What's the difference between these fuel filters?

[jrampey]

Help,

I'm struggling with a fuel starvation problem with my Mercruiser 4.3L... As part of my spring maintenance I purchased a new fuel filter/water separator - Mercury part# 35-802893T. Took the boat out and would cut out above 3800 rpm. Changed filter to 35-802893Q01 (knew that the filter was the only variable) and ran great for 3 - 4 weeks. Then started cutting out randomly for a second or two. Thought it was a weak fuel pump so I replaced... turned out to be an ignition problem - bad crimp at the kill switch. During all of that I changed fuel filters again (trying to make sure dirty gas wasn't the problem) and this time back to the 35-802983T. Now will only rev to 4400 and wavers a bit - also if I punch it to WOT it will bog after 3 or 4 seconds... then catch and run (previously WOT was 4600). This feels like fuel starvation again.

Is the fuel pump system so close to capacity that a little difference to resistance in the fuel filter is too much to overcome?

 

[Bt Doctur]

Re: What's the difference between these fuel filters?

No, but a sticking anti-syphon will cause the same effect.

 

[jrampey]

Re: What's the difference between these fuel filters?

Yea, from what I've read here it's a possibility. The antisiphon valve is in the hose barb fitting on the top of the fuel tank right? I just read here that it's not required if the fuel lines and other components of the fuel system are above the fuel tank... any comments? I'm thinking I'll remove it and replace with a simple adapter, 1/2"MPT to 3/8" hose barb and see how it works. Any reason I shouldn't?

 

[cr2k]

Re: What's the difference between these fuel filters?

One is for carb engine and the other is finer filter for FI engines.

Could be your carb needs rebuilt.

 

[jrampey]

Re: What's the difference between these fuel filters?

Cr2K,

During all of my poking about I removed the carb top and checked for dirt, trash, water in the float bowl. I replaced the needle and seat and checked and adjusted the float level... there was no trash or water in the bowl - checked and cleaned the screen filter on the carb fuel inlet. Anything else you'd recommend?

 

[Don S]

Re: What's the difference between these fuel filters?

Have a look at this thread and do the tests. That will eliminate the boats fuel system, if all checks ok, check your fuel pump pressure while running. Just remember, if you can't get fuel to the pump, you won't have pressure. So check the boats fuel system first. Or hook up a remote tank and give it a try.

 

[sethjon]

Re: What's the difference between these fuel filters?

Its possible that the fuel pump isn't putting out enough. It takes a lot of pressure to get through the filter.

 

[Don S]

Re: What's the difference between these fuel filters?

Its possible that the fuel pump isn't putting out enough. It takes a lot of pressure to get through the filter.

It doesn't take any pressure for the gas to get through the filter, vacuum pull the fuel through the filter. The water seperating fuel filters are NEVER on the pressure side of the fuel pump.

 

[sethjon]

Re: What's the difference between these fuel filters?

Thanks for the correction.