Re: making popcorn 1999 fitch 150
I've heard the "popcorn" story before, but never while the engine was running on a flushing device. Does the engine do the same thing when running on the water? If it does, 3 things need to be checked.<br /><br />1. The fuel lift pump diaphragms: Remove the pulse hoses from the crankcase fittings and one at a time pressurize each hose to 10 psi. If it holds 10 psi for a few minutes, increase pressure to 15 psi. Again, it should hold. Repaet the process on the other hose. If either leaks down, replace the lift pump. Use a gearcase pressure tester for this test.<br /><br />2a. Install a fuel pressure gauge to the test fitting on the fuel rail. Pump up the primer bulb. Turn on the key switch. While the electric fuel pump is running, you should see between 20 to 30 psi (ideal is 25 to 28). Once the electric pump shuts off, pressure will drop 3 to 5 psi and what ever it drops to, it should hold for 10 full minutes with no (or very little) leak down. If pressure drops down, all the fuel injectors should be individually pressure tested. Once you've determined there is no leak-down, pump up the primer bulb again and take a large sample of fuel from the test point. Catch the fuel in a clean container. You're looking for water in the fuel. If you find water mixed with the fuel at the test point and You're 100% positive there's no water in the boat fuel system and the the fuel filter, you may have the vapor seperator leaking cooling water into the fuel portion of the canister.<br /><br />2b. IF YOU NEED TO PRESSURE TEST THE INJECTORS: Bleed off any pressure in the fuel rail and disconnect the rails from the injectors. You will need 2 special fittings, one for the outlet, which will be "capped" and one for the inlet which attaches to the gearcase pressure tester. Each injector should hold 30 psi for 10 minutes. Absolutely no leak-down.<br /><br />3. While the engine is running and "making popcorn", remove the vapor seperator vent line from its fitting on the crankcase cover - DON"T remove the vent hose from (at) the vapor sep, if you damage the fitting, you've got an immediate $500 problem. If you observe a continuous stream of fuel or a steady flow of dropplets, there may be a problem with the vapor seperator. DO NOT attempt to open the vapor sep, you'll never get it back together correctly!<br /><br />Sorry for the long post, but the popcorn is usually caused by water in the fuel, or excessive fuel leaking into the crankcase. If you don't feel confident performing these tests, seek out a QUALIFIED tech. I actually know of a very competent shop near Miami (North Miami actually) - Billy's Outboard Service.<br /><br />Hope this helps.<br /><br />-John
