1970 Merc 500 Thunderbolt 50HP, Need to replace fuel lines and add a Tach. Options?

[Roadblock]

So I took my boat out for the first time this year 4th of July to watch fireworks from Gun Lake here in Michigan.

When I primed my engine I had raw fuel dumping out of the motor so I popped the covers and discovered that I was getting fuel spraying out of the fuel line that connects the two float bowls. It was literally coming out from between the chrimped brass fitting and the hose. I was able to take the hose and wiggle it while pushing upwards and the leaked stopped. Even when I tried to over-prime the ball no fuel sprayed out.

I've taken it to the lake twice since then but I know I'm working on borrowed time before the leak returns.

I popped over to OldMercs and they do have the factory line in-stock for $55+ shipping but I'm wondering if there are any local hardware store fixes? Like brass fittings and fuel line that might cost less and be an acceptable fix?

I have a whole bag of parts I bought last year too. New water pump, I have two card rebuild kits, a fuel pump rebuild kit and a completely new engine wiring harness. The current wiring is questionable at best! It's all cracked and what looks like dry rotted but the engine works 100%, gets up and plans out well so I haven't messed with anything.

Being that it's running well I may hold off on the carb rebuild and maybe just replace the wiring, fuel lines and rebuild the fuel pump just because.

Engine compression tests at 140 across give or take 2~3 PSI so I'd say she is good.

So that said should I just buy a factor fuel line and call it good or piece something together and save some money?

Also I would like to add a tach. Does anyone sell the factory plug that connects to the throttle control on the 1970's Merc box? I know they had them but I've never seen one in person, only pictures. What all is required to install a tach? Would that plug do it or does something need to be done engine side?

I want the Tach so I can try to figure out which prop will get me the most top end speed. I have several Michigan Wheel props in various pitches but I don't know if I have the most effective one installed.

 

[gm280]

Paodblock, I honestly know how you feel about an engine running good. But you also know that it is borrowed time before it leaves you out in the middle of a lake one day as well. So I would take the needed time and money and make those needed repairs and play it safe. You would certainly hate to have an emergency out there and it did quit at that time. And knowing Murphy's law, guess when it would happen... JMHO!

 

[rookie456]

I bought my fuel hose and fittings from my local auto parts store, it was a lot less money than the kit. I also bought a faria tach online for around $50, and bought the wire harness that plugs into my control box from ebay. It was very easy to hook up on my motor, which is a 1980 80hp Mercury.

 

[Roadblock]

I ended up just buying the factory fuel line from Oldmercs.net for $54.99. I wanted to replace my factory original spark-plug wires and boots anyway so whatever!

Saved me from running around from parts store to parts store trying to explain to them what I needed, plus I Wasn't even sure what I needed size wise! I do remember one time I needed one of those brass T's for another project and it was a pain in the butt to find and very bulky once all the pieces were put together. I figured this way I know it's going to fit and I won't risk putting undo stress on the float bowls and risking cracking one of them. I know they like to crack if your not careful with the bolt and cover.

 

[Roadblock]

I can not locate the tach wiring harness anywhere. I don't see any on eBay.

 

[newhamburgboating]

if its just for testing props why not a tiny tach? or the cheap knock off's? I bought one over the winter from amazon and to the door was under $15. Worked fine for me to do the same thing.

 

[rookie456]

The harness that worked for my controls is part# 84-86396a 8. I saw 5 listed on eBay.

 

[Roadblock]

The harness that worked for my controls is part# 84-86396a 8. I saw 5 listed on eBay.

What year Merc control do you have though? Mine is a 1970. I think it's a 3 pin, I know from the wiring diagram, it's only has 3 wires.

 

[rookie456]

My engine is a 1980, I'm not sure what year the controls are, I think it is the control commander. If you search '46329 tach harness' on eBay a 3 wire harness shows up, not sure if it would fit your controls.