More 1979 mercury 140

[cyknife]

So I took a chance and gave money (not that much) for a boat based only on seeing it idling on muffs and its overall fair shape. The owner said he ran it 5 times this season with the last trip out having only been able to make 18mph after making 50mph previously. He thought it was a fuel delivery issue. The motor idles fine and it does not spit fuel out the carbs so I figured it hadn't sucked a reed, how bad could it be. The motor starts easily too.

I found a few fuel hose connections missing clamps, remedied those and got the boat up to 31mph. (Tach is not hooked up yet so...) Brought the boat home and did a compression test resulting in:

#1 115
#2 120
#3 120
#4 120
#5 120
#6 115

I forgot to open the throttle to "full" but those readings seem OK.
Seafoam is next and then a spark check. What next, carb rebuild? Fuel pump? The tank is in the bow so would that require an intermediate pump?

Also the motor wiring is typically rotten. Don't know if that would manifest as a power loss.

http://i252.photobucket.com/albums/hh39/cyknife/P1000251.jpg
http://i252.photobucket.com/albums/hh39/cyknife/P1000250.jpg
http://i252.photobucket.com/albums/hh39/cyknife/P1000245.jpg

Any ideas would be cool!!

 

[daveswaves]

Re: More 1979 mercury 140

So I took a chance and gave money (not that much) for a boat based only on seeing it idling on muffs and its overall fair shape. The owner said he ran it 5 times this season with the last trip out having only been able to make 18mph after making 50mph previously. He thought it was a fuel delivery issue. The motor idles fine and it does not spit fuel out the carbs so I figured it hadn't sucked a reed, how bad could it be. The motor starts easily too.

I found a few fuel hose connections missing clamps, remedied those and got the boat up to 31mph. (Tach is not hooked up yet so...) Brought the boat home and did a compression test resulting in:

#1 115
#2 120
#3 120
#4 120
#5 120
#6 115

I forgot to open the throttle to "full" but those readings seem OK.
Seafoam is next and then a spark check. What next, carb rebuild? Fuel pump? The tank is in the bow so would that require an intermediate pump?

Also the motor wiring is typically rotten. Don't know if that would manifest as a power loss.

http://i252.photobucket.com/albums/hh39/cyknife/P1000251.jpg
http://i252.photobucket.com/albums/hh39/cyknife/P1000250.jpg
http://i252.photobucket.com/albums/hh39/cyknife/P1000245.jpg

Any ideas would be cool!!

If the tank is in the front of the boat you can almost be guaranteed that the problem is fuel delivery. The fuel pump would certainly be worth rebuilding and carbs cleaned out. If the fuel lines have deteriorated crud may have plugged the high speed jets.

 

[daveswaves]

Re: More 1979 mercury 140

Just had another look at your pics, great boat by the way, the pic of the engine shows 1/4 fuel line. 3/8 is preferred, 5/16 is ok, 1/4 is too small.

 

[cyknife]

Re: More 1979 mercury 140

GOOD CALL! I know the last owner replaced the aged fuel lines but I didn't think of or notice they are the wrong size!!!! I will address that problem asap. Thanks for the compliment on the boat. It is a 75 Kona. Its fun even at 31mph!

awsome

 

[cyknife]

Re: More 1979 mercury 140

Further checking... boat has 3/8 from the tank to the bulb 5/16 from bulb to fuel connector then a dose of 1/4 inside the housing. Ordering pump rebuild kit and will change out the 1/4 for 5/16 under the cowl. Noticed an inline fuel filter under splash well, could be a restriction. Hmmmm that filter.....