need opinions 1886 Johnson 90 V4

[jimbojonesmc]

What i have tried to fix problem. 2 new fuel tanks, all new fuel line from tank to carbs, new fuel line primer bulb, carbs rebuilt with
OEM kits, has new fuel pump (non VRO), new fuel filters, no kinks in fuel lines. No vacuum leaks,
PROBLEM
Will idle and start out running good. After a few min at WOT it will bog down to about half throttle.
If I push up on the electric key primmer rapidly it will slowly pick up to WOT. Stop pushing on electric key primer back to half throttle it goes. Pumping the fuel line primer bulb makes no difference. Removing
fuel tank cap makes no difference .

 

[racerone]

What does a compression test tell us here ?

 

[jimbojonesmc]

The compression is 110 lowest and 118 highest

 

[mstahl1171]

Are we sure the float valves on carbs adjusted correctly? Sure the primer selonoid is good? I had a similar problem with my 1988 V6 150. Turned out the primer selonoid gasket was bad. repair kit was 20 bucks.

 

[emdsapmgr]

You must mean that you have a 1986 model.. When you push in on the primer, that adds extra fuel: so when you do that and the engine picks up-that means the engine is running lean. Starving for fuel. So, it takes a minute or so before the engine consumes more fuel than the fuel system can provide and the engine slows to half speed. A fuel delivery problem. The bowls are running out of fuel. You have addressed the normal (correct) steps for a fuel delivery issue. Maybe a couple of questions: what part number was the old-style fuel pump you are running? Are the carbs the original factory carbs? Did you visually inspect the mid and high speed jets and compare them with the original factory parts list jet sizes? Floats set to correct height? Running OMC fuel line of at least 5/16" size? Did you replace any fuel lines under the cowl? Were any of them bulk hose, or were they original factory hoses-makes a difference.