1963 Johnson 5.5 CD-20: Rebuild Fuel Pump?

[Pixelauthor]

Hi all! I'm well into my first rebuild: a 1963 CD-20 that was my childhood motor. Lots of history in it, so it's really cool to be rebuilding with my son. I've already rebuilt the carb, checked the impeller (surprisingly intact and very pliable), changed the lower unit oil, checked the points and coils, and replaced some VERY crumbly fuel lines. I've yet to start it in a tank or on the water, but wanted to ask about the fuel pumps on these old Johnsons.

The consensus seems to be that rebuilding is less common than just replacing with a newer, more modern square pump (like https://www.amazon.com/dp/B07MBF5S4D/ref=cm_sw_em_r_mt_dp_U_YPczDb3RQWQT1). Is this the best course of action if I run into issues? I've disassembled the pump and cleaned out the minor oxidation I found, and reassembled. The membrane and gaskets seemed in pretty good condition, but I'm not sure how they'll perform. OEM pump part is #0378805, if that helps. Thanks!

 

[racerone]

You should install a new impeller.

 

[Daviet]

If after you cleaned and inspected the old pump and it operates properly, use it and move on. racerone is correct, you should replace the impeller.

 

[walker45]

I am by no means an expert nor do I pretend to be but I did find it worthwhile to read the reviews on the cheap aftermarket fuel pumps before ordering one. My .02 cents worth is to if possible rebuild your old one or try to get it working and save the cheapos as a last resort.

 

[jimmbo]

If the Diaphragm is soft and Flexible, you should be OK. I did say "should be". As we don't know how old the Diaphragm is, it might not react well with today's sad excuse of what is called Gasoline, so replacement might be wise

 

[F_R]

If it still has the original 378805 pump, parts have been unavailable for that thing for many years now.

 

[Crosbyman]

well if the check valves are ok you may want to try cutting up some nitrile to make the new parts

cheap pumps have worked for me but…. my last one may be a source of problem...my current 9.5hp does not run good at HS
more testing needed…. as I suspect the pump

 

[Pixelauthor]

Thanks everyone - your advice is invaluable. The powerhead is still off (waiting for my new exhaust gasket) so I'll pull the lower unit back down and install the impeller per your recommendations. I'll tank test before I buy a new pump and let you know how she runs.

 

[Pixelauthor]

Any advice on getting the roll pin at the top of the drive shaft to release? I used a flat punch, and it won't budge. Going to soak for a bit in WD-40 and have a go at it with some vice-grips I think.

 

[F_R]

Whoa, why do you want to take it out?

 

[oldboat1]

Needs it out to slide on a new impeller, doesn't he? (Maybe been too long, or memory is too short....)

 

[racerone]

No----You pull the driveshaft out of the lower unit.-------Pull the impeller off the bottom.-----That is if it has the original lower unit with the slip clutch !!!!

 

[Pixelauthor]

That's a lot of exclamation points! racerone, as far as I'm aware, mine doesn't have a slip clutch. Perhaps not original, but in the exploded views I've seen the 1963 5.5 Johnsons don't have them.

In any case, the lower end of the drive shaft also has a roll pin...covered in oil from the gearcase. I'll take the upper, easily accessible pin over that one. I was able to get tease the upper roll pin out with some WD-40, vicegrips and time last night. Impeller is replaced now, plan to re-attach the power head tonight!

 

[Crosbyman]

make r certain you have the correct base gasket if new… patterns differ

 

[racerone]

Well ---Sorry but your 63 model ( if original ) does have a slip clutch.-----Item 10 ---376073------It is found underneath the water pump.---Under that bearing housing.---

 

[Pixelauthor]

Ahhh, that explains it. It's not labeled in the schematic I was looking at, and coated in oil, it just looks like part of the drive shaft. Sorry for the confusion - I do indeed have one. Power head is back on, fuel lines replaced. Just waiting on a fuel filter and I'm going to tank-test this bad boy!

 

[racerone]

Pulling the driveshaft out of the slipclutch makes changing the impeller " easy "-----Note-----There is no adjustment on the shift rod.----Factory did a good job of engineering / building it so that 50 years or more later folks would not have trouble with worn / mis-adjusted stuff.

 

[F_R]

Yep, a '63 has a slip clutch (shock absorber). The drive shaft simply pulls out of it, No roll pin. So we don't know what pixelauthor has. And I've had at least a thousand or more of them apart.

 

[racerone]

Just simple stuff in my opinion.

 

[oldboat1]

Back to the fuel pump, then. There is quite a price range for replacement pumps, if it comes to that.