Phaeton :: Surging Of Engine / Momentary Loss Of Power At Normal Highway Operating Speeds
The primary electric fuel pump in the fuel tank of my 2004 W12 failed last month, shortly after I had set out on a cross-Canada trip from Vancouver Island to Toronto. The whole process of diagnosing and identifying the cause of the problem, mitigating it so that I could continue the trip, and finally replacing the fuel pump was kind of complex, so, here's the write-up.
The problem presented itself as a surging of the engine - a momentary loss of power - at normal highway operating speeds. The onset was progressive, but it didn't take very long - only about 60 miles of driving - from the first little cough of the engine until total failure of the pump. The first indication was failure of the car to maintain speed (while on cruise control) when climbing hills. That progressed to failure to maintain speed on flat surfaces, and finally led to the car coasting to a stop, engine stalled, at the side of the road.
I soon learned that if I floored the accelerator pedal and held it against the floor, the car would cough and burp for a few seconds, then take off like a rocket. So, for the next 40 miles, I coaxed the car into the next city by flooring it, accelerating to about 80 MPH, then coasting until the speed dropped to 20 MPH, and flooring it once again and accelerating to 80 MPH. Fortunately, I was on a remote road with few other cars, and no police.
I checked the fuses for the two fuel pumps - fuses 34 and 35 in panel C (above the left battery), and they were both OK.
The next day, I visited a VW dealer in the Canadian Rocky Mountains, and together with the parts manager and one of the technicians, we looked at the Self-Study Guides (SSGs) for the Phaeton, and looked at wiring diagrams. Eventually, we came to a tentative conclusion that the primary electric fuel pump in the fuel tank had failed. The SSGs stated that the primary electric fuel pump (the pump on the right side of the car) operates all the time, and the secondary electric fuel pump (the pump on the left side of the car) only operates during starting and during 'periods of high demand'. That made sense to us - the car started fine, and worked OK when the accelerator pedal was held to the floor (high demand). It just didn't work worth a darn at any other time... the engine would stall, or, the car would not accelerate at all.
Here are two illustrations taken from the SSGs that describe how the fuel delivery system works. The first image is taken from the 'Phaeton Overview' SSG, which applies to all vehicles. The second image is taken from the W12 engine SSG. I kind of suspect that all the Phaetons operate in the same way, regardless of engine, because the fuel tank in all the Phaetons has the same shape - two lower lobes, which means two pumps are required.
Descriptions from the SSGs
I think that there may be an error in the description above. My experience suggests that the right hand pump (identified as G6, above) is the primary pump, and the left hand pump (identified as G23) is the one that switches on during starting and periods of high demand. Note also how the identification of G6 and G23 in the illustration above is reversed from what is shown in the illustration below. I believe that the text and illustration below is correct, and the text and illustration above is incorrect.
The 'effects of failure' in the description above would, I believe, make sense if it was the left-hand pump that failed. In my case, the right hand pump failed, and the effects of failure that I experienced were as I set them out in the beginning paragraphs of this post - quite different from the 'effects of failure' of the left hand pump that are described in the SSG above.
After coming to the tentative diagnosis that the primary electric fuel pump (the right hand pump) had failed, we checked the parts stock status in North America. There was one pump in stock, but it was in the United States, and being that it was a Thursday, the pump could not be delivered before the following Tuesday. I didn't want to spend that much time waiting for it, so, we started thinking about other possible solutions.
If we could somehow get the secondary electric fuel pump - the pump on the left side of the car that only operated during starting and heavy demand - to operate, that just might put me back on the road again. So, I removed the plastic cover from the small relay that operates the secondary pump, and wrapped a rubber band around the relay, thus keeping the relay in the closed position. A short test drive proved that this solution worked just fine, the car once again operated normally. The only "problem" was that the last 25% of the fuel in the tank would be unusable, because that fuel would be left behind in the right-hand lobe of the tank - the lobe with the defective primary fuel pump.
Electric Fuel Pump Relays
Here is an illustration from the Phaeton wiring diagrams identifying the various relays above the left battery.
Here you can see the two relays for the electric fuel pumps. They are identical part numbers.
Here you can see the relay for the secondary electric fuel pump, with a rubber band wrapped around it to keep it continually closed.
Aside from the loss of use of the last 25% of the fuel in the fuel tank, the car worked just fine with the secondary electric fuel pump running all the time. There were no problems noted even under heavy acceleration. It was, however, necessary to physically remove the rubber-banded relay from its position in the relay panel whenever the car was shut down for more than half a hour. The power to this relay comes from Terminal 30 (battery direct) - it is not switched on and off with the ignition as Terminal 15 power is. This meant that if the rubber-banded relay was left in position overnight, the left hand battery would totally discharge, because the fuel pump would operate continuously all night. I discovered this the morning after the first night...
So, for the next 8 days, I drove across Canada, removing the relay each night and replacing it each morning. I didn't bother to remove it when I stopped for meals or fuel. The rest of the 3,000 mile trip was uneventful - except once, when I let the fuel tank run down a bit too close to the 1/4 full mark, and the car began surging again because the left hand lobe of the fuel tank (with the functional secondary pump) had emptied out. That was a close call, but I managed to get to a gas station and refuel.
After arriving in Toronto, I called the parts staff at my home VW dealer and ordered a new primary electric fuel pump. I discovered that the left and right hand pumps are slightly different (the various hoses coming out of the pumps are different), and I also discovered that a pump costs about $400. The parts staff suggested I order two seals (one for each side of the tank), because I would have to remove both the right and left fuel tank covers to change the right pump. The seals were not expensive.
Here are two pictures that illustrate where the pumps sit in each lobe of the fuel tank. Note the fuel filler port on the left side of the pictures (as we know, it is on the right side of the car) for orientation.
Phaeton Fuel Tank, showing pumps
Fuel Pump Access Panels
Below is a picture that shows where the access panels to the two fuel pumps are. It's easy to get to these access panels, just remove the carpeted panel from the floor of the trunk.
Here's a close-up of the right side (primary) electric fuel pump access panel.
The instructions (from the VW Repair Manual, or the ELSA / ErWin system) for replacing the fuel pump are quite well written. The repair manual suggests that the fuel tank be drained before replacing a pump. I didn't want to drain the tank, so, I ran the fuel level down as low as I dared (remembering that 1/4 full is effectively 'empty' with a failed primary pump). That proved to be adequate.
There are a heck of a lot of steps involved in disconnecting all the hoses and loosening the various components before the pump can be removed. I strongly suggest that anyone attempting this task have a printed set of instructions before starting disassembly.
The fuel pump has quite a few hoses and connections on it, but fortunately, each connector is unique in design, thus it is not possible to hook things up the wrong way when installing the new pump. It is possible to 'lose' a hose inside the tank... for this reason, I attached a small piece of string to each hose I disconnected from the pump.
The process goes more or less like this:
1) Remove the two 404 relays, to ensure no power is sent to either fuel pump.
2) Lift the rubber cover, and remove the electrical connections from both pumps (left and right).
3) Using a special tool, lift up the three fasteners that hold the cap over top of the access panel (these are NOT threaded fasteners!)
Here is a side view of the three fasteners that hold the plastic cap in place - they are friction fit, not threaded.
4) Now you have a clear view of the access panel. It will probably be dusty and rusty, and should be vacuumed clean before proceeding, to prevent crap from falling into the fuel tank when the cap is removed. The rust is due to condensation forming on the cold metal part whenever the car is filled with cold fuel from an underground storage tank.
5) A special VW tool is used to remove the locking ring from the access panel.
6) After removing the locking ring, I buffed it up with a wire brush to remove surface corrosion.
7) The plastic access cap can now be lifted. There are two electrical connectors on each fuel pump, but three possible fittings on the plastic cap. Fortunately, the three fittings are keyed differently.
8) This is what you see inside the tank after removing the plastic cap.
9) After following all the detailed instructions for disconnecting and stowing hoses, disconnecting the fuel measurement probe from the pump housing, etc., it is possible to lift the pump out. It will be full of fuel.
10) The old and new pumps, side by side. I was very surprised at the amount of crap that was trapped in the filter screen at the bottom of the pump. The car only has 60,000 miles on it, and I have always used premium fuel in it.
11) I was also a bit surprised at the discolouration of the pump components. Below you can see the old and new pumps side by side.
12) It is necessary to get access to the opposite side (in this case, the left side) fuel pump, because hoses from each pump travel horizontally across the tank and connect to the other pump.
13) Here you can see a new hose from the right side pump connecting into a T fitting above the left side pump. It is easy to thread this hose across the top of the inside of the tank.
14) As mentioned earlier, there are three possible fittings on the base of each plastic cap, but only two connectors within the fuel tank. Everything is keyed, thus improper assembly is not possible.
Once the new pump has been installed, the hoses connected, and the fuel measuring probe reset into the side of the new pump, re-assembly of everything is quite straightforward. I replaced the rubber ring around the access panel opening on each side of the tank, and I also buffed up the locking rings using a wire brush (to remove corrosion) on each side.
It was not a pleasant job - your hands get covered in fuel, and there are some hazards associated with working on an open fuel tank with vapour escaping, but it is not a particularly difficult job. It is time-consuming, though.
Ford 7.3L Power Stroke (1999-2003) :: Clunk / Vibration When Traveling At Highway Speeds
I'm a mechanic but work only on cars so I'm a little shy on diagnosing trucks. I have a 2001 7.3 f250 4x4 short bed, when I give it gas I can hear a clunk, when I let off of the gas I also hear a clunk. Also when traveling at high way speeds I can feel a strong vibration when I very lightly give it gas but the vibration goes away as I give it more gas.
View 5 RepliesFord 7.3L Power Stroke (1999-2003) :: Surging Noise While Driving At Highway Speeds
I have a 45 min drive to work every day, all highway. Lately on the way home in the afternoon I have been experiencing a surging noise that seems to just happen while I'm doing hwy speeds. It sounds to me like the fan is tuning on and off. Is that possible? It comes on for a few min. And then off again. I have new icp ipr cps. New oil and filter and fuel filter.
Also I'm still having a battery light on and off issue while I'm driving. Is possible the two issues are connected. I plane on doing extensive search for a bad wire this weekend. Batteries and alternator have checked out and are fairly new.
Ford 7.3L Power Stroke (1999-2003) :: Strange Noise Occurs At Both Highway And Surface Street Speeds - Throttle Related
I have a strange noise that occurs at both highway and surface street speeds. On surface streets at low speeds 45 mph and under, if I let off accelerator to coast and lightly step on accelerator I get this quick sharp noise.
Everything I have read regarding a similar noise is under load and being described as a turbo fart. Clearly I am not under any load. I'm lost.
Definitely not a low woooo noise. Also not a hard accel and release and definitely no chuckle and or popping. The sound is high pitched and quick, roughly .5 to 1 second at most. The sound is more like a "zzzrrp" or "zzzoop". I can replicate the sound 50% of the time easily at speeds under 45 mph by briefly coasting (no accelerator) and lightly tapping the accelerator and releasing or holding. Occasionally this sound will occur at full stop when I step off of the brake pedal and before I step on the accelerator. This sound can also occasionally be heard at highway speeds under similar accelerator conditions though it may be more frequent and I just don't notice it.
Would this condition throw a code? Just received "Total Ford Scan Tool Package Enhanced Bundle SP03" scanner from autoengenuity. Hoping to put it through its paces tomorrow.
Additional info: 145k miles. Injectors serviced by a reputable diesel shop here in Vegas approximately 1.5 years ago. Unknown oil leak where oil is collecting in the valley on top of the engine beneath the turbo. HPOP seals were replaced roughly 1 year ago at another reputable diesel shop here in Vegas. Still have an oil leak (turbo related?) Oil is under 500 miles old and acceptable level. Fuel filter is due for a change but that does not seem to affect condition. Air filter 1000 miles. Thinking about upgrading to AIS severe duty kit soon.
Ford 7.3L Power Stroke (1999-2003) :: 2000 - Occasional Miss At Highway Speeds / Bucking And Jerking During Even Gentle Acceleration
165k miles 4x4 6 speed, bone stock unmolested
Slowly progressing problem over 6 months. Occasional miss at highway speeds uphill has progressed to bucking and jerking during even gentle acceleration attempts.
I hadn't got my cam sensor recall done but no change after that procedure completed yesterday. Oil recently changed as well.
I have a torque pro but it never finds any fault codes even though 'service engine' light comes on sporadically. I'm not sure I'm operating it properly but it at least reads rpm when its running.
I'm contemplating the hutch mod but I'd like to have an official diagnosis beforehand if its possible in my case.
Ford F-150 (2004-2008) :: Momentary Moan / Growl And Bog Down At Town And Highway Speeds
5.4L... My truck has a momentary moan / growl / bog down issue. It happens at town and highway speeds and usually when I have cruise on OR when I lightly apply the gas peddle. It moans for a few seconds and seems to bog down then comes out of it and carry's on its way. You can hear it plainly while driving even with radio on. I have a regular muffler on the truck but when this happens, it makes it sound like I have a catback on it.
Things i have done...
- New air filter
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Nissan - 300zx :: Engine Surge At Highway Speeds For Several Seconds Then Drops Back Down To Normal
my 1990 Nissan 300zx with 136,000 miles often surges at highway speeds for several seconds then drops back down to normal. the surge is usually 1000 rpm. does not happen if not in overdrive, and will not happen unless having been driving for 15 minutes or so. also seems to occur more on hot days (80 degree +) than on cool days. mechanic has looked at this several times but not yet able to determine why.
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2003 f-350 6.0 4wd dual rear wheels
4 inch superlift suspension lift, dual shock steering Stabilizer
33 inch wheels.
4 inch turbo back exhaust
Other than that it's really bone stock
Here's what's going on. In 2wd, between 55mph and 62ish mph, once I hit a constant speed, a rumble beneath my feet emerges. If I either speed up or slow down, it immediately goes away.
Does the same thing in 4wd high.
I can eliminate front drive shaft and u joints seeing as they shouldn't be turning while in 2wd. I did notice that when I push up or side to side motion in the front drive shaft, there is a click and a bit of motion. Is that normal? Just a side thought.
When i take off there's a bit of vibration from the rear half of the truck, but I've isolated that to the center support bearing. With all this being said, none of these symptoms were around before I lifted it.
Ford 6.0L Power Stroke Diesel :: 2003 F350 Shakes At Highway Speeds
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I have had an intermittent ABS light for a while now. Since I have gotten the injector o-ring issues, and oil consumption problems nailed down, I am starting to check other things off the list. I have 2 codes:
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Ford 7.3L Power Stroke (1999-2003) :: 2000 - Overdrive Light Blinking Only At Low Speeds
So here's the deal: My 2000 F250 has began to have the overdrive light blink when I am traveling at low speeds <40mph and it is accompanied by strange shifting (lower gear for a longer period of time). As soon as I get up to highway speeds the blinking stops and goes back to normal operation. But as soon as I go back to low speeds it happens again. When I put the truck in to park when it has the light blinking it revs it self to about 1200rpms then goes back to normal idle. This truck has 228k miles and is on the original transmission.
View 5 RepliesFord 7.3L Power Stroke (1999-2003) :: 2001 F550 - Surge Off Idle / No Power
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View 9 RepliesFord 7.3L Power Stroke (1999-2003) :: Surge During Hill Climbing
Decided to try a new wheel to see if I can stop the surge during hill climbing with our 5er. Old wheel looked great with no dusting or nicks. New wheel sure has a whirl when it spools up, but sounds cool. Haven't pulled trailer since swap yet. Truck still only has 85k on the clock.
View 7 RepliesFord 6.0L Power Stroke Diesel :: Subtle Engine Sound Changes While Driving At Highway Speeds - Surging
I've been noticing some weird, very subtle engine sound changes while driving at highway speeds lately. Something almost like surging, but not. I don't know how to describe it. I might try to make an audio recording next time I take it out so I can explain it.
Anyway, I don't know why but ICP popped into my head. Maybe, for some reason, the engine was varying ICP causing the surging sounds.
So I hooked up AE and did a test. I've attached a screen shot.
With my idle speed actuated as high as it will go, and ICP actuated as high as it can go, I can only get a pressure of about 1450 PSI. I always thought ICP should go higher than that. I seem to recall reading somewhere around 3600 PSI.
So am I misinformed, am I reading the data wrong or do I have a problem? How high should Injector Control Pressure go? I missed it in the screen shot, but ICP is actuated to 100%.
Ford 7.3L Power Stroke (1999-2003) :: 2001 - Surge Slightly On Takeoff
2001, 7.3 sometimes surges slightly on takeoff ??
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View 14 RepliesFord 7.3L Power Stroke (1999-2003) :: Idle Surge When Tuned / RPMs Drop To Around 621 - 630 Then Shoot Back Up To 660 - 675
Recently I have noticed that when on a tune other than stock I am getting a surge at idle - my RPMs drop to around 621-630 then shoot back up to 660-675. On my stock tune my RPMs stay around 640-667 and don't cause the surge (felt as a shimmy so to speak). Is there anything else that causes a similar symptom? I attribute it to tuning due to it only happening when running anything but stock but could be wrong.
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I've mentioned in earlier posts that my speedometer has been swinging around wildly off and on, and that on two occasions this has been coupled with a momentary engine stumble. This morning on the way to work it was doing it again but this time the engine stumble happened several times as well. I plan to check the speed sensor, but I wonder how this is also causing the engine stumble?
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