1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

[Munrofuryowner]

Mercury 65hp has trouble starting. Cyl compression and sparks ok but sounds like is not getting fuel. Will cut out odd time when running. When pump bulb and then turn electric start somtimes see fuel floating in the water.
Is this a torn fuel pump diaphragm or something to do with carbs?

Any advice appreciated

 

[Mnace01]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

My 75 650 has the exact same problem. Haven't figured it out yet, it will start in driveway and then not when I get to the lake. When I tilt the engine up, fuel runs out of the carbs as well.

 

[Mi duckdown]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

An OEM Merc Manual would serve both of you alot of info. Worth every penny. Have serial number when ordering. Mercury Marine.com

 

[Munrofuryowner]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

Mnace01
If I find out what it is I will let you know, have found a smaller repair shop where guy seems to know what he is doing have booked a visit for two weeks from now

Will also be looking into getting the manual for own repair but cheapest I have found for OE is $100.
At website seaway they do have parts catalogue and exploded diagrams online so have been using that for now.

 

[Mnace01]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

That sounds great. I got a brand new repair manual for mercury on Ebay for $28 shipped. You should look there before spending $100.

 

[Mnace01]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

I looked up the place for a manual in my E-mail. The SELOC repair manual is only 22.95 brand new from them. Here is the website http://bustersmarine.com/manuals/manuals.html

 

[MacDaddy21]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

Mnace01 and Munrofuryowner:

If fuel is leaking out of the carb when you tilt the motor up, the float(s) in your carb(s) are probably not sealing against the needle and seat. This
could mean new floats and new needles and seats. All are cheap and can be found at your mercury dealer. If you tear the carbs down that much,
you might as well clean and rebuild them, and a fuel pump rebuilt would not hurt either. The diaphragms in the fuel pumps will wrinkle over time,
and a new diaphragm can really help. The fuel pump rebuild kit will also come with new check valves, which make a difference. I suggest getting a manual if you are not familiar with your motors or outboards altogether. Good luck

 

[CharlieB]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

Check here to see if your manual is still available for download.

http://forums.iboats.com/showthread.php?t=309079

 

[Mi duckdown]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

I have bought lots of OEM manuals on ebay and craigslist.
Just need to Know the serial number. .02

 

[Mnace01]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

I rebuilt the carbs and took it out yesterday, after a bit of adjustment on the idle screws, it runs great. Had it out over an hour with no problems. Another thing is making sure that the
air vent on the fuel cell is fully open. I have had weird spouts of the boat dying only to realize that my son hadn't opened up the air vent enough.

 

[Munrofuryowner]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

Mnace1
Glad to Here you fixed your issue. Where are you buying your repair kits from? I will be doing the carbs and fuel. Looking at the motor more it I should probably rewire it - frayed

Will be doing both the carb

 

[Mnace01]

Re: 1970 65hp mercury thunderbolt outboard has trouble starting fuel pump?

I ordered the needles, seats, and floats from boats.net I found all the gaskets at a local marina that services mercury. Nobody really sells a carb kit for our engines anymore, so you have to buy them all piece by piece. All together it cost about $55 plus I purchased a gallon of carb cleaner with basket so I was able to soak each of the parts for about 8 hours.