Old Merc 1500 cranks, won't stay running

[brufo]

I have an 1979 in-line 6 that cranks right up, runs fine for about 5 - 10 seconds, dies. If I let it sit several minutes it cranks right back up, runs again then dies. If I try to imediately restart the engine it will fire and crank but not run for more than a second or two. I have rebuilt carbs multiple times, replaced fuel pump, plugs are getting fire, compression is good. I am out of ideas other than maybe the timing, but it ran fine for several weeks, then just quit running.

 

[JB]

Re: Old Merc 1500 cranks, won't stay running

It is always useful to find out what is wrong before you start replacing/rebuilding/overhauling stuff, Brufo.

Sounds like you have a fuel supply problem. The engine is burning up what is in the carbs faster than the pump can replace it.

Have you tried pumping the primer bulb when you start it? Are there air leaks in the hoses from the tank? Is the line from the tank pinched or twisted? Is the tank pick-up restricted?

You could have saved yourself a lot of expense and trouble if you had troubleshot rather than fixing stuff that wasn't broke.

Check out your fuel supply and let us know what you find.

Good luck, and welcome to iboats.