3.0 Mercruiser fuel system question (carbureted)

[87glastron]

Howdy.

Newb question here. My engine (1987 mercruiser 3.0 liter 130 hp in a glastron x-19) has been sputtering and loosing power. I am assuming it's a fuel related issue. (New to I/O engines but an old gear head) I am going to go through the fuel system, replace fuel filters, lines, fuel gauge sending unit, clean the carb etc. but as I was looking at it I have a question, see pics

There are 2 lines coming from the fuel pump into the carb. One metal and one a yelowish plastic. I have looked through my manual and have not found anything discussing this. What are the 2 lines for? Is one pump and one return? Help me out here.

Thanks!

 

[Bt Doctur]

Re: 3.0 Mercruiser fuel system question (carbureted)

the motor is OMC and I dont think the OMC riser will match Mercruiser exaust.
Anyhow, the marine mechanical fuel pumps have 3 fittings. fuel inlet, outlet to carb, and a "tell-tale" . this yellow line will show liquid when the diaphram has failed in the pump.it keeps you from blowing up .instead of fuel in the bilge it directs it directly into the carb.

 

[87glastron]

Re: 3.0 Mercruiser fuel system question (carbureted)

Thanks for the reply! So it's an OMC not a mercruiser engine? Nice. OK.

OK well as you can see in the bottom picture I have some fluid in the "tell tale" down near the pump where it's darker colored. Does that mean my pump is shot?

 

[kd7isf]

Re: 3.0 Mercruiser fuel system question (carbureted)

ANY fluid in the telltale line = bad

I would replace the fuel pump.

Hope this helps

 

[87glastron]

Re: 3.0 Mercruiser fuel system question (carbureted)

Thanks again for the replies, I will need to get the engine numbers to find the right fuel pump, and I am finding more and more to not like about this situation, I guess it is an OMC engine, but I have a mercruiser Alpha one outdrive. Boat has been taking on water even though all the boots and seals on the drive look good as does the hull. I am wondering now if this mis matched engine to outdrive could have something to do with the leak.

Thanks for the help guys.

 

[beads8]

Re: 3.0 Mercruiser fuel system question (carbureted)

Mercruiser always only applies to the drive. There can be several different engines that that supply the power. My "Mercruiser" is driven by a 3.0 liter Chevy engine, so your engine would not be considered a mis-match with the outdrive. Is the boat taking on water when it's just sitting in the water or does it seem like more is coming in while you are running it. I had a problem once where the clamps on the exhaust tube/pipe that goes from the exhaust riser coming off the manifold to the outdrive were loose and water would pour in while the engine was running. This tube expels both exhaust and water that has cooled the engine.

 

[nola mike]

Re: 3.0 Mercruiser fuel system question (carbureted)

As an aside, I'd like to see some pics of the boat, are we twins?

 

[87glastron]

Re: 3.0 Mercruiser fuel system question (carbureted)

We might be twins.

 

[87glastron]

Re: 3.0 Mercruiser fuel system question (carbureted)

Well, I replaced the fuel pump, tell line, fuel lines from the tank to the pump and pump to the carb. Cleaned the carb well with a spray in product (while running) and added a fuel system cleaner to a fresh tank of gas. (After completely emptying it while the pump was out.) Also replaced my fuel sending unit for good measure while I had it apart. Did this all Saturday morning before it hit 100 degrees here in KC. Took her out Saturday afternoon for a test run and it ran like a new boat. (Better than it's ever run for me.) Went out again Sunday and again ran wonderfully. Planes quicker, runs stronger and seems to pull a great deal harder. Oh and the gas gauge works too.

Thanks for the help everyone.