8.1 Volvo Penta Fuel Pump Issue

[Big D]

Looking for a source to test a fuel pump off a 8.1L Volvo Penta. Low pressure fuel pump started making a buzzing noise. Engine idled ok but died shortly after you raised the RPM. Checked the fuel pressure and had zero PSI on the low PSI side & 25 psi on the high pressure side. Next day the buzzing noise was gone & I'm now getting 5-6 PSI on the low PSI side & 35 PSI on the High PSI. Boat seems to run fine but concerned that this issue might present itself again. From what I've read, the PSI should be 10 & 50 PSI?

On a side note, I've had battery trouble with the boat. Thought the alternator might be bad but it tested and it's putting out 14.6 volts. One of the batteries ended up being bad even though it's only a 1-1/2 old. I suspected that low voltage out put from the alternator could cause an issue with the batteries & possibly the fuel pump but doesn't look that's an issue.

Any input would be greatly appreciated.

 

[Shlbyntro]

If your buzzing, the fuel pump(s) are likely on their way out. Not a whole lot you can do about it except preemptively replace them

 

[Big D]

If your buzzing, the fuel pump(s) are likely on their way out. Not a whole lot you can do about it except preemptively replace them

Can they be rebuilt? Good source for a replacement?

 

[Shlbyntro]

Volvo says no, they can not be rebuilt and you need to buy the brand new $1,300 unit and replace it as a whole.

 

[Tpltrbl303]

What an appropriate post… I just ordered a new one today


Sent from my iPhone using Tapatalk

 

[Big D]

I see several "new" ones offered on ebay in the $200 range? Seller's with 98%+ rating. Are these an option or junk?

 

[Shrub Lurker]

I’ve used a few of those aftermarket units. Bought from 350jr on eBay. Nothing failed in the past three years.
per my supplier the OEM units are on back order with no promise date.
Looks like I can do three of these and still be cheaper than one OEM.
my customers know what they are getting and realize the savings. The supplied cooling hose is too short and the supplied filter needs to be pulled and lube applied to the gasket.

 

[Big D]

I’ve used a few of those aftermarket units. Bought from 350jr on eBay. Nothing failed in the past three years.
per my supplier the OEM units are on back order with no promise date.
Looks like I can do three of these and still be cheaper than one OEM.
my customers know what they are getting and realize the savings. The supplied cooling hose is too short and the supplied filter needs to be pulled and lube applied to the gasket. View attachment 1023456

Thank you for the feedback

 

[DRYHEAT]

I have used after market deals like posted and had no issues. I’m sure they probably make one for the 8.1 also.

 

[DaveH]

its entirely possible the noise the pump is making is cavitation from a lack of fuel. clogged filter? broken fuel pickup? i would be looking into this before I replaced the pump.

 

[Big D]

Picked up a new pump off Amazon for just over $200. Swapped out the old one & boat seems to run well. Getting 12 PSI off the low PSI side and around 40 on the high PSI side. I read somewhere that the fuel pressure should be around 10 & 50 PSI? Should I be concerned about the 40 PSI? Boat is a 24' deck boat that rarely see's over 3,500 RPM since it lives on a lake with a 35 MPH speed limit.

 

[Shrub Lurker]

Picked up a new pump off Amazon for just over $200. Swapped out the old one & boat seems to run well. Getting 12 PSI off the low PSI side and around 40 on the high PSI side. I read somewhere that the fuel pressure should be around 10 & 50 PSI? Should I be concerned about the 40 PSI? Boat is a 24' deck boat that rarely see's over 3,500 RPM since it lives on a lake with a 35 MPH speed limit.

Run it. You will be fine

 

[DaveH]

Picked up a new pump off Amazon for just over $200. Swapped out the old one & boat seems to run well. Getting 12 PSI off the low PSI side and around 40 on the high PSI side. I read somewhere that the fuel pressure should be around 10 & 50 PSI? Should I be concerned about the 40 PSI? Boat is a 24' deck boat that rarely see's over 3,500 RPM since it lives on a lake with a 35 MPH speed limit.

if the specification is 50psi and you are at 40......that's roughly 20% decrease in fuel delivery. think LEAN. will it run? sure...and depending on how conservative the tune is from the factory......you MIGHT be ok, or even pick up some fuel economy. then again.......if its tuned for emissions....you may now be lean for extended and hard usage.

 

[Racey]

if the specification is 50psi and you are at 40......that's roughly 20% decrease in fuel delivery. think LEAN. will it run? sure...and depending on how conservative the tune is from the factory......you MIGHT be ok, or even pick up some fuel economy. then again.......if its tuned for emissions....you may now be lean for extended and hard usage.

New flow rate is calculated by taking the square root of new psi divided by old psi multiplied by the old injector flow rate

so 40 psi divided by 50 psi = .8

square root of .8 is .89

So 89% of the original flow rate. 11% difference.

Still a pretty drastic difference.

 

[Big D]

Anyone know what PSI it should be? I'm only stating 50 psi due to a YouTube video I watched. Old pump was only producing 35 PSI on the high pressure & only 5-6 on the low PSI side.

 

[guest hs]

The 8.1 pump is different then the all the other pumps. Hope you got the right one

 

[SBMech]

You are probably not taking into account the fuel pressure regulator, when vacuum drops (you hit the throttle) it raises fuel pressure to add fuel via raising pressure..think accelerator pump. So you should see 48PSI or so when you snap the throttle then it will drop back to 40ish. IT can be 10PSI, it can be 6PSI, but you want to see it jump UP when you snap the throttle, never go DOWN.

Buy yourself a factory manual if you are going to do work yourself, you CANNOT guess at specs with fuel injection, or you run the risk of burning shit up.