Just discovered this forum after buying a 1983 18' Bonito trihull last week. Nice work.
Anyway, got this 1988 70 Merc EPTLO on the boat. It had apparently sat for a while, and the oil injection system was disconnected. Fired it up the day after I bought it, and the engine would stall out as soon we'd open the throttle.
We immediately suspected a carb problem, opened the WME carbs, and replaced the gasket, made float adjustments, and cleaned all the parts.
Afterward, the stalling problem was still evident until we turned out the low speed mixture screws nearly as far as they'd go (clearly way too much).
At that point, when running at wide open throttle, the engine would no longer stall, but we also weren't getting the necessary power to get on plane.
After bringing her back in, we opened the fuel pump, saw plenty of old gasket material and stretched diaphragms (with pinholes in them), and installed a diaphragm kit. We also reconnected the Oil Injection system.
We ran it today, it fires up great and the stalling is gone.
However, we are still having the problem with reduced power at WOT. I forgot to mention that the engine will seem to get plenty of power intermittently, with it bogging down before getting on plane. Squeezing the primer bulb during operation also doesn't seem to make much of a difference, and the bulb maintains what appears to be proper rigidity. I'll also add that we replaced the fuel line and primer pump.
While we were underway, just screwing around, I decided to push the key in, and the engine seemed to get all the power it needed at that point, putting us promptly on plane. We ran it for a bit like that (with the key depressed) and it did great. Oil injection seems to be functioning fine, and the maintenance we did seems to have had a really positive effect.
When you depress the key, the enricher valve does click, and the engine does start up fine. I followed the procedure for testing the enricher valve (from the Merc service manual), and everything seems to check out.
It seems to me that since the purpose of the valve is to dump fuel from the top carb's bowl into the other carbs, that the bottom carbs are only functioning properly when you manually feed them fuel via the enricher valve.
I'm sort of stumped here, but feel like we're really close to a resolution.
Any insight into this problem would be super helpful.
Bill
Anyway, got this 1988 70 Merc EPTLO on the boat. It had apparently sat for a while, and the oil injection system was disconnected. Fired it up the day after I bought it, and the engine would stall out as soon we'd open the throttle.
We immediately suspected a carb problem, opened the WME carbs, and replaced the gasket, made float adjustments, and cleaned all the parts.
Afterward, the stalling problem was still evident until we turned out the low speed mixture screws nearly as far as they'd go (clearly way too much).
At that point, when running at wide open throttle, the engine would no longer stall, but we also weren't getting the necessary power to get on plane.
After bringing her back in, we opened the fuel pump, saw plenty of old gasket material and stretched diaphragms (with pinholes in them), and installed a diaphragm kit. We also reconnected the Oil Injection system.
We ran it today, it fires up great and the stalling is gone.
However, we are still having the problem with reduced power at WOT. I forgot to mention that the engine will seem to get plenty of power intermittently, with it bogging down before getting on plane. Squeezing the primer bulb during operation also doesn't seem to make much of a difference, and the bulb maintains what appears to be proper rigidity. I'll also add that we replaced the fuel line and primer pump.
While we were underway, just screwing around, I decided to push the key in, and the engine seemed to get all the power it needed at that point, putting us promptly on plane. We ran it for a bit like that (with the key depressed) and it did great. Oil injection seems to be functioning fine, and the maintenance we did seems to have had a really positive effect.
When you depress the key, the enricher valve does click, and the engine does start up fine. I followed the procedure for testing the enricher valve (from the Merc service manual), and everything seems to check out.
It seems to me that since the purpose of the valve is to dump fuel from the top carb's bowl into the other carbs, that the bottom carbs are only functioning properly when you manually feed them fuel via the enricher valve.
I'm sort of stumped here, but feel like we're really close to a resolution.
Any insight into this problem would be super helpful.
Bill
