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Mariner 70hp 1980 - fuel pump, filter & line maintenance

naio83

naio83

New member
Hi all, I was making some maintenance to the fuel_line and I would love some pieces of advice on these 3 topics:

fuelLine.png


1) This engine has a circular fuel filter with a metallic part, red square (part 32), inside which replacement is very hard to find nowadays (at least where I live) so the advice that I have received is to only wash it with fresh fuel. I would like to know if it is a good idea to add an extra fuel filter earlier in the fuel line. Maybe after the primer bulb and before the female connector to the engine or inside the engine before the fuel pump (part 18)?

2) I am starting to replace some hoses as they have more than 10 years now (all PVC 5/16″ (8 mm) up to now for what I have seen), I have no leaks on the hoses but when I squeeze the primer bulb there is a leak in the engine line connector (part 21). I have found in a local reseller the female part that connects to the engine but not the one that is screwed in the engine (part 21). I would try changing the female part of the connector that comes from the tank fuel line, but in case that this doesn´t solve the leak, any suggestion?
I have seen that some engines have removed the connector in the engine and connected the fuel pump with a hose directly with the primer bulb, I don't like the way it looks and the fact that I can´t detach the hose from the engine but It may solve the leak.

3) I have ordered the diaphragm kit for the fuel pump (part number 55278A 4) and I will make the replacements for the first time. I have 2 doubts here, the first one is the fuel pump in the green square has 3 nuts. I guess that some of them are holding it to the engine and some are holding the pump together so I don´t want to unscrew everything and only the ones that attaches the pump to the engine so I can work in the pump in a table quietly. Any advice on which to unscrew for removing the pump in one piece?
The second one is that I know there is a spring inside the pump that has to be re assembly with care, so any advice here will be much appreciated!



Thank you all in advance!
 
You can use a simple, in-line can filter from NAPA.

Can't see from the photo if your setup has water cooling the fuel pump. If so, you need to block that flow of so all of the water goes to the block. These motors are notorious for frying their top cylinders.

Jeff
 
Just clean that filter on the block ,it's stainless steel,; undo the 3 bolts holding the fuel pump to the block and replace the components - gasket, diaphragm, gasket and reinstall but don't tork the bolts too hard (they're going into aluminum). The female (tank end) has an o-ring in it this seals the unit so all you should need is this component. the male connector and the filter screen are available just check out oldmercs.com.
I have those items on my engine and have done those procedures.
 
Just got this from my manual; if fuel leaks from the engine side when the connectors are separated it's probably the O-ring.
male-fuel-connector.jpg
 
fastjeff said:
You can use a simple, in-line can filter from NAPA.

Can't see from the photo if your setup has water cooling the fuel pump. If so, you need to block that flow of so all of the water goes to the block. These motors are notorious for frying their top cylinders.

Jeff
Click to expand...


Thank Fastjeff, I have made the full rebuild of the pump, changed all the hoses and cleaned the filter. The screen of the filter was in good condition, so I am doubting if adding an extra filter before the pump would be a good idea, would the pump have enough power for an extra filter?I do not have NAPA here, but I can use some in-line filters to try.
 
Quicksilver said:
Just got this from my manual; if fuel leaks from the engine side when the connectors are separated it's probably the O-ring.
View attachment 28359
Click to expand...



Great! I followed your advice (and watched and read many articles) and did the full rebuild without problems. The fuel pump was really stuck to the block and it was really really hard to lose it, but finally it was possible (cleaning the gasket from the pump and the engine block was tricky also).
It has been there for years. I replaced the kit with the O-rings, hoses and so on. I found that the fuel hose connector IN the pump from the tank and OUT to the filter were a little bit thinner than the other ones (I had 8mm / 5/16 hoses and I think that they were 6 mm ).
Concerning the leak in the connector, it happens in the bound of the 2 connectors, I can find a non- OEM for the female part, but not sure for the male (oldmercs.com doesn't send to where I live).
I will keep on trying to solve this leak, but the rest of the procedure went great.
Thank you again for your help!
 
naio83 said:
Thank Fastjeff, I have made the full rebuild of the pump, changed all the hoses and cleaned the filter. The screen of the filter was in good condition, so I am doubting if adding an extra filter before the pump would be a good idea, would the pump have enough power for an extra filter?I do not have NAPA here, but I can use some in-line filters to try.
Click to expand...

Wal-Mart sells fuel filters in their marine section for $5.
 
bigjohnson said:
Wal-Mart sells fuel filters in their marine section for $5.
Click to expand...


I will try to find some for 2t and premix fuel. I live in Argentina, we have Walmart here but they don't sell marine stuff... And there are few things that can be shipped. Anyway, there are those generic filters I will get one.
I was worried about not damaging the pump by adding an extra filter.
Thank you for your help!
 
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