140 problems I have tried everything

[1978starcraft140alpha]

I have a 1978 Starcraft American that I just picked up a few weeks ago for a hot tub that had been laying around in my back yard. So I dont have much in this boat. The boat hadn't ran for 2 years before I got it, and the owner had just drained the water jackets and block from winterization when I first went to look at it. He had mentioned that it ran when he parked it, although he felt the carb would need rebuilt. So the first thing I did was rebuild the 2 barrel rochester, Transom bearing, u-joints, bellows and shifter cable, then replaced the coil, cap, and condenser. She fired right up and away we went to the lake =-) so I thought. The shifter control stopped working before I could get her to plain out. Babied it back to shore, took it home, rebuilt the controls, they are working great now. Went to take it back to the lake, so I stopped and put some fresh gas in it, now the gas that was in it was old, about 1/4 tank, I added STP gas treatment and filled it. Well I got it to the lake and I smelled a little gas, and the boat would start, but not run. Out on the water, it would WOT at about 1600 rpm, in or out of the water. On the water, every now and then, the engine would surge and run upto about 3200 rpm but then back down to 1600. So I trailered it and took it hom and tore the carb back off and tore it back down and clean as a whislte, it's not the carb, accelerator pump, everything is working well there, Now for compression, 97-97-97-100lbs just tested it cold and got those readings, I am stumped, I was hoping for no compression on two cylinders so I could just replace the head gasket and move on, but now I am stumped. Lastly Spark, I have it, I can time an engine, and this engine doesn't seem to be lacking in spark. This is my first boat, thus my first marine engine, I understand how the engine works, but am still at a loss. Maybe something in the manifold? Any help would be greatly appreciated.

 

[ziggy]

Re: 140 problems I have tried everything

have you tried any of this stuff. from the adults only thread at the top of the i/o page. http://forums.iboats.com/showthread.php?t=295070
the compression is right on the edge of non serviceable too i believe..

 

[Schmoe]

Re: 140 problems I have tried everything

Could be the fuel pump, check pump pressure. Could also maybe be your choke setting. Sure sounds like it's fuel related. Have you checked the fuel/water separator, the in-line fuel filters? Compression does seem a little on the low side, regardless of temperature.

 

[jennis9]

Re: 140 problems I have tried everything

we just had the same problem:

We rebuilt the carb and the throttle plate was worn - so we're on to a new/rebuilt one.

Also, check to see if you have the correct ignition wires. We went to WM and they gave us electric ignition wires and we burnt out a few plugs and it delayed diagnosing the real problem since we had two issues going at once.

 

[1978starcraft140alpha]

Re: 140 problems I have tried everything

Wow thank you guys! You have given me a lot to think about. I ran down the list on the adults only page, most of which was a huge help. I am not sure that maybe the intake isn't part of my problem. When I was rebuilding the carb, and had the plate off, I did notice that it looked like someone had over tightened the air mixture screws to the point that it left 2 dimples on the inner port of the intake plate. I don't think that is the direct issue to the problem I am having now, but worth replacing I bet. I did check the in-line filter in the mechanical fuel pump, but not sure exactly what the pressure is yet but it was a new filter and it seems to be pumping with plenty of pressure. Ok I ran her on muffs this morning and all 4 cylinders are firing now, although #1 plug was darker and just a bit moister than the other 3. I am getting a strong spark from that cylinder, deal is when the engine is running at idle, I can pull plug #1 and nothing noticeable happens, I mean the engine seems to not miss a beat like that cylinder is dead, but when I shut it off, and pulled the plug, it was as dry and cleaner, like the other 3. Is it possible, that I need to just, run it to the lake and run the crap out of it, until it burns the plugs clean and possible blow all the crap out of the head of the engine(it sat for 2 years)? Or, does this possibly mean that the valves on that cylinder are so far gone, that the little bit that that cylinder contributes, just doesn't benefit the engine enough to change the idle when you pull the plug wire? Thank you all again for all the help and I am sorry for all the new-B boat questions.