I guess you don't know until you try. Install a new hunk of line and a disc filter. Why are these spec'd out like that? It likely has to do with the amount of head -tank above the carb. It can also alleviate issues when people use this rider on slopes. Know that these carbs have differences between the gravity feed and the pump feed. It may function correctly though. Another possibility is that the fuel pump itself is allowing fuel to enter the engine due to a rupture in the diaphragm. So, if you can't see the carb overflow- that could be the issue.

Another possibility is that the shutoff valve you installed is not sealing completely and if that is the case............the fuel system is essentially not equipped with a shutoff valve at all.
If you installed the shutoff valve correctly (placed between the tank and the fuel filter), there is little chance that fuel could be leaking through a defective fuel pump to gain entry to the crankcase through the pulse vac hose.
My experience with pulse vac fuel pumps is that if one is defective and allowing any fuel to enter the crankcase via the pulse vac hose, you will never observe the crankcase oil level on the stick to increase...........provided you turned off the fuel shutoff valve when you parked the machine.
Trace amounts of gasoline that enter an engine while the engine is operating WILL NOT accumulate in the crankcase to raise the lube oil level...........because the volatile gasoline will boil off immediately and the "gas fumes" will be whisked out through the crankcase breather to be burned in the combustion chamber.
So, the questions I ask are:
Do you still see the lube oil level increase (as measured on the stick)?
Do you see white or bluish white smoke out the exhaust when the engine warms up?
As Tom points out, the pump being in place is likely to maintain adequate fuel flow to the carb to compensate for variances in the elevation of fuel level under different angle situations during operation.

Might be helpful to know WHICH 18.5 we are talking about. There is more than one, model number.

Walt Conner

Thanks guys.....turns out it wouldn't run without the fuel pump hooked up....kinda strange.....figured gravity would be enough on level ground...but as you said....some carbs are tricky.

I think I know the issue now....I took a shortcut and installed a new float and needle valve but did not replace the seat.....obviously the needle valve isn't sealing off....I'll go back and do that and see how it does with a new seat.

This is a 2003---31Q777 model according to the local briggs shop. The numbers were pretty faint but I think that's right.

I doubt this is a factor, but this is the same engine that's giving me fits around getting the compression to release. I've adjusted the valves 9 ways from Sunday.....no help.....

If it makes it past the compression stroke...it cranks....but still kicks back sometimes....once it cranks...it runs fine. Flywheel key is good....

I'm stumped.

Thanks for all ur help fellas.....I see ur celebrating your holiday weekend meandering thru the boards! grin

Engines with a fuel pump use a different fuel filter than gravity fed engines.
Pump engines use the "white" filter @ 75 micron.
Non pump engines use the "red" filter @ 150 micron.

Bill has a point.

I have info on valve adjustment and compression release test that may be of interest to you IF you like. Address below, put in proper format and remind me, model number and what you want.

Walt Conner
wconner5 at frontier dot com

to Mownie: yes...definitely raised the oil level......and definitely a lot of whitish smoke that only appears when gas has gotten into the oil

when I change it.....the gas runs out last....Ive changed it 3-4 times since Ive been fooling with it....

Walt---I'll send you a note at your email for the instructions re: the valves

thanks much guys

***"replaced needle and seat but its still happening.....even tho I have a fuel shutoff installed"***

OK, I refer to the last sentence in the post above: "even tho I have a fuel shutoff installed".
In that statement, are you saying that you actually installed an inline, manually operated.........fuel shutoff valve? Or are you saying that the carburetor HAS a fuel shutoff valve already incorporated into it?

If you mean that you installed an "inline fuel shutoff valve", and the crankcase continues to be filling with gasoline.............then you are either NOT shutting off the valve.............or the valve itself is defective..............or (least likely) you installed the valve between the pump and the carb, and a defective pump is leaking gas into the crankcase.
Proper placement of an inline shutoff valve is somewhere between the fuel tank and the fuel filter (this placement also allows for easier replacement of fuel filter in the future).

Now, if you meant that the carburetor already has a fuel shutoff valve in it.......................you have fallen into the trap of thinking the device is a "total fuel shutoff valve" along with many other people.
The fuel solenoid valve (on carburetors so equipped) DOES NOT shut off all fuel. It only shuts off fuel to the MAIN JET, the pilot or idle jet can still pass a very small volume of fuel............and this small volume of fuel flow will still "drown" an engine crankcase in fuel while the machine is not running....if there is a defect in the needle and seat components.

The fuel solenoid is actually called an "anti-afterfire" solenoid valve and its sole purpose is to minimize the occurrence loud backfire bang out the exhaust when shutting down the engine.

Mownie,

I placed the fuel shutoff is between the filter and the carb.....(yeah I wasn't thinking....shoulda placed it before the filter) I think its ok because the engine will eventually starve for fuel and die when I leave it in the "off" position.

The carb does have the solenoid underneath.....and its working ok....Ive pulled it and checked to make sure the plunger retracts and extends when the ignition key is turned on and off.

I'm a bit confused on whether the pump can be allowing gas into the crankcase....but since this is an "above carb" tank...I guess maybe it can? Your earlier post above seemed to discount that possibility?

I still think not replacing the needle seat when I replaced the float and needle valve might be my issue--I'll pull the carb and replace that tomorrow.

Well Joe, I'm not "entirely ruling out the possibility" that a defective fuel pump could be a cause, just that it is a least likely suspect.
You should relocate the inline valve so it is placed between the tank and the fuel filter. Having it there makes it much easier to swap a fuel filter as you don't need to resort to pinching off the hose with vise grips or spilling fuel when you pull the hose off the filter.
The correct sequence of components should be: Tank - shutoff valve - filter - pump - carb.

Wondering how you did. In your application, I would think the pump could be allowing fuel leaking into the sump -seeing as though the tank is above.

I have the exac same engine in my Cub Cadet 1000 series and I had to replace the engine after 3 years as I did not watch the oil level well enough and the light did not go on to warn me that it was low. Anyway, my replacement engine has been ok except for a compression ring replacment and it stalling due to stuff in the gas tank that I had to get out.

well.....I made it someone elses issue....never could get it to stop filling the crankcase with gas.....it was either the fuel pump or something else in the carb

Finally got tired of spending money and time on it

Greatlakes16 - Best go back and re-read yer manual... that oil light on yer dash has to do with low oil PRESSURE, not low oil level.
Get in the habit of pulling the dipstick, wiping it off with a clean rag and re-dipping to get a good crankcase oil LEVEL reading EACH time BEFORE you start that engine to use it for any purpose.
And - if you should happen to smell gasoline coming from the oil on the stick....Stop everything, drain/replace crankcase oil/filter and fix cause of raw fuel getting into crankcase (usually thru carb or fuel pump).Crankcase oil diluted with raw fuel loses it's lubricating abilities and will soon get you a trashed engine. Also give serious consideration to adding a manual fuel inline shutoff valve - available from any L&G eqpt dealer.