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Mercuriser 5.7 Electric Fuel Pump Issues
Ripple270
Member Posts: 18 ✭
New '02 Rinker 270 Fiesta Vee owner here. The engine is a Mercruiser 5.7 MAG MPI. I purchased the boat recently and have enjoyed it so far, although it needs some minor repairs, as expected for a 16 year old cruiser. The cool fuel pump was making a loud whining sound when purchased, but the boat started up fine, occasionally there was a hard start (I assume now that the pump was failing). The whining noise was always present even with the key in the off position. I'll assume now a faulty relay was to blame. When the pump died and the boat would not crank I started throwing parts at it. I began with a low pressure / booster pump on the starboard side of the engine thinking that may be the issue and an easy fix, next I replaced both fuel pump relays. Nothing different, same non crank issues that sounds like the engine is starving for fuel. I relieved the valve on the fuel rail in attempts to de-pressure the fuel system in case vapor lock was a possible culprit. No luck.
I feel like it is the high pressure pump itself at this point due to the process of elimination and the fact that the previously mentioned whining noise coming from the pump has stopped. Has anyone replaced this pump on this engine before? It is absolutely buried in the bottom of the bilge! I have seen some ideas of people suggesting to remove the engine to change it which sounds extreme. I wouldn't want to go that route unless it was absolutely necessary. I can see having to remove the header on that side of the motor to access, but even that sounds like a job for a professional marine mechanic. I have seen some nightmares removing rusted on marine headers before so I am weary of that as well. There is very little room to work around the black plastic box that houses the fuel pump assembly. The generator, gen batteries, and hot water heater are all in the way of where you would need to lay to access it. I'm thinking that you'd have to be small and limber to get to this pump assembly, as well as be able to remove a lot of hoses surrounding the housing. Are there any other possibilities or suspect parts that could be caused by this issue?
Any guidance or assistance is much appreciated! In the meantime, I'm going to order a new aftermarket cool fuel pump and get the multimeter out to test the resistance on the low pressure pump that I have already replaced.
I feel like it is the high pressure pump itself at this point due to the process of elimination and the fact that the previously mentioned whining noise coming from the pump has stopped. Has anyone replaced this pump on this engine before? It is absolutely buried in the bottom of the bilge! I have seen some ideas of people suggesting to remove the engine to change it which sounds extreme. I wouldn't want to go that route unless it was absolutely necessary. I can see having to remove the header on that side of the motor to access, but even that sounds like a job for a professional marine mechanic. I have seen some nightmares removing rusted on marine headers before so I am weary of that as well. There is very little room to work around the black plastic box that houses the fuel pump assembly. The generator, gen batteries, and hot water heater are all in the way of where you would need to lay to access it. I'm thinking that you'd have to be small and limber to get to this pump assembly, as well as be able to remove a lot of hoses surrounding the housing. Are there any other possibilities or suspect parts that could be caused by this issue?
Any guidance or assistance is much appreciated! In the meantime, I'm going to order a new aftermarket cool fuel pump and get the multimeter out to test the resistance on the low pressure pump that I have already replaced.
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