Motor Question...please help!
whynot
Posted 10/5/2007 1:12 PM (#278267)
Subject: Motor Question...please help!




Posts: 897


I am wondering if anyone can tell me where the fuel pump is located on a 1991 Johnson 40hp outboard. I have the manual that came with the motor as well as a repair manual and neither has a diagram that shows me where it is. I am pretty inexperienced with motors, but I don't want to pay someone $150 to put it in when it seems pretty easy to replace as described in the repair manual.

I have the replacement pump already, but I can't see anything on the motor that looks like it.

Thanks,

Chris

Mark H.
Posted 10/5/2007 2:42 PM (#278282 - in reply to #278267)
Subject: Re: Motor Question...please help!




Posts: 1936


Location: Eau Claire, WI
Not knowing that specific motor I am going to make several assumptions.

1. You're motor is carburated.

2. #1 being correct follow the fuel line backwards from the carb(s) to what will most likely be a fuel filter (possibly a small in-line unit on that motor) then back to what is most likely the fuel pump.

3. It will be one of two styles ( my luck there's a third ) Style one could be electronic pump (will be obvious by wires coming out of it) or style two would most likely be a diaphram-style pump. Might be as simple as removing the cover, cleaning the screen/filter and replacing the diaphram.

4. If none of this works...call your local OMC dealer give them the model and serial number of your motor and ask them what style.

Final thought ?

Not sure why you are asking this question but I suspect some people might point to fuel pump in an older motor like that when in fact if your motor is starving for fuel (getting some but not enough) that you could have a faulty pressure-bulb in your fuel line or a faulty fuel line itself. As gas line gets old, it gets hard and brittle, and developes cracks around the fittings and on sharp bends. The can be enough for the motor to suck air through that line and not keep enough line pressure for the motor to run properly.

Make sure you have diagnosed the correct defective part.

Hope this helped some.
Shep
Posted 10/5/2007 3:55 PM (#278293 - in reply to #278282)
Subject: Re: Motor Question...please help!





Posts: 5874


Good advice Mark.
whynot
Posted 10/17/2007 12:08 AM (#279888 - in reply to #278267)
Subject: RE: Motor Question...please help!




Posts: 897


I appreciate the advice. Sorry I didn't get back to this sooner(didn't know where it had moved to), for my sake and for the sake of my boat. The reason I was asking this question is that I was having problems with my motor that seemed gas related.

Basically, while motoring at full speed at the end of a long day of fishing the motor suddenly bogged down - it felt like I had hit a log or something. A mechanic suggest I try replacing the fuel filter first, which I did, but the problem persisted.

The next idea was to replace the fuel pump. Well, what I didn't know was that the fuel pump was part of the VRO pump on the motor, which is why I couldn't find it. After talking to a mechanic again, he showed me how to circumvent the VRO pump by installing a fuel pump, disconnecting the VRO pump, and mixing the oil with the gas in the gas tank.

So I did this, but I wasn't able to physically remove the VRO pump from the motor. I disconnected the power and the fuel lines, but there was still a line going from the VRO pump to the bottom of the motor, as well the oil line going to the VRO pump.

Again, I took the boat out and the problem was somewhat corrected. At times the motor would cut out/lose power at high speeds, but at others it would run fine. After explaining this to another guy, it was suggested to me the problem may have been a faulty bulb so I replaced that.

Well, I brought it out to the lake and now a whole new problem has arisen. Now when I start the motor I have to continuously choke it to keep it running. I can't put it in gear or it will cut out. Also, there seems to be some white stuff coming out of the motor that I've never seen before.

Any ideas? I am assuming the problem now has something to do with my amateur repairs, but would like to at least try again before bringing it in to a mechanic.

Thanks much,

Chris
Jimfish
Posted 10/17/2007 7:34 AM (#279909 - in reply to #279888)
Subject: RE: Motor Question...please help!





Posts: 106


Location: Des Plaines, IL
Sounds like a problem I had a couple years ago, and it was the oddest thing. Turned out it was when I had left the gas can in the boat for a couple of weeks, that gas had gotten "funky" and would run good when the motor was cool and the weather mild, but after the sun came out or the motor was running for a while it would act up. So Now I keep my gas and gas line in the garage.
I would make sure you get some fresh gas & oil before seeing the mechanic.
my 2 cents