2002 Mercruiser 3.0L Fuel Supply Problem *FIXED*

[POHRacing]

New to the forum, but not new to boats, and certainly not new to engine repairs... However this one has got me stumped!

I just picked up a 2002 Sea Ray 182 last weekend with a Merc 3.0L that only has 31 hours on it. It's been sitting for about a year since it has run properly, so I started by removing the fuel tank and cleaning it out the best I could (it had about 2 gallons of skunky fuel in it). After reinstalling the tank, putting in 5 fresh gallons of fuel, and replacing the dead batteries, we tried to crank her over. She cranked fine, but didn't start... no fuel was being supplied to the carb. I removed the fuel to carb line (at the carb) to see if fuel was getting to the carb, but after about 20 seconds of cranking we still had no fuel. I checked the anti-syphon valve, but it looks like the previous owner removed it altogether (I'll replace it after troubleshooting). At this point (just for kicks really), we added about 10 ounces of fuel directly to the carb, cranked it, and she fired right up. Thinking that maybe the fuel line being bone dry was hindering the pump from operating properly, we tried priming the fuel line by just pouring fuel directly down the fuel supply line... 20 more seconds of cranking and still nothing. So we bought a new pump... The new pump was identical to the old one in all ways except for the orientation of the fuel inlet. The inlet was 180 degrees off from the old one, and we couldn't install it without the inlet barb hitting the starboard side motor mount. So we disassembled the new pump, and oriented the inlet side 180 degrees the other way. When we were done, it looked exactly like the old factory pump. We went through the same procedures listed above, but we still can't get fuel to the carb!

What could I be missing here? I tried to bench-check the old pump and it seems to have suction and pressure... I'm assuming the new one does too.

I'm going to start by rechecking the 3.8" fuel line for pinhole leaks, but any input on how to troubleshoot this will be appreciated.

Thanks again,
Brian

 

[Don S]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

All it will take is an air leak in the fuel line between the tank and the fuel pump and the pump will not pull fuel. Could even be the fuel tank pickup if it's cracked or leaking air above the fuel level.
Short of pulling the pickup out of the tank and plugging the end, and hooking up a vacuum pump on the hose that hooks to the pump, I don't know how you would check it.

 

[POHRacing]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Thanks for the fast response, Don S. I figured since the pump only operates at around 6-8 psi, it will only take a small hole in the supply side for the pump to not operate properly. The other test I forgot to mention was that I hooked up a small mechanically operated syphon to the end of the fuel line where it would normally connect to the carb. I was able to get fuel to flow out of the tank, through the rubber line, straight through the pump, and to my syphon with no problem. Basically the same principle as sucking on the end of the fuel line with everything hooked up. It drew fuel quickly, and I can't imagine it took any more than the 6-8 psi mentioned earlier.

Should the pump allow fuel to flow through it unimpeded like that?

 

[Don S]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Should the pump allow fuel to flow through it unimpeded like that?

Have no idea, never tried.

 

[fishrdan]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

I was able to get fuel to flow out of the tank, through the rubber line, straight through the pump, and to my syphon with no problem.

Should the pump allow fuel to flow through it unimpeded like that?

That doesn't sound right as the valves in the pump should stop the fuel from "free flowing" through the pump. You mentioned that you had to take the base off the pump to get the fittings clocked correctly, did everything get put back together correctly, gaskets in the proper position?

 

[POHRacing]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

did everything get put back together correctly, gaskets in the proper position?

I'm honestly not so sure now... I did take apart the factory pump (which has never been torn down before) to make sure that I assembled the new one the same way though. While doing so I noticed that the valving in the pumps is slightly different. They're situated the same way now that I re-clocked the pump, but the valves themselves have a different (maybe just updated) design. The only thing I could have screwed up in the reassembly is the lower gasket. Theoretically there are only 2 ways to install it, since the bottom half of the pump is only fastened by two allen bolts. I made sure to install the gasket with the same side up as when I took it apart, but it could be off by 180 degrees I suppose.

 

[POHRacing]

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Re: 2002 Mercruiser 3.0L Fuel Supply Problem

Update... FIXED!

So we pulled the new pump off and did a visual inspection of the valves, seals, and location of the input and output ports. We compared the ports to the old pump, and sure enough the body of the lower fuel pump housing was clocked 180 degrees off from the ports of the old pump. Basically the new pump was constructed in a different mold altogether, rendering it useless the way we had set it up. We reconstructed the new pump using the old lower housing, clocked it the same way as the old pump, and bench tested it. After we reinstalled it, we installed clear 3/8" hose between the tank and fuel pump (for troubleshooting purposes only). It barely took one rotation of the motor for fuel to be seen moving through the inspection hose, and the motor subsequently fired almost immediately. We left the motor running for a couple minutes just to be sure there were no air bubbles visibly migrating through the clear inspection tube, but everything checked out fine. We installed a brand new 3/8" fuel hose for good measure, changed the oil and filter, and we're all set to get out on the water tomorrow morning!

Thanks for the input, guys... I can already see that I'm going to enjoy my time on this forum.

-Brian