Bloody Calibra

[020 Brad]

I've been doing a bit of work on the Calibra to try and get it up to a standard to sell. Oh how I want to just set a match to it/put on trademe for way too cheap, not running and not legal.

Aaaaannnnyyyyway.. it's been running quite crap and after seeing Chad sort out his issues I decided to replace the spark plugs and change out the fuel pump. I did this and it started up after sitting and ran perfectly! Success, or so I thought.

After a couple of minutes of smooth idling it started missing and just running like crap. I shut it down and pulled the plugs to check what was going on. All looked well (the old ones were near new and very black like it's been running rich). I changed out the idle control valve, which isn't that fun a job. Next I started it up again and no luck, it was just running on a couple of cylinders and being a dog generally.

I was really baffled, and started going through a few checklists. I pulled the dissy down and all looked good. It seems to be getting good spark. So I checked the fuel pressure nozzle on the fuel rail - nothing!

Due to this I assumed it wasn't getting fuel, so pulled the pipe off the pump to clear and air lock and still nothing. I spent ages cranking the pump on a battery (so I didn't need to have the car turning over, because we'd already spent a long time cranking it to try and get fuel anyway) - the spare battery was connected straight to the fuel pump.

I decided it was low on gas or not picking up for some reason, so went and got gas twice, but after sticking 10 litres in thought this can't be the issue. Finally I had to siphon the fuel out of the tank to get it picked up and to the tank - the Bosch pumps are very poor at picking up fuel when they are sucking on air.

Finally it was pressurising and I was getting fuel to the fuel rail! I was almost ready to start it again when I saw fuel pissing out from under it and it appears the pipe leading to the pump (low pressure) is perished and cracked, and pouring fuel out before it even gets to the pump. Excitedly I decided to replace this, but soon realised I need to drop the whole fuel tank to do so.

So, tonight I dropped the fuel tank to replace a simple hose. What a crap design. No access plate in the Calibra, but there is in certain Vectras?! Stupid f**ken thing. I got the pipe replaced, re-attached everything. Got it started and..

Ran perfectly

...for about 2 minutes until it started missing and eventually dropped to a couple of cylinders and stalled after another 10 seconds or so. I checked the fuel in the fuel rail - nothing! WHAT THE HELL!!

I guess it could be the fuel filter next, so I'll replace that I maybe swap back to my other pump considering there is probably nothing wrong with it.


/just needed to vent

[020 Brad]

Oh crap. That's a long read.

Short story: I'm having a fueling issue with my Calibra that was difficult to trace and still isn't resolved.

[001 Neville]

Sounds like you're on the right track anyway, Brad.

Hope you get it sorted soon.

[168 Derek S]

vent away if your happy to type, its all good reading.

when you put the new inlet hose onto the pump maybe leave it long and drop the new pipe inlet tail from the pump and shove it in a full fuel can (on the ground), take the old pump inlet pipe that's still connected to system and drop that into another unfilled fuel can too, this way you can prove circulation, if your still having problems at the fuel rail end then look at the pressure bye pass valve (or that's what I call it) at the fuel rail

basically moving fuel from one fuel can to another.

I hope your injectors are not dirty?

when I checked mine I run a set of leads with alligator clips off a spare battery direct to the pump first of all

[127 Gordo]

Hahaha, sounds familiar.

With mine it was a problem that developed because some FFFFing shit for brains noddy replaced that section of hose with a piece of HEATER hose - of course, it was stuffed by the petrol and eventually was sucking in air.
I had around 35 litres when i had to drop the tank, so spent ages with some 8mm ( I think) plastic hose trying to syphon most of it out.
Easy fix when I had access, though.
With you, it may just be flushing the fuel through - don't forget, the bleed is at the top of the rail and so any air in the system is going to be trapped there - if it's under pressure, you're on your way, just may need a few more tries.
If you know someone coming up this way, or going down there, I've a fuel pressure testing kit you can borrow.

First things I did when I got mine was to do a oil change, all the filters and the plugs. Unfortunately, I didn't check the gearbox oil level - hey, no sign of leaks - unfortunately, instead of 2.1 litres it had about a 1/2 litre - after 5k or so it developed a dif' bearing noise...

[020 Brad]

Yeah you guys are onto it. Fuel pressure regulator may be faulty, or even not getting a vacuum?

The pressure definitely builds, I nearly got myself a petrol shower by priming it up direct from the battery before the hose clamps were all done up and the high pressure pipe was right about to pop off. But, as the engine runs it progressively loses pressure. I'm looking towards the rear, thinking fuel pump or filter but it could be towards the front, being the fuel pressure regulator or perhaps even a broken, blocked or kinked hose up on the high pressure side.

I had really good pressure and no air in the system when it was all primed, just before I started it. I was shocked at how much pressure was there - it makes it really exciting that the nozzle is in the exact position that it spray fuel/vapour directly onto the exhaust manifold! But as the car runs it slowly loses fuel pressure until it cuts out.

I have a spare everything, and an entire running engine in my track car, so I guess I can just keep on replacing things until it comes right!?

[021 Chad]

I was running with no vacuum on the FPR for months, it didn't affect fuel delivery at all, it seems that the FPR on these really only kicks in to drop fuel pressure at idle, or so Gordon and I surmised as neither of us had FPR vacuum connected! AFR was fine on the dyno too.

Perhaps though the FPR is completely stuffed? This could cause an issue I suppose.

Good luck though buddy, I'm sorry now that I was bragging about getting mine idling nicely

[020 Brad]

Good luck though buddy, I'm sorry now that I was bragging about getting mine idling nicely

haha, it's ok. I didn't realise I had such a big problem on my hands back then! I thought throwing those parts at it would sort it out.

Further things I have noticed - the diagnostics (or what ever it is) plug that sits at the back of the engine bay by the fuel pump relay was unplugged? And the plug that you can turn around is set on "A" rather than "B". What are others set to??

[127 Gordo]

If it's not maintaining pressure, could be a dirty filter - a bit messy to replace as they tend to let petrol down your sleeves.
I ended up replacing the vacuum take off on the FPR, as I figured it may have been designed that way so best to replace it - it drops the FP from 2.5 Bar (Motronic 2.5) to 2.2 at idle and under vacuum.

The fuel pressure relay (incorporates the ignition) is well known for playing up, but usually when starting up - $104 from GM but a lot cheaper from overseas - I cut up the old relay case and cleaned the contacts as a spare after taping the case back on. Depending on model, it'll either be behind the driver's footwell panel or under the bonnet in a black cover towards the back of the compartment, behind the gearbox.

The plug doesn't affect the XE management, in lesser models it alters the innition maps for different actane fuels. That's also where you bridge a couple of terminals to read error codes - nothing showing in the dash?

I've got a spare 2.5 Bar rail, if yours is the distributor engine - the later dis'pack uses 3 bar and Chad may have a spare.

[020 Brad]

Didn't sell.

I'm going to try a third fuel pump, as I ran it up again only on the pump connected straight to a battery and you can hear cavitation. The car is on a lean but I jacked it up to be horizontal and then let the pump prime for about 5 minutes with nothing else running. I started it and again, it ran perfectly and had good fuel pressure, but slowly began to drop cylinders until it was clearly about to cut out. I turned it off and checked the fuel rail again and it was just air! I don't know how air is getting into the system, but I'm going to say faulty fuel pump and hope I'm right! It's a Bosch unit from a VL Commodore, which are generally quite reliable and it was running only a matter of days ago, so heres hoping.

[168 Derek S]

I would be looking closer at the fuel pressure regulator, vacuum connection and the fuel pump relay as Gordo suggested above

[127 Gordo]

If you're still getting air in the line, I can't see it being a pump problem.
one thing I forgot, they use a sort of telescoping pickup and I suspect that it's possible for air to be drawn in past the slip loint - no evidence, but there have been a couple of times I've had plenty of fuel in the tank and had a temp' problem with air in the lines. Also had it with a little over a half tank of fuel at Toupo - I figured the fuel sloshing around was putting pressure on the lower section and the flex was allowing the air in - either that or I was getting plenty of lateral loading on the corners and the pickup was getting exposed. The next time down there, with better tyres, I didn't let it get near half - kept it topped up and no futher issues.
I've got a spare pickup/cover assembly, if you want to have a look the next time you're up - you could borrow the fuel pressure testing gear at the same time?
Certainly seems to be something on the pickup side of the pump!

I doubt it's the case, but many years ago one of the fault trucks had a really annoying fault and would sometimes cut out but if left for a while would start up and run until the next time - turned out to be a rag in the tank that would now and again get sucked onto the pickup pipe and, when left, the rag would drop off as the vacuum was lost until the next time...

[020 Brad]

I have a spare tank, so will look at that option. What a nightmare though, dropping the tank with 30 odd litres of fuel in it It does make sense though, and could explain why the cavitation. Ohwell, I've got the other fuel pump now so will try that first and see if theres no result.

It can't be the ecu, wiring or relay, as I had bypassed all of this when I was running the pump off a spare battery and the fault still occured.

It could however be a faulty fuel pressure regulator possibly, that could be letting air back in from the LP side or possibly not holding pressure. Doesn;t really explain why so much air gets in. I think the most likely is probably what Gordo suggests of a faulty pickup.

Cheers guys.

[168 Derek S]

suggest this is worth a read, although about mechanical injection there are some interesting points around the fuel pumping side of things and where check valve on pump is

http://www.auto-solve.com/mech_inj.htm

and this

http://opel-scan.ru/files/Opel_Motronic2.5.pdf

[020 Brad]

On Gordo's advice I dropped the tank to check the pickup. I inspected everything and all looked well, which was slightly disappointing, BUT! All was not lost. Upon removing some of the hoses I realised that the hose that I "replaced" with a second hand hose originally has sprung another leak! Well, not so much a leak but a pin-hole so small that no leak was apparent but it could intake air into the system.

So, tonight I dropped the fuel tank to replace a simple hose. What a crap design. No access plate in the Calibra, but there is in certain Vectras?! Stupid f**ken thing. I got the pipe replaced, re-attached everything. Got it started and..

Ran perfectly

...for about 2 minutes until it started missing and eventually dropped to a couple of cylinders and stalled after another 10 seconds or so. I checked the fuel in the fuel rail - nothing! WHAT THE HELL!!

So, have now replaced this hose with a new high pressure (even though it's on the LP side) hose and all appears to be well!

Fingers crossed.