Hot start issue m62tub44
 

M62TUB44 is cranking for ages when hot before it finally starts. Going to try and change a fuel pump and filter to see if that helps, anything else worth a shot? On m60s there's an ECU coolant temp sensor that causes similar issues? Worth changing on m62? Where is it?
Cheers

Mine does that sometimes. It’s very intermittent. I put a new filter on which made no difference and I did buy a fuel pressure tester to see if the fuel supply is the issue ie non return valve but still haven’t got round to checking it. I’m also going to remove the crank sensor and give it a clean to see if that helps.

Same, both with the original 4.4 and now with the 4.6 in the car. Never been able to fix it, even with a new fuel pump, filter and cleaned/flow tested injectors. My fuel filter is the older smaller one which was only used for a few years, and doesn’t have the pressure regulator. My current hypothesis is that pressure occasionally leaks down at the rail, but not always, for some reason, rather than air or spark related.

So I’ve just gotten in the habit of getting in the car and immediately turning the ignition to run, then buckling up and then cranking the X. Has never happened when I follow this routine.

I have been chasing a very occasional fuel vent system code and wonder if fuel pressure could leak down through that system.

Wife's would do this when the FPR failed. Technically just an o-ring. Test the gas pressure at the rail and let it sit overnight. If you don't have 10-20 psi these FPR is leaking back to the tank.


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Thanks Andrew, you are definitely correct. I’ve put a gauge on it and it does leak down, occasionally. I’m just not sure how to fix it, or if there is anything to fix at all since the car doesn’t have a pressure regulator like the ones with the “newer” (larger) fuel filters do. I’m assuming that the fuel pump is supposed to keep the pressure from bleeding down on the cars with the older filter version, but it is only a year old. Hence my theory about the purge/vent system perhaps being the cause.

I asked my wife last night if she recalls it being hard to start when she drove the car daily (bought it new for her in 2002) and she said it’s been doing it occasionally for as long as she could remember.

Hot start issue m62tub44
 

I had 01 with the large filter and FPR built in.

On realoem what does it show for FPR/filter? Yes got to have an FPR or it's not going to have the return line that feeds the siphon jet. Follow the return line to the left tank and see where it goes maybe the FPR is a separate unit on your car.

I thought the difference was weather or not the regulator was removable from the filter not that the regulator was at another location. Anyway, regulator is the least likely cause of fuel leak down.

Thanks Gents. 6/2002 4.4i build car with fuel filter 16126754016. ( https://www.realoem.com/bmw/enUS/par...&q=16126754016 )

I've looked through RealOEM and the car, and can't find a stand alone FPR. Maybe it is built into the smaller filter. If so, then it definitely isn't the FPR that is causing my occasional hard start since the OE filter I put in last year has maybe 10k on it.

Just changed fuel filter with the built in fpr after having a complete no fire incident earlier, too much cranking killed battery so had to be jumped. When I removed old filter it was hot at least 45°c! Will see if that makes a difference before changing pump. Will keep you posted since battery is on charge now. Why did BMW put the fpr on the filter? Why not on the fuel rail like they used to? Means fuel filters are 5x the price than they need to be. Wtf bmw

The filter and FPR can be replaced separately also the filter is good for half a million miles so they consider it "lifetime".

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The o-ring on the FPR, however good for maybe 160-250,000.

New ≠ fixed. Follow the symptoms. You need to check gas pressure after the engine is off.

Also when running: pressure should be rock steady; when my wife's E53 had these symptoms, including the last hard start of taking about 8 cranks of 8 seconds, the dial jiggled with every injector pulse.

Also: people think that the FPR's job is keeping pressure stable, the main job is to hide the symptoms of a failing electric pump.

Ends of life pump (about 5000 hours average), they get weak and won't produce enough pressure to make the extra to also run the siphon jet.

Not having the regulator on the rail saves pumping all the fuel to the rail and picking up engine heat. The processors got fast enough that they can keep up without the manifold vacuum compensation so that was another reason the regulator doesn't need to be on the rail although BMW left the vacuum line in all the way to the engine bay anyway as a vent.
Filters clog depending on how much dirt they are filtering.

It's still playing up, I'll change fuel pump tomorrow, fingers crossed that fixes it!

Yep and the insanely large filter on e53 can easily last half a million miles. You'd have to be in an exceptionally bad area to get enough dirt in your fuel to ever plug that filter. At 180,000 miles I cut mine in half to inspect it was maybe 1/3 consumed.

The tank had less than a gram of dirt at the bottom after ≈ 2 decades. In the USA at least it's pretty uncommon to get dirty gas from mainline stations though I did see a guy posted recently he had a rust issue so a solid preventive measure he took was a magnet glued to the bottom of his tank near the pump foot.

Fitted new pump today, seems to have fixed the hotstart issue. Happy days! Cheers guys

I would still follow up with pressure leak down lest you get caught with a no-start situation due to leaky FPR but awesome on fix helping!

Fpr is new with the new fuel filter. I do have what sounds like a fuel pump whine, is there more than one?

Pumps whine some louder than others. I can usually hear when engine isn't running but not in the car when it's not.

Okay, so don't worry about that then?

Not unless you can hear it in the car while running.

Did you replace the pump only or the assembly with fuel sender? What brand ?

Yeah it's pretty loud, also doesn't sound like it's coming from the side of the tank that the pump that I changed is on, is there another pump on the other side? I thought it was just a sender thingy on the other side?
I only changed the pump itself, think its a pierburg one?

The pump touches the bottom of the tank and will vibrate the whole tank bottom. Take a video or use a tool like FFT app to figure out what relative loudness and frequency.

The unused gas comes back from the FPR into the siphon jet on the left side. There could be audible artifacts but if so I'd bet it's from the o-ring leaking if that's not been addressed yet. Mine sprayed like a garden hose into the top of the tank would definitely be audible.

The foot on the housing gets pressed to the bottom of the tank not the pump.
If you replaced just the pump alone there is a good chance that you might have done something to mess up the isolation to the sending unit/holder. Did you replace the isolators? and are they in the right way? There could be transfer through the hose as well, maybe contacting the housing close to the pump etc.

Hot start issue m62tub44
 

Yes the foot of the *pump* housing. Has a very stiff spring for a very direct sound short to the plastic tank.

Sound will travel much faster thru plastic than air and even though less than steel it will confuse your head where the sound is coming from.

Most notable with the likes of suspension sounds.

Example: when you are on the left side of the car, a sound from the right can travel ≈ 3500 mph though the sway bar, and come though the last bit of air before the direct transmission though the air of the source.

The same could be happening with the pump noise. I would investigate though. If the FPR return line is leaking or will make noise at the top of the left sender unit.

I got sprayed right in the camera lens when I tried to examine the expected drip that was a spray like a garden hose.

Sound advice about the vibration shock absorbers.

That said I can almost always hear the pump from outside any car. I can usually hear inside if the engine isn't running

No obvious leaks, fuel levels not going down, no puddles or fuel smell

Which o ring is this? I've not messed with the other side yet, is there a pump that equalises fuel level across both loves of the tank?

Yep there's a pump driven by the return fuel from the FPR. It has a factory defect and will eventually spray enough fuel into the left tank that it will stop functioning when the total tank volume is less than 1/4 and eventually 3/8 of a tank.

You can find my thread on the fuel supply and I believe it includes the problem and the fix.

There's an additional joint that doesn't even have a seal from the factory.


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Any chance you could throw a link up so I don't have to trawl through your 10k+ comments to find it?

Better to teach a man to fish.

Do an advanced search;

Username: andrewwynn
Title: awr-fix

I put awr-fix in the title of my repair threads to make it easy for people including myself to find the threads.

It's how I find mine or other threads.

Try to find. If you have problems somebody will help but you'll fare much better in the long run learning that skill for finding topic based discussion.

Found it, thanks, the simple search wasn't playing ball for me. Advanced search for it. I don't have the factory obc thing so I can't get hidden test menus, I don't seem to have any issues with my fuel gauge misreading though? Would it still be that sipon jet thing if my cluster gauge is reading right?

Hot start issue m62tub44
 

Hidden menu only uses the trip odometer button to access.

The cluster gauge can read wrong when a sensor is dirty on ether side.

Siphon jet diagnoses requires getting into the hidden menu or a scanner that can read the data directly.

On my e70 I can read fuel level with scanner I don't recall that option with my e53.

The only way to know for sure the tank is reading correctly is to run the tank down to single digits DTE and fill and see if you get 24g of fuel into the tank.

When performing this test, you can monitor test six and avoid fuel starvation with careful observation.

Still no help as my cluster has pixel issues. I have inpa if that's any good but I'm still learning how all that works.

INPA I believe can read anything OBC will tell you.

If you can drive down to E and fill the tank w ≈24g your siphon jet has not failed yet.

Ok, so run it till fuel light comes on then try put a full tank in? 109litres?! I thought they were 81l tanks?

Fuel light comes on with about 14L left. Run until actually empty on the gauge or DTE if you have enogh pixels to read the

92L I believe is e53 tank. The gauge can only read about 81-82 before the float is stuck at the top of the tank. (why the needle doesn't move for the first 80-100km).

okay cool so if the pump clicks out before it's got 80 odd litres in from the empty light then that says it's siphon jet pump issue?

Usually about 20-27L when the siphon will fail.


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Ok so I done some investigation today. The noise is coming from the Syphon jet pump side, the fuel return pipe into the sender unit is vibrating quite a bit, I pulled the sender out and the o ring is in the right position and not deformed. I didn't have a chance to do that other fix mentioned in previous posts as I've got no teflon tape. Would that make the hose vibrate? Noise is starting to get tiresome now

Inlet hose to left tank is fed by the FPR return line. Seems like pump and FPR are not "getting along" and maybe pump is not providing even pressure so the return is pulsed.

T fitting and fuel pressure gauge maybe the only way to determine what is going on

The problem might be that with the new pump there is just the right combination of flow, pressure. pulse, that the syphon jet relief valve is oscillating, it sits in the fuel pump well but pulsations from that will travel back through the return hose. It's a long shot but also a strange problem ;) Was the fuel filter/regulator replaced or lines taken off, is the syphon jet working? Now that I think about it there could be a kinked or restricted line, did you have the syphon jet out before?

Fuel pressure gauge ordered, night try swapping the fuel filter back again see if that shuts it up?

Yeah fpr and filter was replaced, then pump, didn't have Syphon jet out until today, removed it to check tho oring etc mentioned in other posts, all looks good, put it back together, fired it and noticed actual hose is buzzing like mad. All the lines I can see look alright

Non run/start issue?

If needle vibrates at rail = FPR if pressure stable at pump also FPR.

It feels like FPR is oscillating which shouldn't happen but as engine pulls pulses of gas there will be a differential pulse going back to siphon jet. I've jest never heard of it being audible.

You should be able to figure it out with some Ts and some hose clamps. Tap into output from pump and input to siphon. I think that's supposed to be 1.3bar bar (whatever that is in psi) and from the pump I'm guessing 60-70 to have excess after dropping to 50.00 through the FPR.

Fuel pressure gauge needle vibrating with engine running means that there is no air in the system up to the gauge so nothing to do with anything else for diagnostics. The pressure at the pump, rail, gauge will all be the same pressure unless the fuel filter is plugged. The fuel pressure regulator is set to about 40+ PSI so engine running rail pressure will be about 50 PSI because the syphon jet relief valve will add about 8 to 10 PSI which is what the return pressure is. Just wanted to clear up the confusion.

Did you re-use the accordion section of hose from the fuel pump to the top of the sender ??
Back in the day there was often a snubber in the section of line where the accordion hose is on the E53 so if you replaced that section with something else maybe that is a problem.

I didn't change any hoses when replacing fuel pump or filter/fpr.

Hot start issue m62tub44
 

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Before replacing FPR

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49.5 ± 1.3 psi

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After replacing FPR

49.7 It ± 0.3 psi at idle. Also 13 psi after 19 hours.

With W.O.T. I measured about 1psi drop followed by 1psi boost when let off throttle. Saw about 0.3 psi boost on moderate throttle but steady

So 2psi less swing at idle with the fixed FPR o-ring.

No idea where you came up with 40psi. It's known that E53 runs on 50psi and uses milliseconds of injector timing to measure how much fuel per stroke to calculate how much fuel. I don't recall different part numbers for the different engines so I think they all run at 50 psi.

≈ 19 psi is the expected return to the siphon. I don't know if there is additional psi overhead but I suspect there is so rather than 50+19=69, I would possibly expect 80-90 psi at the pump.

When the pump gets weak, it won't supply enough overhead for the siphon and that will give you the same symptoms of a bad siphon o-ring.

Weak psi is the normal ends of life of an electric pump. Unfortunately it's masked by the FPR and worse, also from the fact most people refuel before the siphon jet failure will present itself.

Example: my wife "ran out of gas" with 1/4 tank showing, my dad brought her a Jerry can of fuel and the car started. They decided must be the gauge reading wrong so wife just never let the tank get below 1/4.

She never told me so I got to experience the same, however, at 6°F on a freeway, TWICE.

(Had additional problem of cam sensor, thought that was the only problem due to aforementioned keeping the secret, so a week later car stalled on freeway yet again with 1/4 on the gauge)

Both our e53 suffered the same o-ring siphon failure at 130 ± 3 (k miles).

Wife's FPR failed at 170-180k but mine never failed though 205k.

Both had fuel pump fail almost exactly 5000 hours.

No idea what you are talking about with siphon jet relief adding psi.

There's a relief valve for if there's too much return pressure to the siphon that will vent excessive pressure directly back to the right tank.

With literally 40-50 hours of research on this fuel system never saw one ¶ describing what the relief pressure is where that valve opens and it's implied by BMW it doesn't open under normal use just in case of extreme such as siphon jet pump foot gets plugged.

From BMW : 3.45 bar to engine 1.3 bar to siphon. (never found what is expected from the pump and never needed to directly measure myself).

Educated guess of 70-100 psi (4.8-6.9 bar).

The numbers given above are not accurate for the e53 and the concept of pressure being the same before/after the FPR is also not accurate.

The entire point of the FPR is to take the pump pressure which is by design excessive and regulate it down to what is needed by the engine.

The type of injectors on the e53 are such that they require a known quantity for pressure so they can determine the fuel amount using milliseconds of pulse. A 1 psi differences at the rail will make for a 2% error in fuel supply. Not a problem for the ECU to figure out how much fuel trim to add or subtract to get the air fuel mix to 14.7.

@ Andrewwynn
Is there an X5 sight that you don't post on ?

I monitor about 3-4 but xoutpost is the main one.

I also monitor F10 (wife's) and my current car is E70 but there's much more activity on E53 and I have more experience fixing that chassis.

I was hoping that maybe I could escape from some of your BS and full of yourself attitude but since you are "monitoring" it's unlikely.

You can post accurate info and not get rebuffed. E53 FPR regulates to 50psi.

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There's literally nobody that knows more about e53 fuel supply sorry if it bothers you facts don't care about feelings.

OMG You sure are full of it!

Prove me wrong. I'm correct you are wrong. PSI the same before and after FPR. Nice try. What exactly other than actual facts about e53 fuel supply am I exactly "full of"? My fuel pressure gauge showing 50 psi on the fuel rail of a running e53 is all the facts needed for my case where you said it's set to 40 is incorrect. I'm going to correct errors like that. People correct me if I make a mistake it doesn't get me bent out of shape. Happened a month ago and my reply was "nice catch" not an ignorant ad hominem. When I know what I know I'm going to represent with confidence. I've spent at least 50-60 hours studying the e53 fuel supply and "wrote the book". If you find an actual error I will update my book. Unless you have something correct and positive to say what's exactly your point?

I have explained how the system works to you before but you are too full of yourself to admit that you are wrong. What ever the gauge reading is when the pump shuts off is what the regulator is set to--that's a fact.

Pressure at the pump and at the rail are the same unless there is flow and some restriction at the fuel filter--- that's a fact.

The return from the regulator feeds the syphon jet so any pressure that adds gets added to the regulator pressure--- that's a fact.

If you have a look at the syphon jet relief you will see that there will be fuel coming out of that because in order to have the syphon jets working reliably there needs to be more than enough flow when everything is new--- that's a fact.

No one knows more than you about the E53 fuel system--- BS

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Care to explain why Bosch doesn't agree with you?

3.5 bar is 50.8 psi. The value you will see while the pump is running and definitely NOT the ≈ 45 psi you'll see immediately after turning off the pump.

That value is just what remains when the check valve closes after the pump turns off. Where do you get this stuff?


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Pressure before the FPR is absolutely more than after the FPR. Also the return line is only about 20 psi.

If you were correct about the pressure relief on the return/siphon then cars wouldn't starve of fuel from the return gas going to the left tank. I've never seen evidence of flow from the pressure relief under normal n conditions. You have actual proof I'll update "the book".

When fuel is below 1/3 tank the return line goes to feed the siphon jet. If it went directly to the pressure relief you'd never get the gas from the left tank.

Even if all the fuel pumped (minus the fuel the engine used) went back to the pump the car would starve without the syphon jets working. The syphon jets are fed all the time not just below 1/3 tank. Are you serious?

Above 1/3 tank the two sides of the tank are connected so it doesn't matter if the fuel goes to right or left. So yes, for real.