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Hagerty
Hagerty Employee

An engine problem that "fixes itself" is a lie you shouldn't buy into | Hagerty Media

I was driving the eight miles home along local roads from a doctor's appointment in my 2003 BMW E39 530i, the car I've routinely described as the best daily-driver I've ever owned. It was beastly hot outside, by Boston standards-95 degrees and very humid.
https://www.hagerty.com/media/opinion/the-hack-mechanic/an-engine-problem-that-fixes-itself-is-a-lie...
28 REPLIES 28
DUB6
Gearhead

   I was with you until you stated, "the car is probably only worth $1500" and thus questioned yourself about paying a few hundred to replace the almost certainly guilty parts.  Why is it that every decision - and almost everyTHING, really - has to boil down to dollars and cents factoring?

   Either you like the car and it's useful to you - or not.  Value isn't always about cost or price.  Yeah, yeah, I understand that putting 2 grand into a $500 car isn't a good investment - monetarily.  But what about the sentimental investment?  Or the enjoyment factor?  Can't we decide to do an obvious expenditure on a car just because we "like the car and want to keep it going and safe"?

thehackmechanic
Detailer

@DUB6, I didn't really state things as well as I should've.

My enthusiast cars are generally immune to this kind of calculation. I mean, I have a brown Lotus Europa Twin Cam Special with a highly-distressed original paint job that I just keep dumping money into, way in excess of what the car's worth, because I love the car. The vintage BMWs that I keep for years don't really see an upside calculation. But the E39 530i, as much as I like it, is just a commodity daily driver. The issue isn't dropping a new fuel pump into it. I'm perfectly willing to do that. The issue is more that, because of the complexities of modern cars, it's very difficult to parts-replace your way to erasing the 200k on the odometer and come out of it with a car that you feel is dependable enough to drive anywhere the way you do with a 50k to 100k car. For example, I could drop in the standard cooling system replacement parts of expansion tank, radiator, water pump, thermostat, and hoses, but then there are two hard plastic hoses that run beneath the intake manifold that are a bear to replace. I've replaced them on other E39s, only to have other parts break and strand me. Even if I prophylactically replaced the alternator, I'm still not sure I'd drive the car from Boston down to New Jersey and back instead of borrowing my wife's 40k-mile Honda Fit, as I did last weekend.
DUB6
Gearhead

@thehackmechanic  - OK, this does explain your position a bit better, but it then (to me) just begs this question: if E39s are so doggone hard to work on, and you have no particular love for them, and they only add up to a "commodity daily driver", why the heck did you buy one?  I'm sure, with your knowledge, you could cite at LEAST a dozen example of "commodity daily drivers" that don't have near the problematic stuff (e.g. - two hard plastic hoses that run beneath the intake manifold that are a bear to replace) that this type of car seems to.  Sorry, but I'm still not following you very well.  If I'm looking for a no-nonsense daily driver, I'm not buying something that I know to have parts that "I've replaced...on other E39s, only to have other parts break and strand me" - I'm gonna be looking for something that I KNOW for certain that I can drive From Boston to Jersey (and honestly, I don't even know what kinda drive that is, but it doesn't sound like much in Western states terms 😉).  If it's a known "trouble-producing" car (which this model seems to be, according to your narrative), it's a poor choice for a daily driver, no?

Bmike
Detailer

Seems like a nice enough car. I'd throw another $300 at it (mid-price range pump and filter, and then fill the tank along with a bottle of STP fuel injector cleaner). If the problem returns, maybe move her along.
DUB6
Gearhead

I'm sorry, but a "daily driver" that you can't even trust to go 4 miles because it might stop running on a busy, less safe roadway isn't a "daily driver" - it's a liability.  It needs to be moved along right away.

audiobycarmine
Instructor

My first thought; early in the article, was Vapor Lock.
DUB6
Gearhead

   Good thought, audiobycarmine, the symptoms kinda say that - but...  I'm not an expert on fuel injection, and especially not the BMW kind (being an old-school carb guy), but I'm kind of thinking that pressurized fuel-delivery systems are not as prone to the old vapor lock issues that older, low pressure systems are.  So even though I thought you might be onto something, it just doesn't quite ring the bell for me.

   Seems to me that 50 pounds of fuel pressure would easily overcome any vapor lock - at least in the traditional sense - wouldn't it?  I'm more inclined to think that the delivery system itself, as the author suggests, such as screens or (my number 1 culprit agreement) the pump itself are to blame.

   Of course, I may just be super-sensitive to the "fuel-pumps-are-at-fault" arguments right now, having had to replace one just last week with about 25 minutes to spare before I had to be somewhere!  😁

thehackmechanic
Detailer

Agree with @DUB6; vapor lock is much more likely a problem on cars with low-pressure fuel pumps and no return line.
Mtdesign
Pit Crew

Thanks for the article Rob. I had a similar problem with my 03 Outback H6. With no codes showing up being intermittent. Changed the mass air flow sensor with no luck and then the throttle position sensor which fixed it. This was a 2 month process. That RockAuto part went out in 6 months but I got another one from them that has been working fine. If the car doesn't show you codes than it's just a guess for us DIYers. The one thing we know is that sooner or later the darn thing will fail completely and hopefully not in the middle of Nevada.
Good luck...you'll find it!
gmw
Pit Crew

You can take a lab scope and look at the pattern when the fuel pump is running to determine its state of health. The pattern will show the condition of the armature, brushes, and bushings. If it is drawing excessive amperage, this may reveal a clogged filter. A lab scope is a very powerful tool for diagnosing problems with modern vehicles.
RJ
Intermediate Driver

,,,or an Ohm meter across the fuel pump fuse terminals.
KAM
New Driver

One scenario with in-tank pumps and high pressure fuel injection that is vaporlock-like is fuel pump cavitation at the pump inlet. Similar condition to cavitation on a boat prop - liquid turning to vapor. In this case, the fuel vaporizes at the fuel pump inlet. A return (as opposed to more modern returnless) fuel system brings a lot of engine heat back to the tank with the return fuel. Low fuel level means the in-tank fuel temperature rises quicker (less fuel to absorb the heat). Any chance the fuel in the car was still a winter spec, high RVP (volatility) fuel? That just makes it worse. Back around 2003 when I was working in powertrain development at an OEM I spent a lot of time one summer working on full size vans with return systems in Denver. At the time Colorado was allowing the sale of 10 RVP (high volatility) E10 during the summer. Get some warm weather in Denver (90's) and as the fuel in the tank heated up from driving the fuel would cavitate (turn to vapor) at fuel pump inlet. Since the pump can't pump vapor this resulted in a loss of fuel pressure causing the engine to stall. So we effectively vapor locked the fuel pump in a full tank of fuel. Coast off to the side of the road, wait a few minutes and rinse and repeat. We could eliminate the cavitation by removing the "sock" or "screen" on the inlet that keeps debris out of the fuel pump. Obviously not an acceptable long term solution but reduced the inlet restriction enough to keep the fuel at the pump inlet a liquid. Supplier ended up redesigning the fuel pump inlet geometry to eliminate the cavitation. Just throwing out a couple ideas if the conditions were right. Obviously, as parts age they can become less robust to tougher operating conditions - heat, low fuel, etc. Maybe as Rob noted some debris on the fuel pump inlet screen/sock causing pump cavitation. Many possibilities. Keep the fuel pressure gauge in the trunk.
Swamibob
Instructor

Now there is a most interesting idea. Rob did state the fuel level was low, and if the pick up was not covered in fuel, yes that would cause the problem indicated. I'd also be looking closely at the sock for being covered in crap. I also agree; 'keep the gauge in the trunk'.
Keeping the tank above 1/4 or even closer to half is always a good idea with an EFI car, because the fuel is the only thing keeping the fuel pump cool.
KAM
New Driver

Not to belabor my experience with fuel pump inlet cavitation but a couple of additional facts to share. We were of course logging data on many parameters while figuring out the stalls and evaluating "fixes." The fuel pump current drops to near zero when the pump cavitates since it is no longer doing any work (it is no longer pumping fuel). An amperage gauge on the fuel pump circuit in the cockpit would tell the same story. Also, the fix was a redesign of the pump inlet. Due to manufacturing limitations, the supplier had a 90 degree edge in the pump inlet geometry and they found a way to redo the mold to eliminate the edge.
Jnick
Detailer

I had a similar incident on my 1969 Camaro Z28. It was a beautiful warm day and I was driving on the fast side when low and behold the car flamed out right in front of the local Ford dealer.
Soon the entire mechanics staff ran out to render aid ( perhaps rescued from the drudgery of repairing Ford Focuses) and eventually the car started and seemed to run fine.When I safely returned to Suburban territory the car shut down again and this time it was a no go so I called AAA.
On the following day I started my investigation and when I looked under the car I saw a tiny drip of gasoline on the garage floor. It appeared there was a pinhole leak in the fuel suction line apparently causing the primary float bowl to fill with air and shut down after a while one 2 dollar hose and things were again roaring merrily along!!
Tinkerah
Technician

I know you're not me, and you should be thankful for it, but if you were you'd pull the pull the pump out for a good ol' look see at the inlet sock. If there's not a significant obstruction then certainly keep the gauge in the car while you drive it and possibly a bottom-dollar pump with the tools required since it's among the easiest to replace.
MATTMERICA
Technician

What about Christine? That car definitely had "trust" issues....
Tinkerah
Technician

Yes gremlins, especially computerized ones, can appear and then vanish. My previous car began acting exactly the same way. Good pressure and hot sparks be damned. Bought a "noid" kit to verify injector pulses; all good. Interestingly whenever a noid was connected to any injector plug the car ran great on the other three cylinders. All four injectors connected became a no start issue. I took to driving it with one injector off since it was reliable on three. Months later I was challenged to demonstrate the problem to a non believing acquaintance but when I plugged in the last injector in.....it ran fine on all four. I sold it because "I didn't trust it".
LarryT
Pit Crew

Raise hell with AAA. You are obviously a member through 10/21.
TG
Instructor

Although it was why HAL was presumed to be malfunctioning in the 2001 movie, I have always been a proponent of the HAL method of troubleshooting - run it until it fails, then it will be easier to figure out what to fix. Obviously you will want to keep the car local and have the necessary troubleshooting gear on hand - but sometimes the only way to catch an odd intermittent problem is in the act. Even if you replace the pump and filter you will never be 100% certain it was the cause of the problem
Oldroad1
Instructor

Your lap top indicates O2 sensors driving the injectors rich means a lean condition is present. Before you dive in to anything open the air box and check for a loaded air filter. At the same time clean the mass air flow sensor wire.
DesktopDave
Pit Crew

I enjoyed that article a lot. I haven't owned an E39 yet but I've worked on a few.

I've noted very similar symptoms on many 80s & 90s BMWs are due to the crank position sensors. They don't set codes and become relatively sensitive to temperature as they age. From what I've seen, Bosch seems to have used them as an informal sort of fuel-cut safety mechanism. If the DME is unsatisfied with the CAS signal, it will cut fuel by opening the fuel pump relay circuit. A quick fix is to jump the socket with a bit of wire/paperclip/hairpin/etc..

Of course the later cars were also bedeviled by the EWS nonsense, but that's a far more difficult issue to describe in a blog reply...
Swamibob
Instructor

Another good thought Dave: I hadn't thought about a Crank Sensor. Probably because I don't work on BMW's. 🙂 Can you do an ohm test and find one going bad? Possibly using a hair dryer to simulate a warm day?
DesktopDave
Pit Crew

Yep, a resistance test is BMW's recommended method. Combining that test with a hair dryer could work out well. Some of the external-mount types can be also be adjusted closer to the crank tone ring. Also be aware of motors also use the trigger wheel as an external vibration damper ring. I've seen one or two that delaminated, causing a significant deviation in the crank angle.

Sometimes all they need is a good cleaning; I bought a '91 BMW 318i that started right up after I cleaned all the oil, grime and metallic debris off the crank sensor face.
Fifth87
Pit Crew

@thehackmechanic Rob, please do keep us posted. I am fighting a similar battle with an Oldsmobile at the moment. Hoping your findings might point me in the right direction, as all my troubleshooting has been for naught.
Timm
Pit Crew

You bought a boat anchor and after owning it for a while find that you aren't happy with what's taking place. Get a real job and quit sniveling about Your lack of maintenance and but a honda (yetch) or something else that you can buy cheap and drive into the ground as it's crap to begin with.
I hate to read about some one buying a car that, because of it's name it's a Great car. A Great car does just what it's designed to do relative to original (as new) purchase price. These kind of stories are boring, try something else for employment as what you do now is not worth reading as this takes place all the time in High School parking lots.
Gary_Bechtold
Technician

I had a fuel pump issue that took over a year to figure out. Car died on me once. Let the car sit a little and it started back up. A year later it did it again. I can't remember but I believe a few months later or weeks is when it did it a third time . I eventually had to have it towed to a shop nearby and we replaced the pump. No issue for years since figuring it out. At least yours failed in quick succession mine took a year plus to do it again.
BobthePhish
New Driver

Rob, I also had a 2003 BMW 530i with around 200k on it do the exact same thing. My step-daughter was the one driving the car (do to my procrastination fixing her Jetta), and lived an hour and a half away. When it would die on her, she'd have it towed to me. Of course, by the time AAA towed it to me, the car would startup and run normal. This went on for about a year, with maybe 4 breakdowns over that time. I finally had her leave the car for a week and I drove it. It acted up on me finally on a hot day in traffic, exhibiting classic running out of fuel type symptoms, also wouldn't restart. I had a stranger at the gas station I pushed it to crank it while I smacked the top of the pump cover with the lugwrench. It started and I booked it home, put my fuel pressure gauge on it and all was normal. I work at an Indie Euro shop, so I ordered a Valeo pump assembly for around $150 as an educated guess. It ran another year with no more breakdowns before getting T-boned by a guy running a Red light. Put a fuel pump on it.