2-line pressure tank question

[OMCfan]

I have a fuel system question involving a QD-16 and pressure tank. I tried starting it this morning and it does not appear that I am getting fuel to the plugs. I have put new points condensers and coils along with wires and boots and new plugs. I do have spark, which jumps about a quarter inch gap on both cylinders and very good compression. But, she is not firing and when I pulled the plugs, they were bone dry. I have not done any work on the carb, but it was extremely clean and no sediment in the bowl and there were no leaks. I have installed new fuel rated lines.

I did notice when pumping up the pressure that once the pressure built up some fuel was squirting out around the aluminum knob shaft. I have never used a pressure tank before so I do not know if this is normal or not. I did install new fuel line and new springs and o-rings on the female connector and a new cork seal around the tank pump housing. When pressurizing the tank fuel did enter and fill the glass sediment bowl on the carb.

Any advice appreciated! Thanks!

 

[F_R]

Fuel leakage at the primer pump shaft is caused by a bad seal where the pump shaft goes through the supports and diaphragm. Can be distorted supports, loose nut, and/or a corroded end on the pump shaft. The end has to be square (not corroded) where it meets the support washer, and you ought to put some sealer goop on it. Also, ,the knob is supposed to spin freely on the shaft. If it does not, you tend to rotate it as you pump, which unscrews the nut off the bottom.

EDIT: However, that leak is not keeping it from running, as long as the carburetor fills.

 

[OMCfan]

Thanks F_R, I checked the knob and it does indeed spin quite freely upon the pump shaft. So, it must be a bad seal, but from what I have read the motor should run with that as you said. The tank seems to be holding it's pressure so I am a bit stumped.

 

[HighTrim]

As stated, even if the tank wont hold pressure the motor should still fire, and run for a minute or so on the fuel already in the float bowl. For whatever reason, fuel is not getting drawn into the combustion chamber. Time to open the carb, clean and rebuild it.

As a test spray some premixed fuel into cylinder and pull it over. Does it now start briefly?

Also, just as a point of interest to you, pumping the primer button does not pressurize the tank. It simply sends fuel to the carb like a bulb on a newer single line tank would do. The tank does not pressurize until the motor runs for a bit, it is the motor that pressurizes the tank.

 

[OMCfan]

Thanks HighTrim,

I just got done partially opening the carb. The thing looked nearly spotless. I did not completely disassemble it, just separated the top and bottom halves. It still has the cork float and even the coating on that was intact and not flaking off at all. The needle valve moved by the float looked like new and I did spray both halves down with carb cleaner. I put it back on and no change. I'll keep tinkering and may as you advise need to just tear the carb apart and put in a new carb kit.

 

[OMCfan]

Can I buy a new seal for the primer pump, or do I need to buy the whole rebuild kit?

 

[oldboat1]

^^agree. You might pull out the sediment bowl and remove the filter, checking to be sure the bowl gasket is up there and intact. If the gasket is OK, put the bowl back without the filter, and try starting. I don't recall how much fuel you should see in the sediment bowl if the carb is fed properly -- thinking half full or less (probably less when it's running).

 

[HighTrim]

You can just buy the diaphragm. However, you may need a new gasket as well if it gets damaged taking the top off the tank.

Since you have the aluminum shaft/priming button, that is the earlier version, after that they went to the tanks with the black plastic button, that worked a little better.

When you install the new diaphragm, you must put sealer on either side of the diaphragm, where the shaft goes through the hole in the diaphragm.

 

[HighTrim]

Here is a diagram so you can visualize what we are talking about.

 

[OMCfan]

Thanks gentlemen, I ordered a carb kit It is hard for me to tell if the filter in the bowl is clogged or not as it looks very clean but I will try to run it without the filter and see if that solves any issues. It did seem that it took a fair amount of pressure to get the fuel to start filling up the glass bowl, so maybe the filter is badly clogged and I can't see it.

 

[OMCfan]

Parts are soaking in a chemical carb bath. What sealant do you recommend for around diaphragm where the shaft runs through?

 

[OMCfan]

I'll have my carb kit this afternoon, does anyone have a diagram of a QD-16 carb. I just want to be sure that I put it together properly. I noticed in the kit the needle has a notch and comes with a tiny spring pin. My original needle does not have this...I did order the proper kit but wondered why the difference.

On a separate note...I forgot to mention when pulling the rope to try and start the motor, the rewind slips on occasion. I checked and made sure that the plate on top of the flywheel is tightened down the flywheel was put on any tightened to 40lbs torque and I can't see anything obviously wrong on the rewind, but I am a bit new to this restoration thing.

 

[F_R]

The original float valve had a metal tip. Everything you buy now has a soft tip for better sealing. But when the soft tip came out, it didn't take long to discover they would stick up in the seat. And the cure is that little spring clip to drag the needle off the seat. Problem fixed.

 

[OMCfan]

Thanks for the information. I am glad that I am rebuilding the carb. Although the carb was pretty clean, the valve packings were hard and very tough to remove and at least now I will know what condition the carb is in when am done and hopefully my little motor will come back to life. I will have to try and fix the tank problem later so I am not getting gas all over the tank.

I think you may be the gentleman that I bought my timing tool from. I enjoyed using it!!!

 

[OMCfan]

Okay gentlemen, I finished installing the new carb. kit and I have the carb. mounted on the powerhead and will let the sealant have 24 hours to fully set and then I will give it a go. I set the slow speed needle 1.5 turns from fully (gently) seated and the high speed needle is 1 turn out from seated...that is what I think are the correct initial settings. So, I will see what happens. I did leave the ceramic filter out as it is likely that it is all gunked up on the inside of the pores. I did hang on to it just in case though. It looks great indie and out but what maybe in between who knows.

 

[HighTrim]

Can you post a pic of the bottom of the starter assembly. Did you figure out how to install the clip on the float arm?

 

[HighTrim]

Start the high speed at about 3/4 out from seated, it will end up being about 1/2 by the time you tune it, 9 times out of 10 anyways.

 

[OMCfan]

HighTrim,

I am trying to figure out how to shrink the picture so the site will accept it. I will try to work on that, but as far as I can see all the moving engagement levers and corresponding springs are present and intact. also all of the teeth are present on the piece on top of the flywheel.

 

[HighTrim]

Its ok. Perhaps only 1 or 2 of the 3 pawls is engaging when you pull on the rope. Remove the starter, flip it upside down, and watch the pawls while you pull on the rope. They should engage out, then retract when the rope retracts. Sometimes, they simply need some lube to function correctly if sticking.

 

[OMCfan]

Okay I have an update, I put it in the tank primed the line until I felt there was likely enough to fill the float chamber and gave a few pulls and it fired and ran for a few seconds. I did this several times with a lot of work and the last time she ran for about 30 seconds and died.

Problems that surfaced. I have a rub somewhere between the mag. plate and flywheel so I am going to have to check that out and see what the deal is. Second, I am leaking a lot of fuel now out around the primer pump so I am definitely going to have to deal with that problem. Third, as previously mentioned, I dd not reinstall the ceramic filter as I could not tell if it was clogged or not.

As always advice is welcome!