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Stanky's fixerating of vehicles thread - Daewoo fuel pump examination and diagnosis 30/12


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2 hours ago, lisbon_road said:

You're welcome.  Either you can borrow it or we could do the test here.  Either way, probably depends how much of a rush you are in. 

I'll be heading up to Salisbury in the Mercedes, the prospect of the Daewoo bogging down and/or dying entirely in the M27 roadworks and having to bail out of a car in a live running lane is giving me the jitters just thinking about it! I'll drop you a PM shortly to sort if thats ok? I can bring the Diagnostic laptop up with as a hostage swap too if you wanted to see if you could get it talking to your Astra as well?

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Thanks to the kind offer of a compression tester from @lisbon_road, I don't think its the worst possible outcome. Measured from cold, all 4 cylinders read 220psi/15bar compression without needing to add any oil or anything - this suggests to me that the valves and rings are still good and the misfire issue is elsewhere.

Since I had them all out anyway, I replaced the plugs with the brand new ones I had here. I made sure they were gapped to 1.0 - 1.1mm as per the manual and with it all back together I took it for a drive. It seems OK now, the idle is smoother and it wasn't misfiring, though I wasn't able to go very far, or crucially test it driving up a steep incline.

The plugs I removed - which are all of 2500 miles/18 months old looked OK, there was a small amount of oil round the base of the worst one, but what I did notice was the electrodes were all covered with white deposits, rather than the usual orangey-brown. The tips aren't melted, though the insulation has browned a bit? The engine doesn't run hot (conversely, and due to another manufacturing novelty of GM Korea at the time, these don't run at 90c, at best it sits between 1/4 and 1/2 on the temp guage. The thermostat has been changed, its just the way these all are). 

PXL_20211218_131531979_MP.thumb.jpg.f9c2f328b2f3a3efcf1964761bad378f.jpg

The timing should be fine, its had the cambelt replaced by a real garage within the last 3 years and they timed it up, its certainly no different to how its always been. I get no error codes for fuel mixture being too lean, but don't really know what I should be looking for here?

The plugs (both ones removed, and new ones) are Bosch R6s which is what various motor factors recommend, might these plugs be running too hot and thats my issue? There is no visible damage to the leads, and no error codes from the coil packs (except when I disconnected the 2x king leads when I was compression testing, which threw a code for each of the 2 coil packs - so I know they are monitored by the ECU and will throw error codes if they are faulty (which they aren't doing).

 

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Good news about the compression test.  I'd have a look at fuel trims to check that it is running a reasonably sensibly and the lambda sensor trace to check that it looks ok too.  I wouldn't be too concerned about the temperature gauge as the effect of different senders and gauges can make a nonsense of what they seem to be telling you. 

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My own two penn'orth: those plugs may be 2500 miles old but if they've sat in the engine and done a few cold starts then sat and stewed in their own juice that would end them quickly. 

I agree check fuel trims IF obd equipment allows, if not find a hill and go up it low revs/high gear and try and recreate your previous fault condition. 

Then if it's all ok, give it a good Italian tune up to clear its tubes out

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  • 2 weeks later...

As suggested on my for sale thread, I removed the rear seat of the Daewoo this evening and lifted the sikaflex'd on access hatch to get at the in-tank fuel pump.

Prior to this, I needed to play musical-cars to get two working cars onto the drive so they could be used, and the Daewoo into the garage where its dry so i could work on it. It had sat for 4 days, but was a complete bastard to start, churning over fine, but not firing. Eventually it burst into life after very careful balancing of the accelerator pedal and settled into a normal idle. This might or might not be relevant?

Anyway, with the lid off the access hatch, I knocked the retaining ring round, unplugged the wiring harness, unplugged the two fuel lines and lifted the combined pump and fuel gauge assembly out. It pissed fuel all over the shop, initially it was normal petrol colour, then it vomited some hideous dark brown muck all over the floorpan under the rear seats. Frustratingly, I couldn't see exactly where this foul grot had eminated from, but it was definitely from inside the pump housing.

Having removed the housing completely, I tipped it upside down into a mop bucket to see what colour the VERY EXPENSIVE premium petrol that came out was. Oddly, it was normal greeny-clear, with no bits or discoloured grot at all.

I then set about taking it apart to get at the filter element at the bottom. I'll get some pictures of this tomorrow, think of a teabag that pushes tight onto the pickup spout and you're about there. This was browny, and after removing the filter from the pickup pipe, I washed it in the clean petrol in the mop bucket and a load of gritty browny-black crud came out. I kept washing it in the petrol bath and it seems cleaner now. Is this normal? The fuel I can see in the actual tank is crystal clear.

I'll reassemble the pump and whatnot tomorrow and see if its running any happier, how likely is it that the in-tank pump filter was mega gunged up and wasn't delivering enough fuel to the engine, causing the misfire? Incidentally, the pump thats in there has writing on the side, suggesting its a replacement from a scrapper anyway. The Sikaflex sort of backs this up...

Last question - how likely is it that the actual pump mechanism is weak/failing/full of shit and that it may be failing to deliver enough fuel to the engine, causing the misfire? I have no fault codes relating to fuel pressure or pump issues, but on a car this basic and old I doubt there are sensors for it anyway. I'm clutching at straws but wondered if the old plugs I removed - which had white tips, potentially suggesting it running lean - might be pointing towards a weak or blocked fuel pump. This is 100% speculation though.

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  • Stanky changed the title to Stanky's fixerating of vehicles thread - Daewoo fuel pump examination and diagnosis 30/12

Few thoughts.  One thing I picked up as a tip from a man in Australia (gotta love the internet) is that to clear a blocked pump, get the filter off and tap the pump and run it backwards by reversing the polarity.  I saved a Sierra pump that way.

Normally fuel starvation will show up when demand is greatest, one acceleration at decent revs, as the engine will start to miss badly when you boot it.  I've seen that on a Chinese countryside bus running on petrol.  Just chugging along it is less likely to be noticeable.

It isn't something I have seen, but perhaps short term fuel trims would go up if there is starvation as the mixture leans off.  I can't really see it restricting fuel at all flow rates unless really blocked up but perhaps others will have more experience of that.  To answer the question, no for me those tea bags strainers are normally pretty clean and a decent yellow colour.  

Sounds good that you've found something wrong and might have fixed it though.  Just get it back together and see what happens.  

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Thanks - appreciated and understood/agree re the fuel starvation at higher revs point.

Initially I suspected the coil packs as the misfire manifests most at low revs, and can be provoked by lifting off the throttle entirely at ~40mph, letting the car coast in D down to about 25mph, then trying to accelerate back up to speed. This is pretty much a surefire way to make it stutter to varying degrees.

Booting it when it starts to misfire usually clears it - unless going up a steep hill in which case it just seems to bog down and drop to firing on 2 cylinders (I think). It being a auto makes it difficult to drive around the issues, or at least harder than it would be if it were a manual when it could be left in a gear lower than normal and probably be about 80% better.

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For me, this is at the point of just trying it now you have cleared that filter.  Even if the pump is also suffering, the cleared filter should make a big difference.  If someone else can comment on how fuel pump starvation/blockage etc can show up in live data, that would be interesting.

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Pump reassembled and refitted this morning, having cleaned it out as best I could and refitted the filter teabag. It took all of 15 minutes to do so relatively easy.

I've put my life in the hands of the shite gods by taking the car to collect the new years eve takeaways, I'm at the first stop, pizza hut. A 5 mile drive so far and it's behaving perfectly. Nice stable idle and no misfires at all so far. Next stop is the Indian, then home so I hope it's now sorted. If not I'll eat all the pizza and walk home.

If it stays ok then I'll look to get a brand new pump unit from AliExpress for £55 delivered, since this one is clearly old and tired and full of crud

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21 minutes ago, lisbon_road said:

I reckon you've fixed it.  Great news.

Up to you, I'd not bother with a pump.  I think a lot of these pumps are interchangeable, judging by the ebay listings that include a wide variety of cars.  Well, Happy New Year Huw. 

Sad to say I've jinxed it, just back home now and it ran badly all the way back. Back to misfiring unless you boot the accelerator and keep it above 3000rpm for a bit. Then it is ok for a few miles before the misfire returns.

Fuck it, it's off to silverlake in the new year, I just don't have the patience or time any more

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Hi Huw , how much mot is on it , if a few months its gotta be worth a secondhand pump or a cheapo pattern part one, you now know how quick and easy it is to change ,gotta be worth a try  .

More importantly how was the Indian takeaway , hopefully the split gunge from the pump wasn't too pungent .

Have a good one 👍🏽

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1 minute ago, mitsisigma01 said:

Hi Huw , how much mot is on it , if a few months its gotta be worth a secondhand pump or a cheapo pattern part one, you now know how quick and easy it is to change ,gotta be worth a try  .

More importantly how was the Indian takeaway , hopefully the split gunge from the pump wasn't too pungent .

Have a good one 👍🏽

Its got 11 months ticket on it, the thing is that I'm not entirely sure it is the pump. It was a bit grotty when I removed it, but the tank is clean as a whistle inside so can't see that its ingested more crud so quickly? Still no fault codes logged so I'm now back to square 1.

Its still for sale if anyone wants to take it on, price is negotiable but I've been offered £240 from cartakeback so thats the baseline. I hope that Silverlake will offer a bit more if I deliver it but money talks.

I'm reluctant to keep throwing parts at it with nothing conclusive suggesting what is actually wrong with it. Its a good car when its running, but my stress levels are off the chart and I just don't need another fucking millstone round my neck.

Indian was OK, I was full of hope as It'd been recommended as being 'superb food' by my in-laws, I went for one of the chefs specials to allow them to really wow me and it was just standard meat-chunks-with-onion-in-slightly-spicy-slop. Not bad, but just dull, considering. 

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Not at all.  But I think buried in there, the pumps might be similar enough.  We could bodge something just to check it out.

I'm with you that the best is to look at live data and try and work out what is going on though.

I also understand that you've had enough.  For me a car is a keeper, and I do whatever it takes, which with the simple junk I have isn't hard, or it isn't. 

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  • 2 weeks later...
2 hours ago, Tubbo said:

What’s the latest with the pocket rocket Sirion? @Stanky now you have fixed it all up it must be time to sell it back to me 😆

Sorry for the the confusion! Sirion is fine, runs perfectly and is providing solid backup while we look for a replacement for the Daewoo which has indeed been fragged. I did need to explain to Mrs_Stanky that it needed revs to make progress!

I'm trying to keep it away from salty roads as much as possible and have plans for cleaning and undersealing it with Dynax AB wax in the spring once it warms up a bit.

My brother is in the process of adjusting a stock exhaust to make it clear the back axle/ARB, which I hope will be ready by the end of the month. Ideally I'd like to get it a cat-back stainless exhaust with a slightly bigger bore but that's about £500 and I'm working to add to my diminished savings currently, and its not strictly critical. 

The clutch change has made a huge improvement!

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