84 3.8 OMC Loads up

[hamiltonjb]

We have had this boat a short while. Runs good when it's cold but once warm it wants to load up and not idle. This 2 barrel Rochester has an extra tube from the fuel pump that drips gas into the top of the carburetor. It seems to be the cause of the problem as if I stop the drip ( stick my finger over the hole) it idles great. What the heck is it's purpose and can I get rid of it or is it a fuel pump problem? I have worked on cars since the 60's and quite a few Mercruisers and have never seen such an arrangement. Not too impressed with OMC so far.<br />Any advice would be greatly appreciated.

 

[Haut Medoc]

Re: 84 3.8 OMC Loads up

I'm pretty sure that means you have a ruptured diaphram, and need to replace the fuel pump.

 

[KaGee]

Re: 84 3.8 OMC Loads up

DO NOT GET RID OF THAT TUBE!!!<br /><br />That is the fuel pump drain tube. It should normally be dry. Fuel coming from that tube indicates that you have a fuel pump with a leaky bladder.<br /><br />Time to replace the fuel pump before proceeding with any other diagnosis. However, that well may be the problem here. That one is about $90 if you replace it yourself.

 

[hamiltonjb]

Re: 84 3.8 OMC Loads up

Thanks you guys, I'll check out the fuel pump. So that tube is some kind drain? Why would they drain it into the carb?

 

[vipzach]

Re: 84 3.8 OMC Loads up

It drains there because in a boat the fuel can't just drain out on the ground, like it can in a car. You don't want your boat filling up with gas....you know what can happen then Do not like the others said get rid of that hose!!!! Get the pump fixed/replaced. It is alot less expensive then a blown up boat.

 

[Haut Medoc]

Re: 84 3.8 OMC Loads up

It's better than going into your bilge & makes your motor run crappy so you'll have to investigate...

 

[hamiltonjb]

Re: 84 3.8 OMC Loads up

Thanks again,<br />I thought maybe it could drain back into the fuel tank. But I like the idea that it does give you a warning about the pump diaphram. Nothing like breaking down 75 miles down the lake, just about sundown with a storm blowing in with a whole boat full of women and kids. I'm also having trouble with the mechanism that raises the outdrive out of the water. It is a gear and motor arrangement that seems to be geared way too high. When it works it raises the outdrive in about a second. But most of the time I have to fool with it levering the switch over and over or getting in the water and lifting it by hand until it takes over. Is there a way of gearing it down? Or do I have some worn or out of alignment parts?

 

[vipzach]

Re: 84 3.8 OMC Loads up

You probly have something that is wearing out or going bad. I would start a new thread/question about your drive problem though, it will get more attention that way.

 

[KaGee]

Re: 84 3.8 OMC Loads up

If you plan on servicing this yourself, you need to get a service manual and become familiar with it's operation.<br /><br />Your tilt problem is common and is usually caused by poor electrical connections someplace. The fast raising is natural. The tilt is simply to raise the drive for trailering or docking. It is not used for trim. And never run your motor with the drive anyplace but all the way down. unless you want to tear up your ball gears.

 

[hamiltonjb]

Re: 84 3.8 OMC Loads up

Thanks, <br />Thats encouraging. Since the boat has always had that symptom I thought it was normal. I realize that the tilt is not for trim, I have a seperate trim and meter. I'm used to the hydraulic tilt on the mercs. They have their own problems but I think I like the merc design better.<br />Anyway I've ordered a service manual, fuel pump, fuel filter/water seperator and I'm pretty confident I can get it going.

 

[olbuddyjack]

Re: 84 3.8 OMC Loads up

I thought maybe it could drain back into the fuel tank.

I think I read here that theres a coast guard regulation prohibiting fuel return lines to the fuel tank. I dont know why but I'm sure theres a good reason.