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andy b

what to expect of the turbo

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I am about to run the turbo after it has been off the road since 02 i bought it of ebay about 3 years ago

I have now finished it cosmetics and cam belt got all the electrics working just a recommission job.

I will give it  a gentle run for 50 mile or so and then try it out what can i expect to see on the boost gauge and when should the dump valve operate ect ect.

andy b 

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Maximum of about 8 psi balls out...then the wastegate should open and maintain that boost figure. If the diaphragm has got a hole in it or the valve is stuck in the valve guide, you will see the boost figure climbing higher....DON'T LET IT...!!! back off straight away and get the wastegate mended. Too much boost is the easy way to wreck a 910. If the spring in the wastegate has weakened over the years, then you might get a lower figure for the wastegate opening...mine gives 6 psi these days, and I'm happy with that as it's quite fast enough and, at 6psi max. boost, pretty bombproof. The operating figure is set by the internal spring and the thickness of the alloy spacers on the wastegate...thinner ones give more spring compression and thus more boost. One could modify the wastegate to be adjustable, with an internal spring seat moving up and down by a threaded adjuster going through the hole in the bottom...you'd need another hole for venting purposes...but I think it could be done. Thought about it but didn't bother!

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John thanks for that can't wait to run it as the NA is now also finished after the repaint i have not driven an Esprit for at least 4 years. But the turbo is to be run first.

andy b

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I am in the same position, just finishing troubleshooting a problem which put this car (82 turbo) off the road and ended up with me buying it to fix. I have narrowed down the problem to either the fuel pressure regulator or carb needle valves or (unlikely) fuel pump. I have parts on order and will then be road testing. From past experience I am almost expecting the wastegate to stick.

 

Small detail, in your post you mention the dump valve. This part (mounted under the pressure regulator on the side of the plenum)  is never any issue.The wastegate is the troublesome part.

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The dump valve is there to protect the turbo against any backfire. Superchargers have them too...on my old MG TC it was called the Explosion Valve!! As Andrew says, you can forget about it causing any problems.

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andyww

what are your symptoms with the motor.

Mine when i bought it was running on 2 cyl  i took the carbs off and cleared the jets i have not got around to the fuel pressure regulator yet until it is on the road. also i had very low compression on all cylinders which have now come up with running the engine   

and should be fine for a 48000 mile car when run on the road for a while. I suspect the rings were stuck.

with the box of bits is another fuel pressure regulator so i think the former owner was at his wits end and gave up put the car on ebay with a sell it now price which i could not resist.

 

carb needle valves? when do they come into play

andy b 

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I thought I had found the problem before, because someone had fitted a lightweight starter which didnt have the auxiliary contact so they wired out the ballast resistor permanently. The coil was overheating. This tied up with the previous owners report of sudden cutting out and no start for the next 15 mins or so.

 

But having run the engine in the garage I am finding the float chambers are emptying. I am sure the pump is working properly, because removing the return pipe from the regulator and running into a jar there is plenty of flow. So the conclusion must be either the regulator is not allowing enough fuel into the carbs and diverting it all into the return pipe or there is one or two stuck needle valves. 

 

When I had the carb lids on the bench I think I saw one of them stick closed when I lowered the float. The symptoms mean both would have to be sticky though so the regulator appears to be the prime suspect. It doesnt quite tie up with the POs symptoms though because its unlilkely both float chambers would run empty at exactly the same time but there is definitely a problem there.

 

I did a compression test and one cyl was down at 30 (!) but when I re-tested after running and hot, they were all around 110 which is not brilliant but OK for a 75K mile engine. The early turbos are low compression engines.

 

What you could do on yours if you suspect a fuel problem on 2 adjacent cyl is remove the intake plenum cover and duct from the turbo and run it as mine currently is, with the carb intakes exposed, then you can easily remove the carb lids as a pair. be careful not to tear the gaskets but new ones are available from SJ. Check if both float chambers are full. You will need a new plenum and crossover pipe gasket anyway. If you undo the regulator from the plenum the whole assembly of both lids and regulator can be lifted off without having to disconnect any fuel lines.

 

If one chamber is empty replace the needle valve and seat. Or just replace both anyway. These are located in the lids of the carbs and operated by the floats. If both are empty maybe there is a problem with the regulator. 

 

Sounds like you got a good deal on the car as this should not be a difficult problem to fix, not much it can be. 

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andyww

I would be surprised if the needle valves are sticking as the fuel pressure will push them open i have had the floats jamming  on the side walls of the carb body. it will fill with fuel then jam with the needle valve closed.

ps did you have the throttle fully open when you did the compression test if not re do it with them fully open

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If the car has been left for any length of time, then the varnish resuting from the evaporation of modern petrol can stick almost anything. I have had the needle valve on my boat carburettor stick solid despite full pressure from the fuel pump...so your needle valves could be sticking. As has been said, physically check that the float chambers are staying full to the same amount on each carb. Andy's right about compression tests...all the plugs out, and full throttle for the test...let it wind over on the starter a dozen or so times to get the final reading. Plenum chamber gaskets can be cut from thin cork wall tiles, if you don't want to wait for a delivery or you're just a cheapskate like me.....

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I am in the same position, just finishing troubleshooting a problem which put this car (82 turbo) off the road and ended up with me buying it to fix. I have narrowed down the problem to either the fuel pressure regulator or carb needle valves or (unlikely) fuel pump. I have parts on order and will then be road testing. From past experience I am almost expecting the wastegate to stick.

 

 

This problem was the pressure regulator. I took it apart and there is a diapragm inside which has 2 layers, it had leaked and become inflated like a balloon. Replaced with a new unit from SJ.  

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magor area

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andywww

How are you going to set the pressure is it by trial and error as it could go lean under full load ???

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andywww

How are you going to set the pressure is it by trial and error as it could go lean under full load ???

 

Hmm I had not thought about adjusting it from the setting supplied. Maybe I should check with SJ about this?

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let us know what they say could be interesting.I was expecting to adjust mine say run the car fast and shut off coast into a lay-by

and pop a plug out and have a look other than that it is a rolling road really don't want to melt a piston. may be we should start a new topic on it see what the forum has to say.

 

andy b

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I just use a simple T piece from the plenum feed and a pressure gauge, then use a long enough hose to tape the pressure gauge to the boot window.  Then you can check it dynamically under boost conditions.  boost pressure +4psi - its a doddle! 

 

I also do regular plug chops too!

Edited by 910Esprit

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I spoke to SJ.

 

They said proper procedure is to adjust to 4 PSI fuel pressure at idle.

 

I suppose checking under boost provides an extra check that its working properly and very worthwhile.

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cool chaps thanks for the info

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I just use a simple T piece from the plenum feed and a pressure gauge, then use a long enough hose to tape the pressure gauge to the boot window.  Then you can check it dynamically under boost conditions.  boost pressure +4psi - its a doddle! 

 

I also do regular plug chops too!

 

What kind of gauge do you use? I tried to use my K-Jet pressure test gauge but its range is too high and doesnt give any reading at all.

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Compound gauge, 10psi range on pressure.  Cant remember where it came from, but I'm sure there must be something similar on ebay

 

pressure.jpg

 

Job done - http://www.ebay.co.uk/itm/Fuel-Pressure-Gauge-Kit-15-psi-0-1Barg-With-Jubilees-/181554225331?pt=LH_DefaultDomain_3&hash=item2a4579a0b3

Edited by 910Esprit

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Can't remember forgive me if i am talking rubbish the turbo is on the ramp so can't take a look is the plenum or turbo pressure connected to the fuel pressure regulator if so does it auto adjust the pressure to the diaphragm thus allowing more fuel at boost?

After initial 4psi setting. 

andy b

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The fuel pressure regulator connects to the aluminium pipe from the turbo...it's part of the hose system that links the carb. tops and applies the pressure to the carbs as well. Keeps the fuel pressure regulator at 3.5psi above the intake pressure, according to the book.

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It went well so good in fact the mot man took it out for a spin i took it up to 5psi on the boost gauge when i changed gear i think i heard the wast gate operate. for the first run to mot stn that was enough. as yoda would say "pleased with it i am"

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