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EdinburghJoe
V4 Fan

United Kingdom
127 Posts

Posted - 20 Dec 2020 :  19:06:17 Show Profile Reply with Quote
Evening,

I've got a Christmas question (well, it involves a coloured light, anyway).

I'm used to the way the oil pressure light behaves on my car (96v4) - it will go out after the first time I try to start the engine (I don't mean when the starter is actually running, I mean immediately afterward). The oil pressure generated just by the starter motor turning the engine over will be anough to keep it extinguished for a few seconds after I let go of the key. I notice this because I don't use the car often and it usually takes a few goes to get the fuel through and the engine to fire.

Now I notice that the oil pressure light comes back on immediately after I release the key each time. Once the engine catches it goes out and stays out, as it should.

Apart from what I've described everything else seems fine.

What's likely to have happened here? The car is low mileage (less than 40K), I've given it yearly oil changes (20w50, last change only a few weeks ago), and there is nothing much in the way of sludge inside the rocker covers so I think the engine must be pretty clean. I checked the oil level today, full of clean new oil.

Is it likely just to be the sensor, or more serious? I have what looks like a simple pressure switch - the wire goes into what looks like a large bolt under the fuel pump.

Any advice appreciated!

Thanks,

Joe

christophe
V4 Fan

France
118 Posts

Posted - 20 Dec 2020 :  19:52:59 Show Profile Reply with Quote
I have noticed such variations when switching from an oil filter brand to another one. This might have been the case during your last oil change. I use Mann filters without any problems. The reference is w916/1. This one has an anti drain back valve that might be missing from your current filter.
As long as your oil light stays out while the engine is running, I would not worry too much about that.
I hope this helps.
Nice evening to all.
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EdinburghJoe
V4 Fan

United Kingdom
127 Posts

Posted - 21 Dec 2020 :  18:07:53 Show Profile Reply with Quote
Hi Christophe,

That's a good point about the filter, though it is a Mann, same as the last one (I bought a batch of them together a couple of years ago)

I had a search around this site and found someone else with a similar problem to mine a while back - they took the pressure switch out and gave it a clean which fixed it so I might try that.

I also checked for play on the balance shaft (admittedly I'd not taken the fanbelt off) but I moved it around strongly enough to make the car move up and down and no play whatever laterally, though perhaps 0.5mm max in / out, so I hope that indicates no problem there.

Joe
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 21 Dec 2020 :  18:52:03 Show Profile Reply with Quote
Hey Joe, how are things across there in Edinburgh?
All quiet across here in Fife.
Had a bit of fun today - my 96 stopped briefly on the Queensferry crossing. Fuel staravation, fuel filter empty. It's a long standing issue I have, it comes, it goes. Very irritating, can't seem to get to the bottom of it.
Turned the key after a few seconds, and she was fine. A bit embarrasing though! Managed to get off the bridge before the Bridge Rescue folks arrived.
Anyway, your problem sounds to me like a switch problem.
One thing I would say.
If the car has not been run for a while, (week or two), I always take a cable off the coil, to prevent the engine starting, turn her over till I see oil pressure. (I've got an oil pressure guage).
If it's not been run for a very long time, ie months, I take the plugs out, and squirt some oil down the bores first, turn her over without plugs in, and only then try and start her.
Christphe is right about using an oil filter with a non return system incorporated.
Nothing so bad for an engine than being started "bone dry" of oil.
Don't skimp on oil filters.


1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 21 Dec 2020 18:55:14
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EdinburghJoe
V4 Fan

United Kingdom
127 Posts

Posted - 21 Dec 2020 :  19:13:27 Show Profile Reply with Quote
Hi Andy, nice to hear from you - that sounds like a pretty hairy experience on the bridge. I guess it's a long, fast run uphill to the crown of the bridge and that would have been sucking quite a lot of fuel.

Thanks for the advice, I think I'll buy a new switch (another poster here specified a Quinton Hazell XOPS2, and I can get one of them off ebay for juust over a tenner) - see how that goes.

After my car has stood for a week or so it NEVER starts first time, and I normally notice the oil light go out after the first crank, so I'm achieveing what you advise anyway! Or at least I was, up until yesterday, hence the post.

Joe
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 21 Dec 2020 :  20:10:11 Show Profile Reply with Quote
Joe
I was just below the crest of the bridge, going north. If I'd been over the crest I could have freewheeled down the other side.
At least there's a hard shoulder on the new bridge, the old one doesn't have a hard shoulder.
To try and fix my problem I've recently fitted a new Quinton Hazel fuel pump, and fuel filter.
The tank was out a couple of months ago, and was clean as a whistle, so I'm stumped!

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 21 Dec 2020 20:11:57
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Gavinc
V4 Fan

United Kingdom
103 Posts

Posted - 21 Dec 2020 :  23:28:31 Show Profile Reply with Quote
Hi Andy, had a very similar problem with my latest 99 which had been standing for a while before I collected it. Intermittent fuel loss, tried everything, new pump, filters, tank cleaned. Eventually I put an air hose onto the fuel lines and you would not believe the crud that came out of it. Has run faultlessly since!

96V4 stage rally car
99 stage rally car.
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 22 Dec 2020 :  18:17:28 Show Profile Reply with Quote
Gavin.
I was actually thinking of doing that. Problem is, though I have a pretty well kitted out garage, I don't have a compressor.
Might try and Heath Robinson something together with my eletric tyre pump.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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UK_Sub
V4 Guru

United Kingdom
2317 Posts

Posted - 23 Dec 2020 :  09:56:24 Show Profile Reply with Quote
Not sure that will have enough a prolonged puff to blow down the fuel line. I was thinking you could use the air from a pumped up spare tyre somehow?
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chris steeden
V4 Fan

United Kingdom
147 Posts

Posted - 23 Dec 2020 :  12:36:17 Show Profile Reply with Quote
Reply to Andy's problem of fuel starvation. I had a word with a friend and he told me of a simular problem he had with his 96. His was/is a 2 stroke model but my friend believes that the fuel tank may be simular. He also commented that if your Saab has the same fault then blowing back through the fuel lines will only be a temporary cure as rust will reform inside a section of the tank and block the feed flow. He suggests that you disconnect the pump and check the fuel for minute particles of rust. This should also show on your carb filter, if fitted.

http://saab-v4.co.uk/speedball/topic.asp?TOPIC_ID=2804

Edited by - chris steeden on 23 Dec 2020 12:40:08
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 23 Dec 2020 :  19:34:33 Show Profile Reply with Quote
Thanks for your inputs Simon and Chris.

Simon. Ah yes, a blown up tyre would have a large reserve.....I'll try it.

Chris.
My tank is very clean inside, I had it out recently. Swished it out with petrol, and inspected the inside with an Endoscope, so I don't think there are any issues with the tank. Gavin's idea that it might be the fuel line is the last things for me to check. The Pump and filter are new, just fitted, but still it stopped in the middle of the Queensferry Crossing (A very large cables tension briddge near Edinburgh)

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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christophe
V4 Fan

France
118 Posts

Posted - 23 Dec 2020 :  21:48:16 Show Profile Reply with Quote
There might be some rust pinholes in your fuel line. You can check this with a vacuum pump after blocking one end of the line. If the line can't hold the vacuum, you've got your answer. Of course, your rubber fuel hoses must be in top shape and preferably hold by clamps.
If the trouble appear mainly when the tank is almost empty, I would say that the problem comes from the fuel pickup line inside the tank.
Nice evening to all.
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chris steeden
V4 Fan

United Kingdom
147 Posts

Posted - 24 Dec 2020 :  10:16:54 Show Profile Reply with Quote
Hi Andy, if I understand my friend right what he was saying is that the rust blockage wasn't in most of the tank but isolated inside a little chamber shown in his pictures. I believe that you can't see inside this chamber with a scope and that is why he cut a hole in it. Have a look at the picture and you can see the feed pipe entering this chamber. I believe that he said rust particles was inside and had built up to the 'draw-off' level of the feed pipe thus causing intermediate blocking and fuel starvation. I do accept that this problem was on his 2 stroke and that your tank internals might be different. Can you see with your scope as viewed through the fuel gauge sender hole whether or not you have this chamber fitted? It could be a red herring so sorry if it is. Great Christmas everyone.

Hi Christphe, I was wondering, wouldn't you smell petrol if there was a pin-hole leak? It would have to be a large hole/prick in the pipework to overcome the pull of the pump. Maybe not, I'm not an engineer. Wishing you and your loved ones a Happy Christmas & a Great New Year.

Edited by - chris steeden on 24 Dec 2020 10:17:47
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 24 Dec 2020 :  11:13:53 Show Profile Reply with Quote
Chris
Interesting story about the stroker tank.
When I had the tank out in the summer, I swilled it out 2 or 3 times with a bit of fresh petrol. Not a drop of any sort of sediment came out. No sediment came out of the drain plug, when I drained the tank prior to removing it.
I know, having spoken to a previous owner of the car, (who owned it for 15 years), that he had the tank cleaned out professionally at some point in time. That may be 10 or 15 years ago now of course.
Doesn't mean that there's no crud trapped in that wee box, but the chances are low.
I'll flush the fuel line in both direction, to see what comes out. If it's clean as well, I might try running a new rubber pipe from back to front for a while, to see if that helps.
Problem is of course it is a very intermittent problem. Until it happened again a few weeks ago, and last week, I hadn't had the issue for a couple of years.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 24 Dec 2020 11:14:54
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Derek
V4 Guru

United Kingdom
2036 Posts

Posted - 24 Dec 2020 :  11:34:14 Show Profile Reply with Quote
I don't know, but I suspect that QH haven't made fuel pumps for the 96. Ford V4 for many many years. An NOS pump getting it's first taste of ethanol may have had the diaphragm curling up in disgust. That's a bit dramatic but a bad diaphragm gets to be very inefficient. A long hill may mean it can't keep the float chamber full. Been there had that. Down the other side, no problem. Difficult to test other than by replacement. Many have gone electric and you could consider that option. As you say, the pipe might be blocked so worth blowing that through. Check the length of the fuel pump push rod. If it's fitted the wrong way round the non hardened end wears, it gets shorter, and doesn't work the diaphragm enough. Search here for rod lengths. It has been covered a few times.
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andydeans3
V4 Guru

United Kingdom
1517 Posts

Posted - 24 Dec 2020 :  14:28:34 Show Profile Reply with Quote
Derek
Thanks for your thoughts.
The pump was certainly listed as being for the SAAB V4, and other Ford V4 engines.
I was EXTREMELY careful to put the rod back the same way it came out.
It was quite clear which end was which. The end that goes in against the camshaft had a blue hue. Hardening process?
The new pump certainly looked to me identical to the one that came out.
I did not measure the length of the rod though, I'll search the forum for the info.

I do actually have an electric pump already fitted under the rear seat, with wiring run up to the fusebox. Fitted it years ago, prior to a continental tour as a "Belts and braces" approach for the long tour to Sweden and back.
I suppose I should try plumbing it in and connecting it at the fuse box.
If the fuel line looks clean, I think that'll be my next move.

Merry Christmas to all, and let us hope that 2021 is beter than 2020 has been!

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 24 Dec 2020 14:39:18
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