

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