1974 50hp Mercury

[Reelfoot]

Recently purchased a Sea Spirte with a Thunderbolt 500 50hp 4cyc motor. Question is will I be wasting my time to get it running again. It has sat for over 4 yrs and I'm sure it will need fuel pump rebuild and also carbs. Let me know what y'all think

 

[jimmbo]

First thing is to check that there is Oil in the gearcase, A new Water Pump Impeller would also sound advice, as you are risking an old Impeller breaking and pieces plugging up the cooling system. A compression check is needed, then you will know if it is even worth spending Time on it, let alone Money

 

[Reelfoot]

I checked out the gear box. The oil in the gear case was thick , not milky , and the shift assy works properly. The prop is bent up but maybe straightened. After working further I found the reason why they sat the boat in a field where I found and bought for only $100 bucks. But anyway I found a sheared bolt holding the fuel pump to the block. Looks like they changed the diaphragm and over tightened the bolts. No biggie there. I have another question. Can I bypass the fuel pump with a electric fuel pump ?

 

[Fuelhauler91]

I sure wished this thread would have continued past this point. I’ve got this exact engine that I can’t get to idle now, it’ll run half and wot, but not any less than 1500 rpm really.

 

[airshot]

I sure wished this thread would have continued past this point. I’ve got this exact engine that I can’t get to idle now, it’ll run half and wot, but not any less than 1500 rpm really.

Need more information on your issues and motor. Start with a compression check, then a spark gap check. When were the carbs rebuilt last, was a factory rebuild kit used ? Do you have a factory service manual to make a proper link and sync for the carbs and ignition ? With your these to start, can't help you.

 

[1960 Starflite]

I sure wished this thread would have continued past this point. I’ve got this exact engine that I can’t get to idle now, it’ll run half and wot, but not any less than 1500 rpm really.

I purchased an old pontoon boat to get the trailer and 850 (1975) Mercury. It also wouldn't idle slowly by ear (I didn't have a Tach). I did a link n sink and found that previous owner had the timing belt advanced one tooth. Timing sets the idle speed.