Strange Can of Worms

[four winns 214]

Getting ready to make a long trip in a 1984 Sea Ray cuddy with a buddy. We decided to replace the fuel pump on the boat's Mercruiser 228R based on its age. Bought an OEM pump from local dealer and installed it without a hitch, that is until we started the engine.

The engine started, but ran poorly. Then we noticed fuel leaking profusely from the Rochester Quadrajet carburetor. This engine has always run exceptionly well and has zero history of fuel leaking from the carburetor in the four years I've owned it. I can't help but think there's a correlation. The carburetor is now being rebuilt by the local guru of such matters.

I'm anxiously awaiting the opinion of the rebuilder (he wasn't in the shop when it was dropped off). Any ideas about this?

 

[cr2k]

Re: Strange Can of Worms

Pressure spring in the fuel pump may be faulty causing over pressure.
See if you can get a pressure reading on the fuel line at the carb connection.

Add a pressure regulator if necessary or return pump for replacement if bad.

 

[wire2]

Re: Strange Can of Worms

Where exactly is the fuel coming out?

 

[erikgreen]

Re: Strange Can of Worms

Might be the carb itself. Qjets have a history of leaking from some of the factory plugs after a while, it's a design flaw.

Figure out exactly where the leak is coming from... might be that the new pump has upped fuel pressure (good) and now you have a leak where you didn't before in a faulty joint in the fuel line.

Erik

 

[four winns 214]

Re: Strange Can of Worms

The carb is at the shop of a local boat mechanic legend with decades of experience. We'll know soon. I'm on a work trip right now and will be reinstalling the carb on Friday (assuming the carb rebuild goes as planned).

 

[four winns 214]

Re: Strange Can of Worms

Put the carb on after rebuild and started engine. Same leakage. Appears to be coming from an overflow port and the accelerator pump plunger.

Called Mercruiser. After describing the issue to the phone rep, he immediately indicated that he was familiar with the issue. It seems that vendors to supply mechanical fuel pumps are getting scarce. And the pumps they supply do produce too much fuel pressure in some applications, my 228R 5.0L being one of them. The fix he said was to use the gasket for the 3.0L engine that is thicker. If that doesn't work, use two of them. This reduces the throw of the pump lever.

NOBODY in the local boat maintenance community has ever heard of or experienced this issue. Hopefully this information will help somebody.

 

[Hansolo99]

Re: Strange Can of Worms

Let us know the outcome............

 

[dubs283]

Re: Strange Can of Worms

i have run into this problem and yes the solution is to install a thicker gasket

the gasket is actually quite thick, about 3/16"

 

[buzzm19]

Re: Strange Can of Worms

I ran into a similar problem with my nova with twin 260's. Both fuel pumps of the original fuel pumps were only putting out 3lbs, spec calls for 5-7lb. I ordered two new pumps(not reman) installed them and had zero lbs cranking and no fuel at all, I have been a mechanic for a long time so first I took them apart and the two valves were fine, checked the plunger arm and found that the new pumps had twice the movement than the old ones. I knew it was the pumps because I before hand installed a automotive pump and instantly had 5lbs cranking so I knew there was nothing wrong with the motors. I changed over the old top of the pumps to the new ones and had 5 1/2 one and 6 1/2 on the other. I would say if you don't have at least some movement in the arm its probably activating too soon creating too much pressure, as you said about putting extra gaskets you are moving the pump arm away from the engine push bar giving it some play just as I explained. I know rochester carbs will take up to 10lbs before pushing the needle off its seat so if its flooding out I would guess you have too much pressure, a sure way to tell is a pressure gauge on the outlet from the carb. hope this helps Buz

 

[jeffnick]

Re: Strange Can of Worms

Why not just a pressure regulator between the pump and carb?

 

[nola mike]

Re: Strange Can of Worms

Put the carb on after rebuild and started engine. Same leakage. Appears to be coming from an overflow port and the accelerator pump plunger.

Called Mercruiser. After describing the issue to the phone rep, he immediately indicated that he was familiar with the issue. It seems that vendors to supply mechanical fuel pumps are getting scarce. And the pumps they supply do produce too much fuel pressure in some applications, my 228R 5.0L being one of them. The fix he said was to use the gasket for the 3.0L engine that is thicker. If that doesn't work, use two of them. This reduces the throw of the pump lever.

NOBODY in the local boat maintenance community has ever heard of or experienced this issue. Hopefully this information will help somebody.

there was a recent post about this with a similar problem, similar solution, if that helps.

 

[dubs283]

Re: Strange Can of Worms

Why not just a pressure regulator between the pump and carb?

too much extra stuff to add, you would need to route the excess fuel somehwere

on efi models, it goes back into the fuel/water separator or the VST depending on which model

 

[four winns 214]

Re: Strange Can of Worms

The thick gasket did the trick. It is MUCH thicker than the part number gasket specified by the manual. The thick gasket is cork sandwiched between thin pieces of composite gasket material.

The Mercruiser part number for the thin gasket specified by the parts manual for my engine is 27-41812. The Mercruiser part number for the thick gasket that actually works is 27-43186.

Also, the thick gasket was not available at my local Sea Ray dealer where I bought the first gasket. The shop where I obtained the thick gasket said that they WERE aware of the issue and lamented the fact that the information about the thick gasket is not included in the parts manual because it's pretty much a sure bet that the pump will cause over pressure problems with some engines. So there WAS somebody in the local maintenance community that was familiar with the issue.