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choprdoc

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"I have a 97 Johnson 40Hp, 2 c

"I have a 97 Johnson 40Hp, 2 cycle, model J40TTLEUC. The vro started messing up and was putting to much oil thru, fouling out plugs and not wanting to idle. My local mechanic recommended removing the vro and going to a regular fuel pump so I did. Now the motor runs great at idle and up to about 2/3 throttle but after running at wot for about 45 - 60 seconds, it starts surging. I do not think my mechanic has any ideas. so far we have replace fuel pump, filter, hoses, rebuilt carbs, timing Link And Sync, changed plugs all with no affect. When it starts surging, I can back off the throttle a little and it runs great. We have checked and it is not losing spark. What can we check now?"
 
"Fuel pump may be for smaller

"Fuel pump may be for smaller hp engine. Fuel hoses between pump and fuel supply may have too small an inside diameter (restriction). Fuel/air leak may exist between at some point between the pump and fuel supply.

If a built in tank, the anti siphon valve may be sticking (which would also have made the VRO pump more oil than fuel)......

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
"Have checked for any air/fuel

"Have checked for any air/fuel leaks and have found none. Tried another new fuel pump and it still does the surging. Bought a new fuel hose assembly, will try that today."
 
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