Truck fuel pump

I have a friend who has a 74

I have a friend who has a 74 165 Mercruiser I/O and had a fuel pump failure. He installed a truck pump and he is having trouble running wide open for any length of time. In addition to being unsafe (I told him this) does an automotive pump not have the capacity to power a boat at full throttle?

"Jeff, the pressures should be

"Jeff, the pressures should be the same between the pumps, between 4-6psi. Have him ck the pressure after the pump. Although you are correct regarding the unsafe conditions of using automotive parts in marine applications. The fuel pump on a marine engine has a fitting on it with a hose that goes to the carb. It is there in case the fuel pump ruptures, the fuel will be diverted to the carb. An automotive pump does not have this, and if it ruptures, fuel will leak into the bilge and create a serious fire problem. Have him put a marine pump back on it please.......Daren

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"Check the fuel filters-the on

"Check the fuel filters-the one in the carb and the water separating filter. They will also cause fuel starvation.
Tom"

" I had a sticky check valve i

" I had a sticky check valve in a fitting coming off my fuel tank that caused a remarkably similar problem. It was in hose barb and I didn't find it until I ran the boat with the fuel line stuck in a portable gas can. In the meantime I had replaced every fuel filter and overhauled my fuel pump. I guess I started at the wrong end. Anyhow, perhaps your friend should try running the boat from a different fuel source. Disconnect the fuel line at the gas tank and submerge it in a can of fuel.(I did this in my driveway) If the boat works OK then its not a line, pump or filter problem..its a tank valve problem. The valve cost 75 cents but caused me hours of aggravation. He does need to go back to a marine rated pump real soon..... "