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View Full Version : Loud noisy buzzing fuel pump & P0087 / P2047 codes


idakiteman
07-12-2019, 02:29 PM
In case this may help others, I share this problem & repair experience (with a few pictures):

PROBLEMS:
1) We purchased a 2006 Itasca Navion RV in late August 2018 (11 months ago) in San Diego, only 50k miles. Early during the drive home to Boise I noticed a loud buzzing that appeared to be coming from underneath the cab. I was not experienced enough with the vehicle or diesel to say if it was present when we first drove the vehicle upon pickup, or if it started shortly thereafter. Anyway, I found vibrating fuel lines coming from the gas tank. Google search on this symptom came up with reports of a recurring issue with the high pressure fuel pump regulator causing this fuel line buzzing. One author described this and said he’d had that buzz for 200k miles, so it wasn’t a functional risk, only an annoying noise. So I drove with it for about 3k miles no problems.

2) Then, in late June 2019 on a trip climbing a steep grade, the CEL/SES light came on, and the RV when into limp mode, little power, only slow driving. I had an OBDII code reader & it reported P0087 and P2047 codes (generally, low fuel pressure…insufficient fuel). I could clear the codes and resume normal driving, no problems on flat ground or mild grades, but on steep grades when I stepped on the petal to kick-in the turbo, the same faults would happen again, and I could again clear it and resume driving. If I took it easy on grades, downshift & go slow, easy on the gas pedal, it would not happen.
Because the behavior, and the codes, suggested a fuel starvation problem under load, and then also the loud buzzing underneath, I suspected the in-tank fuel pump. I crawled under the RV’s tank with the engine running and could then hear and feel the in-tank pump buzzing very loud inside the tank.
INVESTIGATION:
I dropped the tank and removed the fuel pump assembly. The fuel pump motor sits inside a plastic canister and the bottom of that canister, surrounding the pump, showed much dark brown/blackish particulate contamination. Also the bottom of the plastic assembly (that sits on & contacts the bottom of the gas tank) had some of this contamination. A small diameter hose coming from the pump assembly sticks out about a foot and has a plastic cone shaped strainer on the end. This hose also sits on the bottom of the tank…a fuel pickup hose. It’s strainer was completely clogged and encased in this same debris. But this line is not big enough to be the only fuel pickup source. With In-tank fuel pumps, usually the entire bottom end of the pump motor is the main fuel pickup location, at that intake end of the pump motor is covered by a strainer sock. So I disassembled the fuel pump assembly (it can be done) to pull out the motor and have a look. The underside of the pump was completely caked with this debris. It looked like a dark brown/black felt cloth was affixed to the end of the pump. Turns out, this was not felt but gunky particulate buildup. Although you couldn’t see it because of the gunky build-up, rather than having a larger strainer sock, this pump has a fine wire mesh in the form of a cap that snaps onto the end of the pump. The picture shown is after I scraped some of the junk off with a straight-edge...there was even more than shown. After scraping off the “felt” gunk I could see there was a screen of some kind, and I could pry it off with a screwdriver. That strainer was totally clogged with this same dark brown semi-solid debris…looks like dark brown/black sawdust that breaks up & mushes when you squeeze it. The inside of the pump was clean, shiny metal, no sign of debris there thankfully…so the strainer cap stopped most of this contamination. Clearly this contamination significantly interefered with fuel pickup, making the fuel pump work harder and likely causing cavitation which would produce vibration.


So then I looked inside the tank, and later tested the main fuel filter (located in the engine compartment) and fuel supply line between pump and filter.
REPAIRS:
FUEL PUMP. I cleaned the strainer cap to like-new condition, and cleaned the contamination from all parts of the pump assembly. I reassembled the fuel pump assembly, so it was “clean as new”.
GAS TANK. Inside bottom of the tank was coated with this debris sticking to the bottom. It could be seen and felt. Sides & top of tank were smooth & clean. But the bottom clearly contaminated with this stuff stuck to bottom, but some loose enough that it can migrate. I cleaned the entire tank with white rags until no black/brown staining appeared on the rags. Then I poured in fresh diesel & swirled it around, and poured it out filtering the pour through white gauze cheesecloth so I could verify it was particulate free & clean. I cleaned the tank to “new condition”.
FUEL FILTER. I had a new replacement filter on hand and chose to test the flow-thru of the old filter compared to the new. A simple test was to blow in the “inflow” tube and feel the “outflow” tube while feeling how hard you have to blow to feel outflow air. It was immediately obvious the fuel filter was also obstructed and presented much more resistance to fuel flow than the new filter would. It wasn’t totally clogged, but was significantly restricted flow. I installed the new fuel filter
Clearly, the combination of obstructed fuel pickup (clogged pump intake strainer cap) and the obstructed fuel filter put extra load on the fuel pump making it vibrate and buzz.
FUEL SUPPLY HOSE FROM FUEL PUMP to FUEL FILTER: I inserted large diameter stiff line from a weedeater string trimmer into the fuel hose, acting like a “roto-rooter” spinning & plunging the line back & forth. I got the trimmer line down the entire length of the fuel hose and could inspect what came out. Nothing did. The hose showed no debris coming out, and on removal of the trimmer line was clean.
I installed the cleaned fuel pump into the clean tank, and reinstalled the tank, and of course the new filter.
OUTCOME:
The buzzing is completely gone. The in-tank pump is so quiet you can’t even hear it. A test drive up a long steep grade produced no check-engine lights or fault codes, and performance was great. The entire low pressure section of the fuel supply systems in now in like-new condition again.
LESSON: Modern ULSD fuel is much more prone to precipitate solids when stored long periods, and prone to growth of organic contamination AND LOTS OF CRAP. ADDITIVES TO COMBAT THESE ARE CRITICAL WITH EVERY FILL-UP. KEEP SPARE FUEL FILTERS ON-HAND, and try not to let fuel sit in the tanks for long periods.

The Grand Tour
07-12-2019, 07:06 PM
Good job!

Midwestdrifter
07-12-2019, 08:26 PM
After looking at that crud. I think its a combination of corrosion byproducts, and microbial growth. In steel tanks with significant water content, the steel corrodes, and microbes grow at the water/fuel interface. That mix of garbage usually gets picked up by the pump filter before it comes out the nozzle at the station. Looks like you pumped fuel from a station without filters, or with failed filters...