Correct diagnosis? Lack of fuel...

Hey everyone, newbie here. I started following this forum a few weeks ago after inheriting a project..... My father in law was given a 1999 sea ray with a mercruiser 3.0 I/O. Boat had been sitting for about 6 months. I picked it up for him and told him I would make sure it was running and do any additional maintenance (worked on cars a lot, not on boats, bigger difference than I thought). Anyway, down to the issue, the ignition works fine, starter turns the engine over but it will not start. No starting then dying, nothing. Tried opening the throttle out of gear etc. So I started poking around and found that there wasn't the slightest hint of gas smell in the carb. In fact taking the fuel line off found it to be completely dry. So I checked out the fuel pump on the side of the engine ( mechanical pump! New one on me ). The bowl had gas. I pulled the fuel line coming from the tank into the pump and hooked my brake bleeder up to it to put negative pressure on the line. Gas flowed easily so I guess the antisiphone valve is fine. The only thing I can suppose is the pump is bad. If gas is flowing freely to the pump and past the pump is not getting fuel am I correct to suppose the fuel pump? The pump seems easy enough to replace. With my lack of marine engine experience I just wanted to air this question out to see if I was thinking clearly. I would like to get this problem wrapped up for my father in-law. He was kind enough say we could use the boat when we wanted so putting a few hours and bucks into this boat is the least I can do.

Re: Correct diagnosis? Lack of fuel...

cheap and easy way to test fuel pump output is to disconnect the fuel line at the carb and crank the engine, grounding the coil wire of course - place the fuel line end in a container to collect fuel if it is pumping (may want to have a helper crank the engine for you)

have you checked the filter in the carb?? fuel pump filter??

also a good idea to verify spark at the coil tower

Re: Correct diagnosis? Lack of fuel...

Sounds like you accidentally found a problem. 6 months shoulnd't take out a fuel pump. There is filter in the pump itself. Take off the safety wired bracket off & look at it. Easy to get at.

Re: Correct diagnosis? Lack of fuel...

Like Dubs 283 said, best way is to verify fuel after the pump. If not you can always draw fuel from a container on the inlet to verify pump operation. If no fuel again, probably a faulty pump. Worst case scenario would be worn lobe but highly doubtful unless extremely abused and not maintained.

Re: Correct diagnosis? Lack of fuel...

change the filter first. the vacuum pump may have been able to pull fuel through the filter but the pump may not. Check the gas also if it was ethanol gas and sat for six months you may have some serious sludge and seperation in the tank, water too.

My suggestion is to change all the fuel lines and filters, drain and inspect the tank clean out if necessary. Put new gas in and try to start the engine. Make sure you check the float bowl in the carb for crappy gas too.

Those mechanical pumps are durrable units and don't go bad all that often.

Try ether, will the engine fire on ether? you could have an ignition problem also...

Re: Correct diagnosis? Lack of fuel...

Check the gas also if it was ethanol gas and sat for six months you may have some serious sludge and seperation in the tank, water too.

My suggestion is to change all the fuel lines and filters, drain and inspect the tank clean out if necessary.

Click to expand...

For 6 month old gas??? 2-3 years maybe replace the gas, but not 6 months. Why would all the lines need replaced?
The tank may have (doubtful) some water in it from some separation or other reasons, but even ethanol doesn't go that bad in only 5 months. If there is some water in the tank, it can be removed without emptying the tank.

Tyler, Replace the fuel pump filter, then disconnect the line going to the carb put a hose on the end of the line and and put the other end of the hose in a container and crank the engine over and see if it pumps gas.
Here is a link to download the OEM service manual for the engine. http://www.4shared.com/document/xEKlzP-s/Service_Manual_26.html

Re: Correct diagnosis? Lack of fuel...

Wow. Thanks guys for all the help. Let me clear up a few things I may not have been precise about in my first post.

1) Honestly we don't know how long the boat has really been sitting. It hasn't been in use for years because the family bought a new boat and were trying to sell this one. I am getting the six months from the fact that they said a potential buyer took it out around 6 months ago and it "ran".

2) I pulled the bowl off the pump. The gas in it seemed ok but one thing that was really odd is that the paint on the inside of the bowl had bubbled up (any ideas on that?) My next step I think is to get a new filter and completely drain the gas tank because who knows how old the fuel is.

3) I am certain that there was no gas getting to the carb. I disconnected the fuel line to the carb and tried cranking for a little while with out any fuel flow.

There may be other problems to deal with but but I think I may tackle getting fuel to the carb first and if that doesn't fix things I will start round 2.

Thank you guys for all the help and suggestions. Hopefully I can get this straightened out. I am going to start looking for fuel pumps tomorrow and I will keep you posted on the efforts.

Thanks again.