Screwy acting engine

Discussion in 'Mechanic and Repair' started by Envy Lawn Service, Mar 27, 2003.

  1. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    OK here is the deal. It started off like just barely turning the engine, more like just bumping it around very little. So I assumed "yep the battery is dead." So I installed a battery out of another mower I knew was good.

    No dice!

    So I traced the wires, everything looked good. So I said "yep, it's the solenoid." So I threw the battery on the charger and went for the part. Came home, put it on and replaced the battery.

    Bam! it turned over and finally fired!

    Anyways, it spun allot before it finally cranked. It spit a mist of gas out the pipe so I figured it was a bit flooded. Everything went well. It ran and cranked all yesterday. But when I went to crank it today.

    No dice! Same deal as before!

    So I said "yep must need a new battery, probably didn't hold the charge. So I went and picked one up. I brought it home and installed it.

    No dice!

    As I said it was acting sorta like it was locked up or in a bind. So then I decided to remove the shroud to check and see if something could be lodged in there. Nothing was in there and everything was still clean as I remove it regularly and clean everything.

    So I was thinking hummm :confused:
    I went ahead and tried to start it again and it turned over fast. It did same as before, spun allot before finally cranking. Then I shut it off, swapped back to the old battery, double checked the starter cable, removed inspected and put it back.

    Turned the key and it cranked just fine.

    So now I am seriously confused as to what may be causing this. No doubt I have wasted money on a new battery and solenoid. Plus I have a good bit of time invested and still have a situation I don't trust.

  2. ducky1

    ducky1 LawnSite Senior Member
    Messages: 252

    sounds like the carb may be leaking gas into the cly. and locking up the cly. When it does not want to crank pull out a spark plug and crank over and see if gas comes out of the spark plug hole. Be sure and don't let the spark plug wire jump spark and start a fire. Thats not cool. You didn't mention what breed of engine you have. If the cly. has fuel in it you may need to check the oil and make sure it is not thinned down with gas. good luck
  3. SWD

    SWD LawnSite Senior Member
    Messages: 988

    Depends on what kind of motor you are referring to. Kohlers with the automatic compression relief will sometimes act like that.
    Please provide info on the machine, motor, hours- etc
  4. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    The engine is a Briggs Twin II I/C opposed twin with tons of hours. This engine is not just an I/C Briggs. It does carry a full 2 year commercial warrenty and I believe it is still under warrenty.

    I would go ahead and take it in but all the shops are so backed up right now. So I am looking for a little quicker fix.

    It cranked and ran this morning. But there was a heavy mist of gas coming out of the pipe. I even noticed some leaking from the left header at the cylinder. My guess is that the idea that gas is leaking from the carb is right.

    My question is, would this cause that lock up effect? That's really what it acts like. So much pressure in the cylinders that it doesn't want to turn over. Then when it does, it blows acts flooded and blows gas out.

    I pulled the plugs after getting it cranked. They are real black. As far as the oil, I haven't checked it to see if gas has gotten into it. But I will.

    I believe this is right on though because the only other thought I've even had is maybe the starter is weakened, maybe the Bendix is not operating properly or maybe that spring between the starter and gear that engages the flywheel may be weak.

    Anyways, is this something I could adjust out at the carb?

    Would the block breather valve be involved in this at all?

    Also I will look into the compression relief idea and see what I find.

  5. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    Well, I went ahead to an old repair guy today to pick up a set of new plugs for it. While I was at it I went ahead and threw the engine shroud in the truck so the guy could have a look at the model.

    My dad and I have done lots of repair buisiness with him over the years and he is very good to me in helping out with anything he feels I can fix. His advice was...

    #1-Check to make sure the gas cap vent is good
    #2-Replace the fuel filter
    #3-Replace fuel lines
    #4-If none of that works get a carb kit

    I went ahead and picked up a fuel filter to install and passed on the fuel lines since they appear to be in real good shape outside. But I guess that really has no bearing on the inside of the lines. I'll check inside the carb for any little hose particles. If I find some I'll replace them.

    I had already checked the oil this morning. It didn't appear over full or thinned by gas. But it did have a sent of gas. I'll be changing it reguardless though to avoid any potential problems.

    The repair guy said he was surprised the oil wasn't full of gas with that amount being in the cylinder. He said I must take good care of it and keep it serviced regularly. Otherwise there would surely be significant wear to allow a lot of gas to easily pass by into the oil.

    I installed the plugs and fuel filter this afternoon. I'll change the oil in the morning and see how it goes.

    Last questions....
    The engine manual points out a screw for the "non-adjustable air fuel mixture jet." What's with it being non-adjustable? Might it not be useful to reduce the fuel and increase the air mixture in a situation like this?
  6. Hud

    Hud LawnSite Member
    Messages: 63

    I think you're getting some bad advice from your service people. You're getting gas to the carb because it's in the cylinder so we know: the gas cap works, the fuel filter isn't blocked, and the fuel lines aren't stopped up.

    "...He said I must take good care of it and keep it serviced regularly. Otherwise there would surely be significant wear to allow a lot of gas to easily pass by into the oil..." I think this is called a "snow job." What service is done to keep gas from flowing past the rings? If you have massive amounts of gas in the cylinder, you have gas in the oil. If you can smell the scent of gas, there's gas in it.

    The air/fuel adjustment screw has nothing to do with it. If you have a carb, you have a float with a needle & seat. Close/turn off the fuel shut off valve (you should do this whenever the engine is not running). Carefully drop the float bowl, and check for debris in the float which might be causing the needle to not close/seat properly on the seat. Check to see if the float has a hole in it (shake it to see if it has gas in it) which if it does will cause it to hold the needle open on the seat letting gas flow unrestricted into the carb then into the cylinder. If you hear something sloshing around in the float, replace it. Make sure the float level is adjusted correctly. And at the same time, if it's an old engine, the needle and/or seat may be letting gas pass through so the needle and/or seat may be worn out.

    And if you don't understand any of this, have a qualified person, other than the one you've been dealing with, fix it for you.

    Hope this helps. Let us know how you do with it.
  7. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087


    Humm.... You would have to tell me that after I put everything back together. :D

    Ah well, not too much to tear back into the carb though. The strange part about all of this is that since replacing the fuel filter I have had zero problems. But that's not to say something isn't still wrong or that there wasn't a piece of debris at the float that has passed on now.

    I was sort of under the impression that he was thinking there was debris in there from fuel lines breaking down or otherwise. Also, I don't think he was saying the fuel filter was in fact clogged, but more likely allowing an unrestricted gravity feed of fuel into the carb.

    I don't know though. Maybe he was giving advise to further enhance the flow of fuel so I'd be forced to bring it in. Either way, I have another service man I trust. But as I stated he is very backed up with spring repairs right now.

    I will take it back apart myself tomorrow to see what I find. I really want to be sure I can count on it before leaving with it on Monday morning.

    Oh, and about the oil. I never intended to take a chance on rather or not it was contaminated with gas. I just went with the assumption that is was. I think all the guy was getting at is that he would assume since there was that volume of gas in the cylinder that it would stand to reason that an amount of gas large enough to significantly raise the oil level on the dipstick would be present.
  8. Hud

    Hud LawnSite Member
    Messages: 63

    ELS, I wasn't trying to ruin your day.:)

    "...Also, I don't think he was saying the fuel filter was in fact clogged, but more likely allowing an unrestricted gravity feed of fuel into the carb..." Actually, in these engines, I believe this is exactly how fuel filters are supposed to work. A fuel filter that doesn't allow unrestricted flow of fuel to the carb is clogged, and needs replacing.

    Anyway, before you take the float bowl off the carb, check to see if the float bowl has a drain plug/screw on the bottom for draining the water/gunk/yuck out of the float bowl. If it does, pull the plug, and see what you get. Remember, a tiny speck of dirt between the needle and seat, a worn needle, a leaky float, or an improperly adjusted float won't allow the float/needle/seat to stop the flow of fuel. Then if you leave the fuel valve turned on, gravity will do the rest. This is how we used to blow up the engines on our old Triumph motorcycles (which were new at the time we had them) when we'd forget to turn off the fuel valve.

    I hope this is your problem because it's simple to fix. I might be wrong, I often am, but the rest of the stuff they told you, including the above line about the fuel filter, just doesn't make much sense to me.

    Good luck with your wrenching. Give us a report when you've fixed it.
  9. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087


    Thanks for the info! I'll put it to use tomorrow if this rain that has started lets up.
    I haven't paid real close attention to the carb yet really. Best I can remember there is maybe one srew that could be a drain. Otherwise, there are only 3 screws that hold the cover on where the fuel enters from the line. I checked the manual to see if there was any reference to the drain in the "STORAGE" section. Their was none.

  10. Hud

    Hud LawnSite Member
    Messages: 63

    You know ELS, if the unit is running well now, you might have cleared any debris blocking the needle & seat when running the engine. You might want to think about just leaving it alone, but making very sure to close the fuel valve every time you turn the engine off.

    But if you do want to drop the float bowl to check it out, remove the screws, and keep the float bowl/needle/seat assembly level when you lower it from the carb. When you look at it, you'll understand immediately how it works, and what I'm talking about. And how simple it really is. Good luck!

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