Outboard Woes

[Claude A. Moreau]

I bought a couple of 1987 Merc outboards a year and a half ago and they are just about driving me crazy. Unfortunatley. I bought them sight unseen, having been told that "they run great and are in good condition" <br /> <br />I had the carbs overhauled, the fuel pumps rebuilt, new impellers...etc. before installing them. They have never run properly, but I manage to use them anyway,and have put a few hundred hours on them.<br /><br />Every time I use them the same two problems occur. They run reasonably well for two or three hours, then all of a sudden,both motors go into some resembling a "limp home" mode. The port side motor will run, as long as I don't rev over 2800 rpms, and the other one doesn't rev over 2200 rpms. If I give even a tiny bit more throttle to either motor, it will quickly stall out. They will rev up and peg out in neutral, but not under a load. Usually this problem will eventually go away later in the day, but not always.<br /><br />The other serious problem is that at some point after the above problem occurs, The starboard motor always will die out. I can easily start it up again, but it will only run as long as I keep pushing in the key button (choke?). <br />this problem used to go away after a while, but now I have to do it all the way home every time. This is a major pain in the ***.<br /><br />I have figured out that my main problem has to do with a dissruption in the fuel flow to the motors. I have eliminated all sources of fuel supply problems outside of the motors, and am conviced that the problems are occuring internally. I had the carbs checks out professionally, and they apparently are not the problem. A mechanic suggested that water may be getting through the engine cowling and getting into the carbs (our waters are usually pretty choppy), but I am not convinced that is so. <br /> I am unable to talk any local mechanics into going, out with me to diagnose the problems, so I am appealing to you guys for any ideas.<br />Mahalo (thanks)

 

[Coolmaker]

Re: Outboard Woes

How far away from the motors is the tank? What size lines are feeding the motors? Is the fuel tank vent okay? Have you thought about a "booster pump to feed them? There are many things that go on in a fuel system. The fact that they run good for awhile and then not so good leads one back to fuel. What temp are the motors running?

 

[Laddies]

Re: Outboard Woes

It sounds like you have a built in tank and the anti syphon valve on the tank outlet or a problem with the pick up tube in the tank

 

[Claude A. Moreau]

Re: Outboard Woes

I have tried switching fuel sources while the problems occur and no relief from problem. I tried it yesterday with a portable six gallon tank with a short hose to motor and same situation. I really think the problem is in the motor somewhere, but am stumped. By the way, the motors are 70 hp. Thanks for your offer to help.

 

[Claude A. Moreau]

Re: Outboard Woes

I have tried switching fuel sources while the problems occur and no relief from problem. I tried it yesterday with a portable six gallon tank with a short hose to motor and same situation. I really think the problem is in the motor somewhere, but am stumped. By the way, the motors are 70 hp. Thanks for your offer to help.

 

[wilde1j]

Re: Outboard Woes

Have you checked fuel pump output pressure? Do your motors have tubular fuel filters? If so, when were they last changed?

 

[Claude A. Moreau]

Re: Outboard Woes

Aloha Jim. Both motors have clear glass tubular fuel filters. I don't know when they were changed, but I can see no rubbish inside. How can I check the fuel filter output pressure? Why would the motors run o.k. every time for 2 or 3 hours if there were problems with the filters and fuel pumps? Wouldn't the problems occur right away? This is a real brain buster!<br /><br />Claudezzzzzzzzzzzzzz

 

[pies]

Re: Outboard Woes

i am no expert by any mans, but this sounds like an ignition problem. when the engines start with the problem , i would be checking for spark at the cylinders. it sounds like after the engines are heated up good that something in the ignition system is breaking down.

 

[Claude A. Moreau]

Re: Outboard Woes

Aloha Pies. Sounds reasonable. How would I go about checking it out while bouncing around in the water? I have been unable to convince any local mechanics to to out on the water with me so far.<br /><br />Claudezzzzzzzzzzz

 

[ronmold]

Re: Outboard Woes

get some freeze-mist spray from radio shack ,used to find defective elec. components or a can of dust-off spray held upside-down. when the motors fail spray the switchboxes to cool them off. If problem clears up replace the switchboxes.

 

[Claude A. Moreau]

Re: Outboard Woes

That sounds pretty cool (pardon the pun). I'll try it! Any other ideas will definately be appreciated. Mahalo (thanks)<br /><br />Claudezzzzzzzzzzzzzzz