1978 70HP Evinrude Fuel Pump

[landgrj]

I am replacing the internals of the fuel pump on my '78 and took the part numbers from the engine and diagram on marine engine. Ordered the Sierra rebuild kit for this year's pump and started tearing down the old one when I ran into an issue.

The old pump has 2 reeds instead of check valves in the plastic body. It is also ~.25" smaller than the parts I ordered for it. The gasket and diaphragm bottom holes don't line up. See attached photos.

I am unable to find any information on the pump that I do have, or where I could order rebuild parts from. Any information is appreciated.

The mounting gasket was missing when I took the fuel pump off as well which leads me to believe the previous owner swapped this pump on, not sure if the check valves vs reed design has any effect on fuel delivery. The engine runs well except for the occasional bog on hard throttle.

Thanks,
Joe

 

[racerone]

The mounting gasket is NOT needed on the 70 HP models.-----Post a picture of the diaphragm------I doubt the fuel pump is the issue.----What other trouble shooting was done if any.-----Is there bogging when your co-captain operates the manual fuel pump?----Tried running with another fuel tank?-----Post the actual compression test values.

 

[landgrj]

I will post a picture of the diaphragm tonight, after removing the gaskets and diaphragm I would like to replace those components. I am unable to find the correct parts kit for this.

History:
Bought the motor used to repower late last year. Compression of 120 on all cylinders. Did a full service on the carburetors, new gaskets/floats, soaked all parts in carb cleaner. First time out it had issues getting to full speed, would consistently run at 10mph full throttle.

Trailered it and looked it over for a few weeks. Verified TDC, new spark plugs and changed rectifier as the battery was not charging. Did a link n sync per instructions on here.

Took it on the lake again and set idle once in water. Runs great at idle and top speed but has an occasional hiccup when going full throttle. Sometimes it gets on plane immediately other times is bogs a bit and then pull off the throttle and ease it up and it goes again. Running 5100 rpm at full throttle.

Fuel tank is original with the boat, 1972. Fuel lines were replaced about 10 years ago. Boat has only seen mid grade or premium without ethanol. Can buy a separate fuel tank and try running direct from there once it warms up a bit more.

I can take someone with next time to operate the bulb.

 

[landgrj]

Here is a photo of the diaphragm.

 

[racerone]

Any holes or tears in it ?

 

[landgrj]

No holes or tears.

 

[racerone]

See post#2---Are you aware of issues with gaskets on the exhaust manifold.----Allows water to leak into the engine.

 

[landgrj]

I will review the gaskets and see if there are any visible edge defects on the gaskets.

For the fuel pump do you know of a rebuild kit for this specific pump. I would like to replace the gaskets that I have taken off already.

 

[saltchuckmatt]

My guess is timing or carb set slightly lean. The above statements should be checked first.

OEM gaskets should be easy to get, try another pass online or I boats.

 

[Crosbyman]

why not not just buy a new pump... some don't cost much more than gasket kits. Try a cheap one on Amazon ... I know it is not OEM (sacriledge) but it will get you going.

 

[landgrj]

Thanks for the info, carbs don't have any adjustments, they used fixed jets. I verified TDC matches flywheel pointer.

I could buy a fuel pump but I'm not down currently, just wanted to investigate the fuel pump as it's condition is unknown. Seems it was in decent shape and just want to replace with new seals. Found the kit on marine engine finally, it's 18-7820. This older fuel pump style has the shoulders and a slightly smaller profile overall.

Anyone have info on how well the little reeds hold up in these? Did they make the change to check valves for cost or performance/longevity?

I'll be ordering the kit and go on to investigate some of the other possible causes of bogging as well.

 

[racerone]

About the only thing that can go wrong is the DIAPHRAGM -----Believe it.

 

[ct1762@gmail.com]

Thanks for the info, carbs don't have any adjustments, they used fixed jets. I verified TDC matches flywheel pointer.

I could buy a fuel pump but I'm not down currently, just wanted to investigate the fuel pump as it's condition is unknown. Seems it was in decent shape and just want to replace with new seals. Found the kit on marine engine finally, it's 18-7820. This older fuel pump style has the shoulders and a slightly smaller profile overall.

Anyone have info on how well the little reeds hold up in these? Did they make the change to check valves for cost or performance/longevity?

I'll be ordering the kit and go on to investigate some of the other possible causes of bogging as well.

the old pumps with the valves were and are nearly indestructible. unless they are stuck or rusted, you can expect zero issues. just poke and pull them a teensy weensy bit to make sure they move.
Racer mentioned exhaust plate gaskets leaking. the whole thing gets very hot and is in 3 separate pieces. later years it was just 1 as the rest was cast-in to the block like a 2 cyl looper. the only way to know if you are getting water in cylinders is to remove cylinder head. if so, you will need to remove powerhead to fly-cut inner exhaust plate flat and replace gaskets. lots of surface area to clean. fun! honestly i'd do it anyway as preventative maintenance. that with a head gasket, cover gasket and t stat/poppet valve only takes an afternoon