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Posts: 1
Registered: ‎12-14-2020

1998 Evinrude 250 (CARB) running rough

Hey gents. Thought I'd see if anyone has had this issue: I have a 1998 v6 250 outboard, the carburated version. I got it from a liar who said "It runs just fine". Well, it starts well after I fixed the primer solenoid. But at low speeds, it runs like trash. I often troll at 2000 rpm, and it will intermittently run fine, and then run like a cylinder or two dropped out. It has new Champion plugs as prescribed by the manual. I ran it on a clear line directly from the tank and there no bubbles on the inlet side. However, after the pump, I noticed a large bubble that hung out right at the top of the VRO pump outlet. It would get pushed down every pulse, and sometimes get sucked in a little while I was running, but there always appeared to be a bubble there. 

 

I attached a fuel pressure gauge to the outlet and at low RPM (around 1000) it would jump to about 3.5psi just after the pulse and slowly bleed down to about 1.5psi just before a new pulse. The book says at that RPM the pressure should be 4psi. My gauge could be off, so maybe it's getting up to 4psi, but it's not styaing there. The book said nothing about the pressure bleeding down. Could this be the cause of my crappy performance? At higher RPM it seems better, but I know higher RPM mask all sorts of issues. When you give it throttle, it open up, but then the engine's tone changes. I thought it was the prop coming out of the water, but now I'm wondering if it's not just the engine going lean. At higher RPM, the pressure never seems to reach 5psi. 

 

I took apart the VRO and the diaphragms look abosolutely new. No tears or evident wear. Everything looks immaculate. Looks brand new. The one diaphragm is purple and the flapper is brown indicating OEM components. Could my issue be on the carb side? Are they just letting too much fuel in? Sometimes when I go to throttle up, it will bog down. You sort of have to jab a few times to get up in RPM. It's really weird. Is this a fuel issue, or could it be power pack? Only test I did for that is a voltage test. I'm getting a steady 13.26V at low RPM. Stator has been overheated at one point and there is some evidence of it melting/dripping down. Grounds are clean, batteries new and terminals secured with clean bolts and not corroded.