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Hesitation/low power (lack of fuel psi)

Slow-roller

New member
Please help:

1992 carb’d 5.0 Mercruiser low power issue.

Replaced fuel hose (was hard and needed replaced anyway), fuel water separator and installed a clear inline fuel filter so I could have a visual. Boat starts, idles and runs fine until you get anywhere close to WOT and it hesitates intitially but then accelerates, although not nearly as well as it should. It struggles to get on plane when normally it would jump right up no problem. On the muffs in the driveway, the in-line fuel filter was completely full but when I took it to the lake, I saw that it was so empty I couldn’t believe it was even running. So I checked the usual suspects:

-removed vent hose on tank side and vent side and blew air brought it (no blockage)
-blew through actual vent (no blockage)
-removed pick up tube from tank expecting strainer to be clogged (no blockage and ball valve/check valve sliding freely)


Unfortunately, I don’t have a way to test inline fuel pressure post pump but is it safe to say the fuel pump is the culprit?
 
If that's a Q-Jet carb, look at the inlet filter in the body (where the hose/ line attaches). Mine loved to have brown crud build up in there with similar results.

Jeff
 
If that's a Q-Jet carb, look at the inlet filter in the body (where the hose/ line attaches). Mine loved to have brown crud build up in there with similar results.

Jeff


No dice. Great suggestion as I was unaware of there being a filter here. She’s a little dirty but definitely no restriction.
 
sounds like fuel pump is toast.....

On the in-line filter - its ok for test purposes but doubt its approved for use in a marine application.....so I'd remove it once the troubleshooting is over...
 
sounds like fuel pump is toast.....

On the in-line filter - its ok for test purposes but doubt its approved for use in a marine application.....so I'd remove it once the troubleshooting is over...

Thank you for the reminder. 🍻

I have standard automotive fuel hose currently installed also that I’ll be replacing with USCG hose. Just went with what was available at the time.
 
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