general fuel question

[jdstephwacotx]

Once a motor idles....if you continue to pump the bulb (assuming the bulb and lines are in good working order) should the motor flood and die?<br /><br />I'm trying to think of ways to trouble shoot everything between the tank and the carbs and I have no experience.<br /><br />Other suggestions welcome.<br /><br />Also, when the cover and wrap is off and I can see into the tops of the 2 carbs (inline 4 outboard) should I see fuel spraying into the carbs when I pump the bulb (motor off now)? I definitely should if I rock the throttle between forward and neutral right?

 

[Terry H]

Re: general fuel question

inline 4 huh? Prolly not a j/E problem. What's the problem, someone here can surely let you know how to troubleshoot. No, you shouldn't be able to flood the motor from the primer bulb if the carbs is working properly, and no fuel should spray outside the carbs at any time nomatta what...and last but not least, what motor are you working on, model # and brand...

 

[LubeDude]

Re: general fuel question

Right on Chief!!!

 

[jdstephwacotx]

Re: general fuel question

Not outside the carbs. I meant when I'm looking into the carbs with the motor off. What can I do to see if fuel is spraying into the carbs as it should?<br /><br />76 Merc 85HP <br /><br />What sort of symptoms should I have if I'm getting air in my fuel lines from a bad bulb or connections?<br /><br />It idles fine but quits when I put it in gear.

 

[Bradster941]

Re: general fuel question

No.<br />Pumping the bulb will fill up the bowls of the carbs..<br />Once full, the needle and seat will close and the bulb will get firm.<br />As stated above, pumping the bulb should never result in fuel spraying through the carbs.<br /><br />To answer your last question;<br />If your fuel system is sucking air, your motor will stall.<br /><br />"Also, when the cover and wrap is off and I can see into the tops of the 2 carbs (inline 4 outboard) should I see fuel spraying into the carbs when I pump the bulb (motor off now)? I definitely should if I rock the throttle between forward and neutral right? "<br /><br />Again no. These carbs do not have an accelerator pump like a car carb..<br /><br />Perhaps if you posted what engine and problems you are having, help would be easier to obtain.

 

[WillyBWright]

Re: general fuel question

Actually, I'm afraid I have to disagree with that. The old inline carbs have very wimpy float valves. It's actually not at all hard to overcome them with a decent primer bulb. In fact with the motors that are pretty worn out, that's about the only way you can start them. For every other motor I can think of, you shouldn't be able to overcome the float with the primer bulb.<br /><br />If you have a timing light, you can flash the inside of the carb throat and see a pretty obvious stream of gas shooting out the tube in the lower middle of the carb when the motor is running. You should see the vast majority of it going in towards the motor. Some will also spit back, but the amount should be very small. If it were significant, that would mean a bad reed.<br /><br />The problem you are describing is common with inline Mercs with a lot of hours on them. The reed blocks inside the motor wear and leak between cylinders making any attempt to run them in the water difficult. They can run great on muffs all day long, but as soon as you get some exhaust back pressure, they fall apart. Unfortunately the only cure is an overhaul. But don't assume that that is the problem. It could be a few other things as well. You'll want to repost under the Mercury heading, but I'll bet a moderator will be around to move you anyhow. In fact I'll alert them.

 

[jdstephwacotx]

Re: general fuel question

Don't worry Willy I've already started a more specific thread over there. I like asking my general questions over here. You guys are great.........and quick!<br /><br /><br />I took some things apart just now and I'm beginning to wonder if it is my fuel pump. Would a bad fuel pump allow the motor to idle and even rev with the fast idle lever but die in gear?

 

[Solittle]

Re: general fuel question

Troubleshooting is best done in a methodical step by step manner. Seems you are wondering if it is this or that and posting here and there. Suggest you get a Merc manual and confine your posts to the Merc section. Those folks know Mercs.

 

[JB]

Re: general fuel question

This belongs in Merc Troubles.

 

[zantz]

Re: general fuel question

jdstephwacotx, <br /><br />I have read both of your posts, good luck on keeping up with both of them. Tell me if I have this correct.<br /><br />The motor idles fine, and revs up fine with the fast idle lever, but dies as soon as you put it in gear. Is this correct?<br /><br />If this is the case, I saw in another post, a guy had the same problem. He spent hours checking the whole motor out. It finally turned out to be a short in the shift control box. When he put it in gear a short in the ignition wire killed the motor.<br /><br />There are a lot of experts in here and it seems you have covered the fuel angle, but every now and then you have to stop and think about the problem. If the problem is just as I described, then I'm sure there is a way to disconnect the ignition, start the motor, and put it in gear to see if it dies.

 

[jdstephwacotx]

Re: general fuel question

Yes that is the exact problem.<br /><br />I don't know anything about ignitions so I'll have to take your word for it. I've never understood the instructions 'disocnnect the ignition and start the motor'. I've seen it in other posts as well as a form of troubleshooting other problems. If you disconnect the igition, how do you start the motor?<br /><br />But that said.....the guy I bought it from has put an aux key switch on it because the one in the shift controller didn't work. Maybe he's got something crossed or something.<br /><br />Mine doesn't die upon putting it in gear though. Only when you try to go further and increase any throttle. Could that be a short? Or is what your talking about happen the moment that it clicks into gear? <br /><br />Thanks for your thoughts.

 

[Chucky P]

Re: general fuel question

It sounds to me like you need to richen up your mixture I have a 76 85hp. Mine done the same thing. On the front of the carbs is the mix.screw. Set them till motor runs best, (one on each carb)then (on water) Turn screw counter clockwise 1/8 turn on each carb. Then try to increase throttle. repeat. Worked Great On mine Learned IT HERE Chuck YOU NEED MERC. MANUAL

 

[Yepblaze]

Re: general fuel question

Or remove offending carb(s) and clear the effected passages. (Jets and passages)

 

[zantz]

Re: general fuel question

Igintion issue, if it is a short, it can happen any time after you put it in gear. Imagine a wire with broken insulation, when you move the shifter it moves the exposed wire until it contacts something to short it out. If the guy who sold it to you put another key switch in, then he may not have covered the old wires in the control box, thus when you put it in gear by moving the shifter, you make that (or those) exposed wires either contact each other or something else which kills the motor.<br /><br />But this is just a therory.<br /><br />I'm no expert, but on my motor you can start it with the harness connected, then unplug it and you will not be able to kill the motor with the key until you plug it back in.

 

[jdstephwacotx]

Re: general fuel question

Thanks Zantz.<br /><br />Actually, he put the secondary ignition in and couldn't get it to kill (something about not knowing that the switch had to ground to kill) so he also had to put a separate kill switch in (he just used the horn button).<br /><br />Your starting to make me think I might have a mess inside the control box. How difficult is it to take apart and put back together?<br /><br />I think while I have most of the fuel system apart I will go ahead and rebuild the fuel pump. This kit looks cheap and from the other posts it doesn't sound that difficult.

 

[Chucky P]

Re: general fuel question

Before I took the control box a part . I would start my motor then unplug the plug(elec.)motor should stay running then, I would try to see if it died like before.If it does you know its not in control box.I might be wrong,But this will tell you one way or another Good Luck chuck

 

[zantz]

Re: general fuel question

I agree with Chucky, unplugging the electrical plug to the control box on the motor is an easy thing to do, and a good test.<br /><br />To answer your question about the inside of the control box, I would compare it to the inside of a carb. When you first take one apart, they look confusing, after you figure one out, their a piece of cake.<br /><br />Rebuilding the fuel pump couldn't hurt. Unless you do it wrong, like I did once on my dad's old Merc.

 

[jdstephwacotx]

Re: general fuel question

So I aassume that I'm going to take some sort of cover off of the control box and there is going to be this plug that you are talking about?<br /><br /><br />I haven't really paid any attention to this box yet.<br /><br />Since he relocated the key switch should I just leave the plug unplugged?

 

[Chucky P]

Re: general fuel question

No, Start the motor with motor running pull the plug on the side of the motor. this will isalate(misspell)the control box.then try to increase throttle. If it dies its should not electrcal Chuck

 

[zantz]

Re: general fuel question

Chucky is right. What he is saying is:<br />Take the cover off the motor<br />Follow the wiring harness where it enters the motor<br />Keep following the wiring to the motor until you find a big plug<br />Unplug this once before you start the motor in case it is hard to unplug<br />plug it back in and start the motor<br />Carefully (flywheel teeth can do nasty things to knuckles)unplug the big plug<br />put the motor in gear<br /><br />If it dies, it's not the control box wiring.<br />If it keeps running, it's the new key switch or the wiring in the control box.