My solution for fuel pump problems on 5.7 Gi and Gxi Penta

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

I did some more digging, and found the source of the voltage regulator that I bought. Suntekstore is the source, and this is the description of what looks like the best fit; "Input AC/ DC 12 - 45V to Output AC / DC 0.7 - 21V 8A Converter Board Step-Down Voltage Regulator Module". They have a few others.

They are not currently offering the unit that I bought. Shipping was faster than I expected - about a week.

Cheers
Rod

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

If you hear the loud buzzing noise, switch off the engine and check which fuel pump is hot. One pump is likely to be cool.

The pump that is on the outside of the fuel cell and replaceable without dismantling the fuel cell is the high pressure pump. It is possible to buy this pump on it's own without buying the whole fuel cell unit.

I haven't been able to find the low pressure pump available standalone. It would be great if someone could source it and publish the source here.


The hot pump is likely to fail soon unless you change something to save it. At least get a spare pump so you can replace it quickly.

Cheers
Rod

 

[Tail_Gunner]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Do you have the ability to measure voltage as the rpm increase's....aka where is the point or rpm level which no longer require's voltage adjustment.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

The controller I have installed maintains a constant voltage at the high pressure pump.

As the pump load increases, it takes more amps from the voltage controller, at constant voltage. In the stock installation, as the pump demands more amps, the supply voltage goes down a little because of resistance in the supply wires.

I have not measured the voltage setting on my setup.

What I am monitoring is the fuel pressure at the injector rail. And when I set up the voltage controller I experimented with higher and lower settings. I adjusted it to have a small amount of recirculation through the fuel pressure regulator at idle (which you can feel and hear) , and then carefully load tested it at gradually increasing loads, to make sure that the fuel pressure never dropped below the specified level.

It helps that the pressure regulator lowers the fuel pressure at maximum load from Volvo. The injectors are programmed to stay open longer at high engine load to counteract the reduced pressure.

I hope I have addressed your question..

Best
Rodregal

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

I realized last night that there is an ambiguity in my post yesterday, so this is to further clarify;

At low engine loads, the injectors use small amounts of gas, and obviously at full load the injectors are open for longer pulses and draw more fuel through the rail. The delivery pressure at the rail does not vary by much from idle up to full power.

The changes in load/demand on the HP fuel pump are caused by the changing pressure of the gas on the suction side of the hp pump. At full load, the pressure regulator sends almost all the gas straight to the injectors, and the pressure of the small flow of gas through the recirculation line which goes back to the suction side of the hp pump is at a very low pressure. This causes the hp pump to work harder. High amp draw.

At light load, the amount of gas flowing to the injectors is much reduced, and the pressure regulator recirculates a much higher volume of gas at much higher pressure, back to the suction side of the hp pump. This results in a very low pressure difference from the suction side to the pressure side of the pump. So the pump has a light workload, and draws a low amp current.

I hope this helps!

Rodregal

 

[dacarter]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Good info in this thread. I have an 03 Gi-D 5.7, but so far no fuel issues.

Be cautious about leaving the fuel gauge on the engine long term. In the Porsche 928 community I participate in, some of us used to leave a small FP gauge on the rail until there was a failure and fire.

 

[larson260]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

I posted earlier in this thread and said that I would ask my mechanic about this pump issue. As expected I got a "as is breaks fix it attitude". Between now and when I cook my new pump assembly I think I should carry a new H.P. pump on board. My gxi and your gi are the same. Do you have the part # for the H.P. pump only.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Thanks dacarter for the warning.

I am concerned about that issue. I have a remote sensor/gauge combination that I would like to install, but I may not for just that reason.

The gauge I have on the engine now - I will remove it soon anyway.

Rodregal

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Hi Larson260

I found the receipt. I got it from Marine Parts Source, and the part number is VP3588865 I paid $238.50 .

Sorry for the delay!

Rodregal

 

[mavic11]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

wow this is the exact problem with my 5.7. I just replaced the fuel assembly due to intermittent whining with a new one but even the new HP pump runs super hot. I will try to find a voltage regulator asap.

just for reference, i have closed cooling and both old and new pumps are models 21608511

 

[NoExcuses]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Check your fuel pressure on the fuel rail. You still might have a restriction somewhere in the delivery system.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

To add to what Noexcuses said, the fuel pressure regulator mesh intake screen is a likely place for blockage. Volvo have published a simple change for this - removal of the screen and insertion of a special spacer. You have to put a pressure gauge on to see.

I have had fuel blockage from the black paint in the fuel cell blocking the pressure regulator. It caused a high rail pressure of 90 psi, and fuel starvation.

But the blockage, in my case, did not cause the high pressure pump to overheat, or make the buzzing sound.

Let us know what you find!
Rod

 

[NoExcuses]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

My problem with Volvo fuel regulator service bulletin is if the paint doesn't get stuck on the regulator won't it just get stuck somewhere else like the fuel injector screens? I'd rather pull the regulator and clean screen opposed to pulling 8 injectors.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

I agree completely NoExcuses. I suppose the injector screens may be less likely to clog up - but who knows?. The whole set up, with the black paint and the imbalance I have found which consumes the HP pumps at a rapid rate is very unimpressive.

There are many Volvo customers that are getting poor reliability and worse, and wasted money and time - and Volvo could easily tstep up and take a proactive approach.

 

[mavic11]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Well I got the voltage regulator, hooked it up to the HP pump but apparently its too weak. Input was 14v and output could never get above 1v and you could hear the engine chugging and starving for fuel. The regulator got really hot which is rated at only 2amps. I just order the 8amp version from amazon so to be continued...

any ideas why only some 5.7s HP pumps are affected? I asked on the Stripers Owners Club and someone replied his pumps are cool to the touch.

 

[Don S]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

any ideas why only some 5.7s HP pumps are affected? I asked on the Stripers Owners Club and someone replied his pumps are cool to the touch.

Good question, any time I have found hot pumps, there was a problem with the supply of the fuel to the pump. Air leaks in the system before the pump, partially plugged pickup tube or anti-siphon valve
In my opinion this voltage regulation is just covering up the real problem. But, since it sounds easier than finding the real problem, they all want to try this.
Way too many Volvo's out there running without this problem.

 

[mavic11]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Im at wits end and dont want to shorten the life of my new Fuel Assembly. I replaced the hoses, check valve and new fuel assembly but the HP pump still runs very hot at idle. The old pump had intermittent whining at idle but was fine when cruising. This hack is my last resort...fingers crossed.

thanks.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Mavic

When you put in the 8 amp voltage controller, test the output voltage with no load - it should be possible to adjust up to the input level. If not, then solve that problem first.

Don has a good point that the suction side of the system can leak - allowing air in. If that happens the air will likely cause cavitation and failure of one or both pumps. To check for this what I have done is to connect a schrader fitting and hose to the low pressure pump output (the schrader valve that is on the side of the fuel cell), then turn on the LP pump while immersing the end of the hose in gas in a clear bottle. If you see bubbles continually (you will see bubbles initially anyway) then you have an air leak on the suction side. As Don said.

The air leak could be in the pickup, or the connections on the suction side of the LP pump, or in a hose, etc.

On my setup in the medium past, I had a leak in the pickup - I had to replace both pumps. For me, changing the pickup was far easier than setting up the voltage control system.

Another variable here which might explain why some boats don't have a problem is that the internal functioning of the float and other parts inside the fuel cell may be subject to failure. I disassembled my fuel cell and worked on it, but I did not test those functions. It would be interesting to hear back from owners who have.

Hope this helps!
Rod

 

[pfunkmixer]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

I have 2004 5.0 gxi same setup if you have the whine noise first off are you using non -ethanol fuel
had this problem a couple years ago whine from high pressure pump, I was using ethanol fuel (attracts moisture) regular pump gas when sitting that moisture kills the pump over time white and red rust occurs. I found this when I disassembled my fuel cell. It is not recommended to disassemble your fuel cell unless you are mechanically experienced. Bench tested my low pressure fuel pump, cleaned the rust out and still running.

Whine=high side pump starving for fuel (usually) overheat condition fuel pressure should be @50-60 psi
because low side pump is the restriction should be 4-5psi

(FUEL CELL)low pump pulls fuel from tank through separator to fuel cell reservoir high side pulls fuel from reservoir and pressurizes fuel rail

IF YOU CAN FIND JUST THE LOW SIDE PUMP/ MANUFACTURER/ PLEASE POST I'VE TRIED JUST ABOUT EVERYWHERE

DO=use ethanol free fuel - most ethanol treatment is snake oil especially if it says it removes it. all it does is try to bond to alcohol/water molecules to atomize when fuel sloshing around in tank to help burn more effectively some I've tested separate from fuel immediately some are slower stabil ok but not impressive

DONT=run motor with out water cooling (raw)(hose)smoked my high side pump trying to put a surface charge on my batteries for a couple minutes

If you don't hear a whine and motor is running like **** (rich,black smoke,misfiring no power) high side pump malfunctioning possible, low pump pulling fuel in and flooding reservoir in fuel cell, after it floods goes to vent hose on top of reservoir and dumps it right into the manifold, easy check pinch vent line with some pliers while running to see if it smoothes out when you release will probably stall

I don't believe changing fuel pump speed but i do believe in trying to keep it cool.

 

[rodregal]

Re: My solution for fuel pump problems on 5.7 Gi and Gxi Penta

Hi Pfunkmixer, sorry for the delay in my post/response.

I am using gas with Ethanol, which I know tends to clog up fuel systems. I don't think that is a primary cause for the problems I have had.

I spoke to a guy who races drag boats and is very knowledgeable about Ethanol, he said that Ethanol deposits are impossible to wash off with petroleum based products. He recommended the cleaner "Simple Green" (assuming you have the fuel system off the engine).

I have found that the black paint deposits accumulate most in the inlet mesh for the high pressure pump, in the pressure regulator, and in the inlet mesh of the injectors. The worst of these is the inlet to the high pressure pump, which is difficult to clean. But the HP pump is easy to remove - about 15 minutes. I had my injectors off the engine and had them cleaned and balanced. Even though their inlet mesh had a lot of black paint in them, they flow tested within 3% of each other before cleaning, at about the correct flow rate. Because the filter itself is before the fuel cell in the flow of gas, it does not get clogged with black paint. It will accumulate water if you have any in your gas.

The Low pressure pump - I am 99% certain that it is not available on it's own. I have searched extensively, and I know others who have too.

I measured the temperature of the gas at the fuel rail on my engine, and at idle with the HP pump at full speed (ie the factory setting) the gas temp reached 125 deg F (long time at idle, temp gradually builds). Running at full load the temp dropped off to 85 with ambient temperature of 70. (because of less gas recirculation).

I hope this helps!
Rod