Suitable fuel pump for 4.3LX Mercruiser

Hi Guys,

I have a 1988 Mercruiser 4.3LX that is having a fuel delivery issue. I'm almost certain the fuel pump is failing (I have removed the positive side fuel line and seen it cough and spit with a clean intake line. The fuel pump is just a generic auto parts one that was installed over a decade ago and has worked well for some time. With it showing signs of failure I wondered what a suitable replacement would be, or what specifications I'm looking for.

Anybody have any idea what fuel pressure the rochester quadrajet carb wants and how many GPH you'd need to feed her at WOT?

up to 34 gallons an hour. pressures are usually 4-6psi

Your engine originally came with a mechanical fuel pump. The way I'm reading your question- the original fuel pump has been replaced with an electric pump?

The fuel pump is just a generic auto parts one that was installed over a decade ago and has worked well for some time.

Click to expand...

Ayuh,.... The proper Marine fuel pump with the vent line to the carb would be a Good choice,....

I agree, carbs need 4 to 6 psi,....

Cleaning underfloor tank

Actually it's not the original block, something went wrong with that decades ago and it was replaced with the equivalent auto block, whatever that is, a GM V6 I suppose. This block didn't have the mechanical fuel pump threads punched out so a cheap and nasty fuel pump was purchased.

So I got one from Napa going, 5-9PSI it says, but the float bowl still seats nicely. The old fuel pump was powered on the accessories switch which I will have to change at some point i guess, where is the best place to pull power from for cranking and engine-on states?

My next issue, if you guys have any idea, is the tank under the deck is full of rubbish. I assume it is debris from the inside of the hoses breaking down over the decade it sat for. The sender is mounted in the middle of the tank, maybe 1.5" hole, and baffles either side of it. So two part question, how do you normally go about cleaning a tank out completely with only that access. And... How do you determine the state of the pickup? I assume if it's not accessible it must be an aluminium tube of some sort? (And not rubber or something perishable) Is there a screen over it you can clean or replace or what?

Alarm wiring

And another problem (picking out the tricky ones from my list of two dozen items or so :rolleyes I had the oil pressure/temp alarm go off yesterday for no obvious reason. I left it for an hour in case it was the temp but it came straight back on. Getting good oil pressure on the gauge and good increase when revved above idle (i.e. it is responding correctly)

I disconnected it and have done an hour or two with wakeboarders, with no trouble, so I am sure it is tripping falsely somehow. Is it the alarms fault, or the oil press/engine temp gauges fault, or the sensors fault? How are they usually wired?