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Jeremy
Net Member

United Kingdom
3 Posts

Posted - 08 Feb 2017 :  22:37:33  Show Profile  Reply with Quote
Hi All. I have a 1500cc engine that misfires then dies until it cools down then fires back up with out a problem.

Iíve changed everything and back again, Iíve forgotten where i have got to. Iím all out of ideas! Has anybody got any new ones?

The engine race prepared, is dry sumped with external mechanical oil pump and has an electric fuel pump. Its running with pertronix ignition module in the distributer and a flame thrower coil.

Out on the road it lasts about 20mins misfires, starts with a small one then gradually gets worse and then the engine will eventually die. Let it cool down then will start no problem.

Then when running in the workshop with a fan blowing in the rad and oil cooler to keep it at work temp and blipping the rpm to 2500 then gradually raise it to 4500 and drop down to tick over it will either:-

Run, then turn it off and it wonít restart until it has cooled down.

Or last about 40mins before the revs die and wonít pick up then the engine will cut out. Again it wonít restart until it has cooled down.

I have:-
Changed the ignition back to the original points system and back to the electronic ignition.
Renewed the fuel pump.
Serviced the carb, I have a constant 3 psi fuel pressure.
Cleaned out the oil pipes from the pump to the cooler, changed the oil.
Compression is good.

Water Temp is constant at 90#8451;
Oil Temp gets up to 80#8451;
Oil pressure is at 55 psi drops to 30 on tick over when then oil temp goes up to 60 #8451;. the pressure will pick up again to 55 psi when I raise the rpm to 4500.

I have noticed a fluctuation of the revs on tick over of about 200 rpm. the engine revs also fall on tick over as it gets hotter also about 200 rpm.

Could there be an issue with the head, either carbon build up or head gasket problems. I was advised, (while waiting for recovery) that the clearance on the tappets may be to tight. Checked this out with the cam spec and they seem okay.

Any Ideas?

anonymous1
Forum Addict

5863 Posts

Posted - 09 Feb 2017 :  08:47:04  Show Profile  Reply with Quote
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julian
Forum Admin

United Kingdom
3730 Posts

Posted - 09 Feb 2017 :  09:48:55  Show Profile  Visit julian's Homepage  Click to see julian's MSN Messenger address  Reply with Quote
Hi Jeremy - good to hear from you again!

I assume this is for your prod-spec exxy I last saw you with...

Another thought to the problem - it sounds suspiciously like you are loosing vacuum through the carb when it warms up - which means it starts running extremely lean. It is normally down to heat related distortion in the carburetor (or manifold) major castings and/or a damaged gasket.

Another major mechanical problem on these engines (the exxy 1500 in particular -possibly due to the nature of the engine bay) is distortion of the block along the crank line - for most people this is experienced as an inability to start when hot but if the distortion is significant it will feel like the engine is starting to seize as it heats up. When cold every thing appears to be absolutely fine (or within tolerance) which can make it a nightmare to diagnose. I'm sorry to say there isn't really a cure for this one except for replacing the block itself.

When we built up the engine for my exxy we went through 12 different blocks before finding one that didn't distort (using the later Punto GT3 block). The process was to heat them up in a kiln and measure the crank alignment while it was still hot. Not exactly practical for an engine in-place but worth keeping in mind if the block does need swapping.

I will ask around my contacts and see if anyone has any more ideas.

2009 Abarth 500
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Jeremy
Net Member

United Kingdom
3 Posts

Posted - 09 Feb 2017 :  23:27:57  Show Profile  Reply with Quote
Thanks guys for the quick response!
Julian, It is the prod spec exxy. I'm trying to get it back on the track!! I have renewed the gaskets on the inlet manifold (head and carb). I'll try replacing the manifold itself and i have a spare carb body that I'll swap.
When I do try to restart it after it has stopped it turns over fine no sign of seizing.
Andy; I shall check the electrics (again) and also the fuel system. I am running it with a filter. I do have foam in the fuel tank, so I'll have a look at that. There is no sign of contamination in either the oil or the water.
I'll let you know how I get on. Might be a few weeks as its getting a bit chilly again!
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anonymous1
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5863 Posts

Posted - 10 Feb 2017 :  05:51:49  Show Profile  Reply with Quote
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Martin
Administrator

United Kingdom
7828 Posts

Posted - 25 Mar 2017 :  20:24:16  Show Profile  Visit Martin's Homepage  Reply with Quote
Jeremy. if you haven't solved it yet, can I remind you that this engine suffered from fuel starvation from the fuel tank vent closing and sticking shut, and a vacuum pipe leakage to the dissie vacuum advance, and an air lock from the carb fuel piplng (probably due to manifold heating causing vapourisation).

There is another possibility - given the time since its last known rebuild (here)... three to four years is about the time before a high pressure engine's head gasket shows signs of de-lamination.

Good to hear from you again! And good luck

Martin
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Jeremy
Net Member

United Kingdom
3 Posts

Posted - 17 Apr 2017 :  21:28:12  Show Profile  Reply with Quote
Hi guys

Iíve managed to get some time to have a look at the engine. I warmed it up to working temp again and checked the electrics, that all seemed fine. (Still have a spark when I try and restart it.)

Martin I remembered the fuel tank issue so have cleaned the fuel system from top to bottom. I have no vacuum advance on the dissie, and I removed the let fuel pipe at the carb to check that I had fuel pump in to the carb when I try and re start and that was fine.

Let it cool down warmed it up etc etc. Took the carb lid off and noticed a Ďhissí sound. Sucking in air. Iím now giving the carb a clean up. I also took the exhaust manifold off and noticed some carbon deposits in the head. So took the head off. It is really badly coked up!

Do any of you know where I can get a decent head gasket?

Cheers

Jeremy
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julian
Forum Admin

United Kingdom
3730 Posts

Posted - 18 Apr 2017 :  09:49:32  Show Profile  Visit julian's Homepage  Click to see julian's MSN Messenger address  Reply with Quote
You can get Spesso gaskets from Trevor Nicosia http://www.nyssaracing.com/shop/spesso/fiatx19.php

2009 Abarth 500
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