Volvo Low Pressure Fuel Pump Seals? - Pump Whinning

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smithder

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I just bought a boat that has a Volvo 7.4 Gi PWTR engine. It is running great, but the LP fuel pump starts whining after it has been idling about 3-5 minutes. It sounds like it is caveating, then it passes the air and a few seconds later the cycle starts over with a quiet whine that gets louder until it passes.

I found a post with the exact symptom, but he ended up replacing the pump with an aftermarket which I didn't want to do. The PO told me this pump was replaced a while back and the boat hadn't been used but a few times since. I am thinking maybe it is somehow sucking air. I put a new filter and yesterday I removed the filter and topped it off with gas to ensure I didn't have trapped air in the filter. No change. I have ran it with the gas cap off. No change.

I am wondering if when they replaced the pump on of the fittings is not completely sealed allowing air to be drawn in??

The pump gets hot and I would like to correct this before I damage the pump, or end up stranded somewhere.

Thanks
 
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BRICH1260

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You might pull it and check the O rings for condition and replace as needed. Check for debris or blockage too. If possible, could you add a ring of sealant to help seal it better.
 
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Silverbullet555

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In addition to the above....

Is the tank full or low. If low, you can fill it and see if that corrects the problem. If there is a leak in the fuel pickup it could suck air. Not sure if it would cause the symptoms, but an easy check.

You can also try replacing the anti siphon valve on the tank and the hose from the tank to the fuel cell.

Rebuilding my fuel cell is on the list of things to do. Hoping to wait until fall.
 
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smithder

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When I picked up the boat last weekend I know the fuel was old so the first thing I did was drain the tank and replace the filter. I used a clear hose to and connected it to the hose that attached to the fuel filter/LP pump. I had no bubbles during the siphon. I then put 35 gallons of new gas (92 gallon tank) and ran the boat in the water for about two hours. Ran great, but the whining comes and goes and the pump is hot.
 
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smithder

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Does anyone know what orings are in this assembly and if Volvo or an auto parts place has them? I'll pull the pump when I get home. We are supposed to take the boat out tonight and I am hoping the pump doesn't crap out.
 
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BRICH1260

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The O rings are specific size and are Vitron made to resist gasoline deterioration. You might be able to find replacements at an auto parts store, just make sure that they are gas/oil resistant. Volvo does not list them as an orderable part, but they can be purchased by other online venders. I remember reading a thread that lists the size and vendor. You might try doing a Google search.

You might also check and make sure that the fuel cell cooling system is working properly, water in and water out. As if not the cell could be overheating, causing a vapor lock condition.
 
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smithder

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Ok Thanks. Does the sucking air theory sound right to you guys or should I be looking for a new pump?
 
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BRICH1260

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smithder said:
Ok Thanks. Does the sucking air theory sound right to you guys or should I be looking for a new pump?
Click to expand...

I`ve never heard of the "sucking air" theory on pump squealing. In most cases people have claimed it is due to screen clogging due to dirty fuel or paint particles. I would think that if air could get in, then fuel could get out. But I am no expert, others may be able to confirm your thoughts though.

You might give some more specifics on what year of engine, hours, ect. as someone may have experience with the exact unit.
 
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smithder

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The fuel was dirty and I was able to dump some particles/sediment out of the old filter, but no water. Mostly the gas had turned a dark color.

Whats up with the paint chips? I read that too. I will pull it and check the screen and orings before throwing money at a new pump.


The boat is a 2000 Formula 260 with 360 hours on it. 7.4Gi PWTR
 
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smithder

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Mine doesn't look like the video. It is two separate pumps. One in the front with the filter and one on the back.

I picked up a new pump. I'm just going to go ahead and swap it rather than risk breaking down an a new to me boat with the wife and kids. I'd never hear the end of it. Lol
 
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BRICH1260

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smithder said:
Mine doesn't look like the video. It is two separate pumps. One in the front with the filter and one on the back.

I picked up a new pump. I'm just going to go ahead and swap it rather than risk breaking down an a new to me boat with the wife and kids. I'd never hear the end of it. Lol
Click to expand...

That's the best choice. Now you can take the old on apart in the off season and see if you can refurbish it. If so, maybe you cans keep it as a spare or sell it on ebay to someone having a similar problem.
 
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