Hey guys. I have a 1990 Formula 242ss with a gen 6 502. I have had the boat for 3 or 4 years and I am going on my 4th fuel pump. 2 red Holley marine pumps and the last was a Mallory. What could be causing this? The Holleys I would be able to give a tap and get them working again time after time the Mallory worked great last year put boat away for the season fired it up for the first time last weekend, boat sat for the week decided to do a few things to it a week later and figured id see how it started and it ran for a minute and died. Fuel pump fuse is blown and if I send power to the pump it will not run. I am about to pull the trigger on the raw water/mechanical fuel pump set up but have heard bad things about it. Please any input would be greatly appreciated before I go down the wrong path. Do I need a suction pump? Its mounted as low as I can get it. Do the electric pumps need some kind of maintenance. I believe they are both pushers. Is there another pump that may suite my needs a bit better?

Just the same reason I started using Carter Competition Series Electric Fuel Pumps.

Cavitation is a killer.

Some fuel pumps still can't handle ethanol - believe it or not. Believe it !

Some deaded head fuel pumps don't like to be dead headed for long.

POS fuel pumps. Most electric Airtex in cars comes to mind. But they can't handle ethanol either. So they are really POS x 2.

Back in the day when Holley pumps where are only choice...they would seize here and there. Some would water them down (externally) to cool'm, others figured out to mix some Marvel Mystery oil or equivalent in the fuel to keep the pump lubricated. Thus why you still see some additives that promote themselves by saying 'lubricate the fuel system.' Shouldn't need those now a days as many good pump out there.

^^^^ correct on the cavitation part from SB, Also fuel pumps hate heat, restrictions - poor filtration, restricted voltage, excessive voltage, water any forms of it running thru them, and another killer is running them out of fuel.

Most OEM stock Merc, Mercruiser and Volvo use AirTex electric fuel pumps. I have seen some bad right out of the box - OEM Airtex.

Is the carter a suction pump? Had good luck with them? Cavitation caused by air in the line? What causes that? I was gonna smoke the fuel system to make sure airs not getting in anywhere.

It is best to do vacuum pressure tests and fuel pressure tests plus gas samples for any form of fuel contamination along with dumping and cutting open your fuel filters for inspection..

Next test is to use clear fuel line hose for testing purposes only and run the engine to see how the stream of fuel looks and flows - if any air bubbles in the fuel stream or lack of lack of a fuel stream is either a restriction or air entering. Also check your anti siphon valve at the fuel tank to make sure that is not causing a restriction.

Ok inspecting filter/fuel and air bubbles I understand. As far as vacuum testing and pressure testing goes im going to suck fuel right? Pinch the vent line? Any specific pressure or just suck it down and make sure it holds vacuum for a few minutes? Thanks

No with a Vacuum testing gauge and engine running. Merc specs is no more than 2 hg's pulling vacuum testing. The more vac (hg's) pulled the more restricted your fuel system can be. Possible anti siphon valve as well - also other things are too small of diameter pick up and or fittings and or fuel line or restriction of any .

fuel pressure testing is with a gauge also that will read fuel pressure in psi with engine running. .

Depending on your fuel system set up and fuel injectors, - Basically for mild to slightly medium moded engines to stock engines for the past x amount of years is 3 bar injectors with a matched fuel pressure regulator in which is 43.5 psi - for the fuel pressure of this system give or take a couple of psi as well if not right at 43 psi.

Again DEPENDING on set up and fuel requirements you should be within a certain spec for fuel pressure. What is your set up and fuel injection set up along with your fuel injectors ? Your engine are not OEM stock I know that much. Good luck

he is running holley reds so it is a carb setup. pull the pick up out of the tank. clean the little screen. gluck on it is a big restriction. as far as bravo raw pump with mech fuel pump there are so many out there running now it can't be a junk setup. if staying electric, keep a spare in the cuddy.

Is the pump wired with a relay to supply proper current and voltage to the pump? This can cause pumps to fail also.