I guess I possibly might be over simplifying how the pump works, in my head I’m thinking it’s mechanically driven from the camshaft, so as long as there’s fuel in, if the camshaft turns there should be fuel pumped out unless the pump is faulty. But I’m wondering if there’s something electronic controlling the flow in, maybe stopping it totally. Maybe a faulty fuel rail pressure sensor would totally stop any flow from the pump?

 

@danny1313

DTC P1065 suggests low rail pressure at key engine rotation time, which means the fuel system is unable to reach the required operation pressure.

The above code can also bring on DTC P0087.

I believe your problem may be the over / under fuel rail pressure relief valve on the end of the fuel rail and we have seen issues with this valve many times and it is either failed or stuck in the open position and sending all the fuel rail pressure / fuel back to the tank.

Your target rail pressure should be approx. 30MPa/300bar at engine cranking and has to reach a minimum of 20MPa/200bar for the injectors to actually be allowed to operate by the ECU. You need a local mechanic capable of checking your rail pressure to check this for you.

It could also be a failed injector therefore I would suggest an injector leak-back first which is the easiest test to do, and it would rule out any issues with the injectors.

Honda error code P1086 causes which need to be checked and eliminated,
1/ Large vacuum leak on engine
2/ Faulty Mass Air Flow (MAF) sensor
3/ Faulty fuel injector
4/ Low fuel pressure – Need to know what the fuel rail pressure is because you report 600 kpa which is only 6 Bar.
5/ Ensure the connections on the fuel rail pressure sensor are tight and not corroded.

 

thank you @UK-Kev, I was considering investigating the pressure relief valve however currently there is no fuel at all coming out the pump when cranking. I'd disconnected the circled red pipe in the image below which I assume is where fuel should flow at high pressure if the engine is cranked.

If the pressure relief valve were stuck open/failed would it shut the pump down so nothing comes out?

I'm also confused by no error codes reappearing after I cleared them, I'd expect a P1065 at least to be logged if I crank the engine and there's no fuel coming out the pump. Not convinced I have the best code reader but it was able to originally read and clear the codes.

Before looking at the rail and injectors I thought to confirm pump and fuel supply was ok, but maybe there's something on the rail shutting my pump off. Fairly sure it'll be something obvious but I'm baffled at the moment.

 

When was the last time your fuel filter was changed and is it a genuine Honda one?

 

tbh, not sure it's ever been changed in the 10 years we've had the car. For now I've bypassed this, using the following setup, thought I'd try getting it running from an auxiliary fuel supply first.

 

@danny1313

Okay I see you are using a gravity fuel supply and you still do not have any joy in starting the engine.

If we presume that the over / under relief valve is okay, then you might have a problem with the high-pressure pump and possibly the fuel transfer pump.

A sudden stop of running engine could be the injector drive off the end of the camshaft either sheared off, or the camshaft drive dog spinning and not driving the high pressure pump >>> See Video

 

A sudden stop of running engine could be the injector drive off the end of the camshaft either sheared off

I think you may be spot on........am I correct in thinking this shouldn't be spinning freely?

I wonder if it sheared off after running the new pump for a few seconds

 

@danny1313
Yep, That's the problem the drive dog should not be spinning in the end of the camshaft that is why your engine is not running.

Fix the drive dog spinning and you’ve fixed your problem.

BTW Do not try arc-welding because it does not work.

If you have court the problem in time and you can get the drive dog out, you may be able to use some Loctite 638 Green High Strength, Retaining Compound……. Please note this may not work and you will still end up having to change the camshaft.

On some later engines of this design of drive dog Honda had a roll-pin inserted to stop the drive spinning – Hence if you have a good engineering company that could handle this job, but again this involves removing the camshaft.

Item 4 on this link >>> https://www.parts-honda.uk/honda-ca...nda-cars/CR-V-DIESEL/2006/SE/ENGINE/CAMSHAFT-CAM-CHAIN/17SKN501/E__1100/1/20219

 

Thanks @UK-Kev . This had baffled me for a while, frustratingly I'd checked it before fitting the new pump and it seemed secure.

Thank you for the diagram, very helpful, I'd not been able to find one. Off to take a look to see if the drive dog comes out now.

Found a photo online of the assembly. Gently tried to see if the drive dog was totally loose - it didn't appear to be - unsure if this is good or bad, was worried bolt A might drop off, maybe it has already.

Am I correct in thinking turning bolt B clockwise should screw it back into bolt A? I guess another possibility is the gear is totally knackered and spinning against the camshaft.

Wondering whether next step is to attempt removing the cam cover which I suspect might be challenging as not sure the injectors have been removed in over a decade. A job for next weekend!

 

@danny1313
I have just been advised that sometimes the 17mm nut comes loose on the gear and this is what causes the loss of drive because the gear is on a tapered shaft.

FYI albeit I know of this problem I have never had the pleasure of working on the fuel pump drive unit for this very early engine, so if you could post lots of photos it will help folks in the future….. Thanks

 

@danny1313
How it works – Gear number 3 is driven by the camshaft, held in place by bolt 17.

On item 4 the fuel pump drive dog (the large bit on the left) think of this as a bolt, which goes through the housing item 4 and held down with bolts 24 and 22 and this is held in place with nut and gear on item 4.

Item 4 gear and nut is the one that comes loose.

Hope this helps.

 

👍 will take plenty if I manage to get the cam cover off. I suspect I’ll be posting a thread on how to remove stuck injectors soon 😂

I did read some comments on the YouTube video you linked asking if there was a special tool to tighten the drive dog, it looks like something is potentially required to hold it whilst torquing bolt A (in the picture).

My garage condemned my crv as scrap so if it’s just a matter of tightening up the bolt it’ll be a result- but a long way to go yet 😀

@danny1313
How it works – Gear number 3 is driven by the camshaft, held in place by bolt 17.

On item 4 the fuel pump drive dog (the large bit on the left) think of this as a bolt, which goes through the housing item 4 and held down with bolts 24 and 22 and this is held in place with nut and gear on item 4.

Item 4 gear and nut is the one that comes loose.

Hope this helps.



View attachment 168536

I think we cross posted, I’d missed your last post. Thank you for the diagram and explanation. Will leave the injectors soaking in wd40 this week and see how I get on at the weekend

 

@danny1313

Found a very old video clip showing the nut that has come loose - First few seconds of video

Link >>>

 

@danny1313

Found a very old video clip showing the nut that has come lose - First few seconds of video

Link >>>

Great find, thank you Kev.

It looks a trickier nut to tighten than I'd imagined

It's also got me wondering how tight it needs to be, maybe too tight would stop it rotating, but too loose and it would quickly fall off. I'm hoping the direction of rotation is keeping the nut/bolt tightened rather than trying to unscrew it.

Will be interesting (and I'm sure stressful ) to find out more if/when I get the cam cover off.

 

@danny1313
Been advised that the torque setting is 87lb/ft and it is a 17mm nut - You might want to confirm this once you have the camshaft cover removed.

 

Made some small progress yesterday. Injectors removed, bits of the auxiliary components removed.
A few challenges yet to over come, rounded a nut holding something to the cover, broke my T25 socket removing the injector clips, and dropped my 10mm socket down the back of the engine - I think its resting on the plastic under tray 😩.

Need to work out how to remove all of this pipework on the side of the cover next, there's a lot to remove to get the cover off, hope I can remember how to put it all back together.

I found a few specific posts mentioning the same issue I have now

https://www.crvownersclub.com/threads/fuel-pump-drive-nut-came-loose-that-turns-cog.226821/

https://www.crvownersclub.com/threads/high-pressure-fuel-pump-drive.190025/

https://www.civinfo.com/threads/2-2-diesel-hp-pump-problem.248001/

It's got me thinking, I think on my original pump the lift pump aspect of it failed as it didn't pull fuel into the pump (I think) as only worked when hand priming. The 'working' second hand pump I fitted whilst it worked momentarily, I'm wondering whether it has actually seized (maybe whilst stored). I notice the shaft doesn't spin freely like my original one, it's much stiffer/more resistance. Reading some of the other posts this nut that becomes loose sounds to be by design to prevent a seized pump damaging the camshaft/engine.

Ideally I'd send both pumps off for testing before refitting but I think testing is about £150 per pump.

So a difficult question if anyone is familiar with these pumps, how much resistance should there be spinning the shaft.
Should I be able to spin by hand or need to put a spanner on the shaft to rotate?

 

@danny1313
Hello Danny, Think we all know the pain you are going through.

Your plastic bit in your picture just snaps together over the wiring harness.

Regarding your question on the pump and I am presuming you are talking the High-Pressure pump (See Picture Below) Yes you can rotate the pump using the gear or the retaining nut – You will feel the pump turn easy and then very hard as it overcomes the spring on the Polygon Ring and then repeats easy then hard again as you are turning it.

Now if you have removed the fuel transfer pump from the back end of the HP pump, this should rotate very easy with hardly any resistance.

 

Thanks @UK-Kev. A bit more progress. 10mm socket recovered, rounded nut removed, pipework just about moved out the way enough. Can't for the life of me find how to move the wiring harness but removed enough connectors to shift slightly.

Cam cover off!

The offending loose nut

No room for a socket/spanner in there, struggled to figure out how to tighten it. In the end jammed a screwdriver against the nut, and stuck an Allen key in the oldham nut, not convinced I've managed to apply much torque .

Fairly sure there should be some form of tool to tighten the shaft, I notice the oldham has 2 holes which look like it'd be suitable for some form of tool to crank some torque on. Or even simply something that fits in the drive dog slots. Not having a welder or and metal I wasn't able to fabricate anything.

Investigated 2 pumps further, the 'good' replacement is definitely much stiffer, fairly sure if I manage to successfully get it all back together the torque required to spin the pump will be greater than I applied to the nut. I read one similar thread where the poster hadn't applied enough torque and it failed within 5 miles only for him to strip everything down and retorque. Not sure I'm going to be that dedicated to fixing the old girl, but will do some googling to see if I can find something to torque further without removing camshaft.

Original pump - suspected failed transfer/lift pump

Replacement secondhand pump

 

@danny1313
Your fist video – The high pressure pump sounds a bit noisy to me and was probably the cause of the nut coming loose.

You should be able to get a 17mm open ended spanner onto the nut to hold it and with reference to the above video you should be able to use a 3/8 drive extension and locate it into the drive slot and tighten the nut to the required torque setting.

 

Thanks Kev, been trying to figure out a means to torque it insitu, but struggling slightly.

There isn't really anything to put the 3/8 drive extension into - this is how it looks:

What I did try doing was using the oldham in the slot:

Tried using a Allen key and spanner to start but later found an 8mm hex driver fitted.

Got to about 30Nm (was aiming for 115).....and the nut cracked...luckily I have a spare

I really need some kind of slot driver that fits like where the red line is below, but not managed to find anything so far:

 

Danny,

Cannot understand why you tried torquing the nut up using the Oldham drive and an Allen key, no wonder it broke.

The Oldham drive is just to take-up the oscillations between the two drive units.

If you do not have the tools or you cannot fabricate something to do the job correctly, then your only option is to remove the high-pressure drive pump unit from the engine and do the work on a bench - Or have you phoned up your local Honda dealers and asked them if you can hire / borrow the special tools.

 

yeh, unfortunately I'm limited as to the tools I have with no means to fabricate anything. Was really hoping to avoid removing the camshaft, especially as I wasn't sure whether either HPF pump was good.

On the plus side, all back together, turned the engine, wouldn't start, was just about to give up, when bingo, engine jumped into life.

Amazing, the old girl is running again, still slightly dubious how long it'll last so pondering whether to fully strip down and torque up the drive properly, but wondering if that's a bit beyond my skill level as I think the timing chain needs to be removed.

 

Like I said previously and from listening to your HP pump on your video it sounded noisy and think it contributed to the drive coming loose.

Did you fit the new pump?

Good news on getting the engine running again.

 

yes, fitted the new (second-hand) pump, the one with the stiffer movement that I wondered whether might be seized. Now have the dilemma as to what to do next, might speak to my original mechanic and see if now I know exactly what was wrong and what needs doing whether they'd be able to sort it out properly.