Odd fuel problem? 1987 40HP Evinrude

kaferhaus

Petty Officer 1st Class
Joined
Dec 17, 2008
Messages
250
Here's what it does. starts easy, idles great and accelerates to full throttle fairly quickly. once it gets to full throttle or sometimes just before it will "bog" then immediately pick up run fine for anywhere from a few seconds to a couple minutes and do it all over again. It also will occaisiionaly do this at maybe 3/4 throttle.

The oil side of the VRO was plugged off by a previous owner.

When would you look first, the fuel pump or carb floats? Or is this perhaps not a fuel system problem??

I can buy a new non VRO pump for 100 bucks... but the parts house tells me there's two types I can use.... one that mounts to the crankcase and gets it's vacuum from there and one that I'd run a hose to the existing port on the crankcase that feeds the installed VRO pump.

If I got the one that mounts to the crankcase... where would I mount it to get the vacuum? Is there a port somewhere that's got a screw in it or something??

This engine has power pack that's not 3 months old and new coils...

Obviously I'm no expert or I wouldn't be asking questions here... but it would seem logical to me that the fuel pump isn't keeping the carbs supplied with enough fuel..... but then again once it bogs it recovers within a second or two...

I haven't tried running it on the hose to see if it does the same thing without a "load" on it other than the prop.... but thought that might be a useless test?
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Odd fuel problem? 1987 40HP Evinrude

it mounts the the bosses the older style pumps mounted to. they are already their. you just plug the existing pulse line so it does not leak, and use the boss. should have a 1/8 inch plug in it now. 2 bolt holes each side.

fuel pump. http://www.iboats.com/Fuel_Pump_Sier...view_id.174141

gasket goes between block and pump.

this is a 2004 50 hp with convention fuel pump conversion:

200450hpJohnsonforsale005.jpg


here is a 93 40 same thing.
vrotofuelpump001-1.jpg
 

kaferhaus

Petty Officer 1st Class
Joined
Dec 17, 2008
Messages
250
Re: Odd fuel problem? 1987 40HP Evinrude

Thanks Tash, The fuel pump will be here Monday.

Since my original post I tested the current pump... it did not pass the vacuum test... tested the output (into a glass jar) and it was inconsistent.... which would explain the problem...... run good, stumble, run good...etc.

There likely was no reason for the previous owner to disable the VRO back whenever he originally did it.... I know some people hate them but I've never had a problem with a oil injected engine....

Now I gotta do something about water intrusion into the foot.... I've never been into the gear case on one but I guess I'm about to get an on the job education on replacing the seals...
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Odd fuel problem? 1987 40HP Evinrude

In english, what is kaferhaus?
 

kaferhaus

Petty Officer 1st Class
Joined
Dec 17, 2008
Messages
250
Re: Odd fuel problem? 1987 40HP Evinrude

Kafer = beetle haus = house

I used to collect old VWs.... thus the moniker.... I had a 40x60ft building full of them.... it was the "beetle house"
 
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