95 Johnson - 90HP, RPM under 3800

[hinksj]

95 Johnson - Non-VRO, V4 Cross Flow - 90 hp<br /><br />Used bad gas last year, ran the engine dry (gas) for the winter ... at that time all was well.<br /><br />First time this year to operate, start and idle ok. Top end RPM is only 3800.<br /><br />Replaced spark plugs. Removed both carbs, dis-assembled (but did not extract fixed jets). Cleaned with carb-cleaner and used compressed air to dry and clean out all air-ways.<br /><br />Re-assembled this week-end. Starts and idles great!. Still max rpm is 3800. While running at WOT (3800 rpm), presses key in for primer choke ... rpm increased to 4500. That tells me I still have a fuel issue and most likely not an ignition issue.<br /><br />Dis-assembled the fuel pump, cleaned it, did not replace the diaphram or check values. Still at 3800 rpm at WOT. While at WOT I kept squeezing the gas primer bulb to test if fuel pump pressure was low ... no change in rpm.<br /><br />I installed a glass in-line fuel filter prior to the fuel pump. No air bubbles in fuel line.

 

[jimraelee]

Re: 95 Johnson - 90HP, RPM under 3800

Joe.... have you purged out all the old gas, Is there a high speed adj screw... that may be holding you back as well as fuel pres.. check that inline, as the engine is running. Your manual should have a specific range... im guessing about 5-10 psi. what about this primer key you talk about Im not familar but if you choke the engine with closing off air supply and get more rpm then it sounds like excess fuel. I would run at the max rpm you say you get for a 20 sec or so and imedatly shut off the engine and examine the plugs.. they may be loaded up with excess fuel... heavy black.<br />jim

 

[hinksj]

Re: 95 Johnson - 90HP, RPM under 3800

I drained all the old fuel and replaced it with new.<br /><br />The key chock I mentioned is the electric choke primer solenoid that by-passes the carb jets and directly dumps fuel into the throttle-body for cold starts.<br /><br />There are no hi-speed neddle jets ... all fixed jets.

 

[JB]

Re: 95 Johnson - 90HP, RPM under 3800

Hi, Joe.<br /><br />I suspect that you are not getting fuel to one or two cylinders at high speed. If those cylinders fire when you choke/prime that supports your original theory.<br /><br />It could be that not all cylinders are firing at any speed. Those V4s can start and idle beautifully on 2 or 3 cylinders.<br /><br />Kill each spark plug in turn at idle. If you have one or more that don't cause a drop in rpm, they are dead. Side by side dead ones are a carb problem; a dead bank is a powerpack problem.<br /><br />Squirt some fuel mix into each carb throat while at idle to see if fuel will bring back any dead cylinders.<br /><br />Let us know what you find.

 

[hinksj]

Re: 95 Johnson - 90HP, RPM under 3800

Thanks for the insight on a possible dead bank.<br /><br />When I removed the plugs, the two starboard side plugs where really bad compared to the port side. I will test out the ignition next week end.<br /><br />Thanks again for your comments.