1968 Merc 20hp no start

[funnyboy]

I have a very pretty 1968 Merc 20hp 200 model that has very low hours or at least appears to be. I bought it last summer and used it once when it started up on second pull and ran perfectly for about an hour. This season I tried to start it but no go. It does not fire at all. I installed a new fuel pump diaphram, 90+ psi at both cyclinders (seems low), and a big fat spark at both plugs. The float assembly, upon inspection, appears to be free and working properly. <br />Here is what seems odd: when I pump the primer bulb, the bulb does not get hard and no fuel spills out of the overflow.....rather it runs out of the lower gear housing at the prop. No fuel is evident coming out of bottom of carb or float bowl. This motor ran great last year. What is going on here?<br />Thanks,<br />John

 

[Laddies]

Re: 1968 Merc 20hp no start

The inlet needle is stuck or one of the check valves in the fuel pump is not working

 

[JB]

Re: 1968 Merc 20hp no start

I suspect the reassembly of the fuel pump.<br /><br />You may be pumping the fuel directly into the crankcase.

 

[funnyboy]

Re: 1968 Merc 20hp no start

Thanks Laddies for the reply. Do you mean the inlet needle at the top of the float? If it is a check valve at the fuel pump is fuel backing up into the cylinders and out of the exhaust ports? The symptoms were the same before and after I replaced the fuel pump diaphram.<br />Thanks again.

 

[Laddies]

Re: 1968 Merc 20hp no start

Yes, was there any fuel in the float bowl? there should be, the float can be free and the needle stuck. With the top of the float chamber off you should be able to pump gas thru the inlet needle, with the bulb, if the pump is assmbled right--Bob

 

[funnyboy]

Re: 1968 Merc 20hp no start

I got the engine started today and am happy to have my old motor back. I replaced the inlet needle and seat. <br />Mercury lists the two small check valves as No Longer Available (NLA) so Im glad it wasn't that. The fuel pump is almost impossible to install wrong - it has a diaphram and 2 gaskets. I could use a newer fuel pump with the larger check valves that are still available, though, if I could scare one up.<br />Thanks again for the replies.<br />John

 

[Motor Boater Bill]

Re: 1968 Merc 20hp no start

You might check Grubbs for the fuel pump kit. Not sure, but they have a lot of "nla" parts for old mercs.<br /><br />www.oldmercs.com