M20 producing atrocious mpg. Update 15/6/16

[BenHar]

Yes aimlessrock, I treated that area of the TB last night with lubricating oil as it was particularly corroded.

Two screws came out this morning and the one closest the coolant pipe broke like cheese. Bastard.



Anyone reccomend the best way to tackle this, the screw diameter is particularly fine.

Can't you just wiggle the cover now that there is only one screw holding it?

Then when you have wiggled it off remove the screw stub with pliers.

Ben

[Carmo13]

^^^ This is what i was thinking^^^
Once the cover is off use some mole grips to remove the screw.

[dimebag_from_hell]

Cover won't shift!

Injectors are getting closer tested at the minute if if needed rebuilt.

When replacing them, simply line up the tips with a drop of oil and use some force to pop them in at the same time using the fuel rail? Anything else worth doing.

Should the car be left to idle for 10 mins after they are fitted or is it not necessary?

Thanks

[Cloggy Saint]

Put a light coat of oil on the O rings before replacing them.

[Speedtouch]

Is that advisable? Oil rots rubber.

[Cloggy Saint]

It's advisable. A light smear isn't going to do any harm.

[Brianmoooore]

Is that advisable? Oil rots rubber.

Oil rots rubber, but those O rings aren't rubber.

[Speedtouch]

That's OK then - just testing.

[dimebag_from_hell]

So 3 of the injectors were in particularly poor condition and were leaking slightly, so all rebuilt.

Just need to get the screw out of the throttle body and put it back together tomorrow after work.

[Carmo13]

If the cover wont move, you are going to have to very carefully drill it out.
Use a centre punch to help you start the hole in the centre, other wise you will have all sorts of trouble getting the drill bit to stay central.
Have you tried using a very small flat screwdriver to prise a gap between the cap and TB, then using progressivley larger flat screwdrivers?
Also you could probably get away with giving the cap a few tap with a soft faced hammer.
It looks like its only a bit of corrosion thats still holding the cap on.
Dont get me wrong though, corrosion can get a very good hold!

[dimebag_from_hell]

Cheers carmo13

So got the car fixed I shed last night, returned injectors, new breather pipe and TB gaskets.

The car returned 29.9 mpg today mixed driving, couldn't believe it!

[Speedtouch]

Good going.

[dimebag_from_hell]

The only issue I'm now having is she's taking longer to turn over.

Prior to taking of the injectors, FPR, TB and ICV off, once your turned the key it would start in a split second.

Now you have to wait several seconds, sometimes even turn her of and try again, which was a bit scary 150 miles from home yesterday.

Only thing I did wrong putting her back together was mixing up putting the fuel rail hose and FPR hose on.

Any ideas?

[Brianmoooore]

The symptoms you have are those of a leaking fuel pressure regulator, and you have applied a few bar of pressure to the port of the FPR that was intended never to exceed any appreciable pressure.
This wouldn't normally be expected to cause damage to it, but it seems a bit of a coincidence.

[dimebag_from_hell]

Funny that did cross my mind.

A suck on the vaccum hose going to the air intake from the FPR should confirm it?

[Brianmoooore]

Correct way is to connect up a fuel pressure gauge, run the engine, stop it, and monitor what happens to the pressure. If it slowly falls, clamp off the return hose, and repeat the procedure. If pressure is now maintained, regulator is dud.
In the absence of a gauge, this might work: Run the engine, stop it, then disconnect the return hose from the regulator and connect a short hose into a pot.
If fuel dribbles into the pot, the regulator is damaged.
Alternatively, the pressure loss could be via the small pressure reference pipe to the inlet manifold.

[dimebag_from_hell]

Ok Brian thanks.

Another symptom was a slightly higher idle if that helps.

And just to confirm, the returning hose is indeed that attached to the regulator itself? Silly question I know but I want to get this diagnosed today and a new one ordered if necessary.

[reggid]

This story might be of help or not

i spent ages trying to solve an issue about a decade ago where the car would crank for ages trying to restart a warm to hot engine if you’ve left it for 10-15min or so it was fine from cold or immediate hot start. To cut to the chase I bought new injectors and the issue went away. I had my injectors cleaned but is suspect they actually did nothing so I can’t 100% say they weren’t just leaking. It might have been heat soak into the injector causing a vapour pocket but can’t see how a new injector solves that. If it was pressure bleed off why did the cold start function fine when bleed off would be a bigger factor”¦.

I measured fuel pressure and it does bleed off over time, how much is normal IDK I guess as long as its not very much so that when you crank the engine the pressure builds up quickly all is good by YMMV.
There was a lot of misinformation about if the pump should prime for a few seconds with ignition on or not as mine did not.

There is a check valve in the pump that’s supposed to stop pressure bleeding off and there used to be a BMW inline check valve you could fit that’s NLA but you can get aftermarket ones if you wanted. My pump was new, new FPR, etc tried

If you're able to replicate the long cranking try manually jumping the FPR to prime the system before cranking and see if you can get a different outcome

back to the OP question

Can you damage the FPR if you pressurize it in the wrong way by mixing the hoses?

high idle can be from vacuum leak

[dimebag_from_hell]

Correct way is to connect up a fuel pressure gauge, run the engine, stop it, and monitor what happens to the pressure. If it slowly falls, clamp off the return hose, and repeat the procedure. If pressure is now maintained, regulator is dud.
In the absence of a gauge, this might work: Run the engine, stop it, then disconnect the return hose from the regulator and connect a short hose into a pot.
If fuel dribbles into the pot, the regulator is damaged.
Alternatively, the pressure loss could be via the small pressure reference pipe to the inlet manifold.

Brian how much fuel is acceptable. The hose I grabbed from the shed didn't fit so I just stuck a pot over under the port. I am getting fuel dripping into it, a very small amount but it's visible. If I touch the port with the tip of my finger I'm getting running down it.





So how does the regulator work? Fuel goes into the fuel rail and then into the regulator and fuel then goes back through the return line?

Could the injectors not be seated properly? But I'm getting near 30mpg now so I'm not sure.

Even after a few years stored away it started immediately with old fuel in the car, so somethings happened when putting it back together.

[dimebag_from_hell]

What's everyone's opinion? Is a small amount of fuel coming from the return port acceptable once ignition is off?

Carpartsforless are doing 12% of tonight so will avail on that if necessary.

[Samcez]

I got the injectors (no. 280150716) checked and they are fine, only thing is that they dont spray, they squirt, should they spray or are they fine?

[reggid]

What's everyone's opinion? Is a small amount of fuel coming from the return port acceptable once ignition is off?

Carpartsforless are doing 12% of tonight so will avail on that if necessary.

i cant say for sure but with engine off id say whatever residual was in there should drip out and thats about it. it should not keep dripping out. i haven't tested the amount of drippage myself on a new regulator but it should hold pressure pretty well and there would be some hysteresis in there. if there is fuel from pressure side getting to the other return side then it isnt holding the pressure very well, under pressure test (load) its possible it may not be enough to cause noticeable symptoms.

i dont know how much volume would need to escape to drop the pressure a significant amount. fuel is basically incompressible like all fluids so probably not much.

also on the other side of the regulator if you pull the feed in side hose off even if the pressure on the gauge does decline over an hr or two the line should be "full" and fuel should escape/squirt quickly as you pull it off. if you pull the feed in side off and not much fuel comes out that isnt normal

[dimebag_from_hell]

Correct way is to connect up a fuel pressure gauge, run the engine, stop it, and monitor what happens to the pressure. If it slowly falls, clamp off the return hose, and repeat the procedure. If pressure is now maintained, regulator is dud.
In the absence of a gauge, this might work: Run the engine, stop it, then disconnect the return hose from the regulator and connect a short hose into a pot.
If fuel dribbles into the pot, the regulator is damaged.
Alternatively, the pressure loss could be via the small pressure reference pipe to the inlet manifold.

So I attached the fuel pressure guage to the fuel hose going to fuel rail, started her up and measured 2.5 bar, turned it off and it dropped back to 0 in a few seconds.

I clamped of the return hose and started it but it hit 5 bar immediately, I turned it straight off and removed the clamped return hose. The only way to reduce the fuel pressure was to undo the fuel rail hose.

I started the car again, it hit 2.5bar and now when I turn it of the pressure will not fall and fuel is coming from where the FPR sits on the fuel rail.

[dimebag_from_hell]

Correct way is to connect up a fuel pressure gauge, run the engine, stop it, and monitor what happens to the pressure. If it slowly falls, clamp off the return hose, and repeat the procedure. If pressure is now maintained, regulator is dud.
In the absence of a gauge, this might work: Run the engine, stop it, then disconnect the return hose from the regulator and connect a short hose into a pot.
If fuel dribbles into the pot, the regulator is damaged.
Alternatively, the pressure loss could be via the small pressure reference pipe to the inlet manifold.

So I attached the fuel pressure guage to the fuel hose going to fuel rail, started her up and measured 2.5 bar, turned it off and it dropped back to 0 in a few seconds.

I clamped of the return hose and started it but it hit 5 bar immediately, I turned it straight off and removed the clamped return hose. The only way to reduce the fuel pressure was to undo the fuel rail hose.

I started the car again, it hit 2.5bar and now when I turn it of the pressure will not fall and fuel is coming from where the FPR sits on the fuel rail.

[Brianmoooore]

You shouldn't have started the car with the hose clamped! The clamp should be fitted immediately after the engine is stopped.
Your first test seems to confirm that failure to hold fuel pressure was the problem, but now you appear to have blown the O ring that seals the FR to the rail, and it looks like you've 'cured' the FPR.
It's now had 5 bar the wrong way around, which somehow damaged it, followed by 5 bar the right way around, which seems to have reversed the damage.

[dimebag_from_hell]

I just removed the regulator



So fuel pressure shouldn't drop when you turn the car off?

Cheers Brian

[reggid]

If the gauge is between fpr and the clamped hose it shouldn't fall. If the hose is unclamped it may gradually start to fall over a extended period of time

[dimebag_from_hell]

If the gauge is between fpr and the clamped hose it shouldn't fall. If the hose is unclamped it may gradually start to fall over a extended period of time

Hi Reggid.


I fitted the guage to the hose going to the fuel rail and clamped the fuel hose going away from the FPR, there is no immediate drop in fuel pressure now, that's the way it should be now?

Do you mean fit the guage to the return hose from the FPR?

Anyone know where I can get a new o ring and the plastic ring above it for my FPR? See picture below

[reggid]

If the gauge is between fpr and the clamped hose it shouldn't fall. If the hose is unclamped it may gradually start to fall over a extended period of time

Hi Reggid.


I fitted the guage to the hose going to the fuel rail and clamped the fuel hose going away from the FPR, there is no immediate drop in fuel pressure now, that's the way it should be now?

Do you mean fit the guage to the return hose from the FPR?

Anyone know where I can get a new o ring and the plastic ring above it for my FPR? See picture below

without the clamp does it do the same i.e. retain pressure?

here is o-ring IT4

http://www.realoem.com/bmw/enUS/showpar ... Id=13_0267

spacer comes on a new FPR i know that much. not seen them for sale by itself

[dimebag_from_hell]

Yes without the clamp it retains pressure now. Originally it was dropping to 0 with 2-3 seconds from turning the car of.

[reggid]

behavior seems pretty normal, however given previous tests were suspect and it was over pressurized and pressurized up its back door id be seriously considering buying a new one myself.

[dimebag_from_hell]

New one ordered, what's the chances the injectors are fuel rail have been damaged in the process?

[dimebag_from_hell]

So to conclude, FPR was the issue, now replaced, running perfect and return 30+mpg


Thanks zoners

[Brianmoooore]

We've learnt something new from this - that a FPR can be damaged by connecting the fuel pump to its outlet side.
This happens quite often, following an engine change, when people forget which way around the hoses were, but this is the first time I've heard of a regulator being damaged.

[dimebag_from_hell]

We've learnt something new from this - that a FPR can be damaged by connecting the fuel pump to its outlet side.
This happens quite often, following an engine change, when people forget which way around the hoses were, but this is the first time I've heard of a regulator being damaged.

A fuel pressure regulator had to die, but for the greater good, we are living in a better world now