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Old 26-03-2012   #1
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Unhappy Misfire after water pump change


Can someone help me please?

I changed the water pump on my í83 X1/9 yesterday. The jobwent as expected; cut knuckles and lots of swearing as usual.

I took the car for a pleasant drive over the mountain roadsto enjoy the seldom-seen sunshine. Everything was fine for about 30 miles whensuddenly the car developed a misfire. The temperature gauge was readingperfectly normal, and the car had not lost any water.

Driving the car home it began to misfire very badly. Theengine cut out twice in heavy traffic and struggled to start. Almost as soon asthe misfire started it cleared up.

I have checked the plugs, and I have changed the plugs, butthe misfire is still evident. I have changed the HT leads, but the engine stillmisfires. A friend has used a compression tester and everything appears to befine. I have checked the leads to the Lumenition electronic ignition andeverything is fine. I canít see any leads hanging off. The engine isnít losingany water; it starts fine; and it doesnít feel down on power; yet it still hasthis misfire.

I have got a spare coil; but I have mislaid it. Could theproblem be down to the coil?

I hope itís not the head gasket?

Thanks.
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Old 26-03-2012   #2
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Re: Misfire after water pump change

Check your fuelling - the problem may have nothing to do with the water pump or the electrics (although it does sound like an electrical fault). A loose adjustment screw will cause all sorts of problems as the screw winds itself in and out. It is unlikely to be evident at revs though, only at idle.

If it happens under load then get the jets checked and cleaned (one at a time).
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Old 26-03-2012   #3
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Re: Misfire after water pump change

Thanks Jimbro1000.
I checked the adjustment screw and it did make the car run much better, but the misfire is still evident.
I have cleaned the jets again and have cleaned the little gauze filter inside the carb. There was a little bit of muck in there. At one point this evening the misfire vanished, but the engine died soon after; upon restarting the engine the misfire was back.
Otherwise the car is driving fine and still pulls strongly. I just wish it didn't sound like a Subaru/ Beetle.
What else can I try? I'm still thinking of buying a new coil?
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Old 27-03-2012   #4
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Re: Misfire after water pump change

Without putting the car through diagnostics we can only guess if the coil is breaking down. Swapping it out would certainly eliminate it from the equation but it can be an expensive method of diagnosis (and assumes the new coil actually works in the first place - a reasonable assumption but not always correct).

The best option there would be to borrow a coil from a known working car but if you don't have a friendly X1/9 owner anywhere near you that isn't exactly convenient.

Getting back to potentially cheaper diagnostics, does it still misfire without load (ie just revving it in neutral)? If so you can buy a cheap set of spark plug caps that will flash with each spark (they sit between the plug and the lead). A set of these would quickly establish if the ignition system is at fault.

You can just inspect the plugs themselves and make sure they are showing a clean burn (light tan coating to the electrode). The usual diagnostics apply (I wrote an FAQ for the owners club about 13-14 years ago that should still be around that has all this in btw, I donated the same here but it has not been published that I know of). Any damage to the plugs should be corrected by simply replacing them but could mean the engine is running dangerously lean. A black sooty coating means you're running rich while a wet coating could mean oil is getting in or the fuel is not getting burned both of which are bad but you can normally spot the oil from the exhaust showing blue smoke. If the plugs are showing some misbehaviour it could be the float chamber in your carb has problems - the floats need to keep the fuel at a set level otherwise the fuel-air emulsion through the jets will be all wrong, too low will result in a lean burn while too high will result in a rich burn regardless of the jet sizes and cleanliness.

A compression test is always useful but you've already done that so we can assume that the rings are intact, the gasket safe and the valves are seating ok.

One thing that is worth checking is the inside of the distributor cap - make sure the "eye" on the lumenition parts is clean and clear as debris here can play merry havoc with your ignition. You also want to check the cap is not cracked or showing signs of tracking between contacts, the arm is worth a check too. (You can't believe how glad I am that none of my cars uses a distributor).
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Last edited by jimbro1000; 27-03-2012 at 10:06.
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Old 27-03-2012   #5
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Re: Misfire after water pump change

Thanks for the help Jimbro1000.

I've got a spare rotor arm lying around; I'll change it when I get home. I changed the distributor cap last night. I have noticed that the distributor cap is a pain in the neck to fit correctly.
The spark plugs appeared to be healthy. When I checked them they were all golden brown. They were not wet or black. I cleaned them up anyway and gapped them to 0.7.
The misfire does seem to be more evident at idle and low RPM. When driving in traffic, i.e. light throttle the misfire seems more pronounced. Under load the misfire can't be detected. Likewise; when the engine is revved whilst not under load the misfire seems to vanish.
I will check the Lumenition wiring, the optical sensor, the distributor cap, change the rotor arm, check the plugs again, check the jets and the float and report back on here.
Thanks for your help.
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Old 27-03-2012   #6
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Re: Misfire after water pump change

I don't know if this will help but check the positive power feed that powers the ignition system
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Old 27-03-2012   #7
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Re: Misfire after water pump change

Quote Originally Posted by lancepbul View Post
I don't know if this will help but check the positive power feed that powers the ignition system
Thanks for the advice both. I checked the power feed to the ignition system and it is okay.
I've taken a look at the distributor cap and rotor arm etc and everything seems to be fine.
I did have a problem however when I went to start the engine; nothing was happening. After a bit of head scratching I finally found a lead had dropped off the starter motor.
With the lead back on correctly the engine started fine and had no misfire. By the time I jumped in the car to drive to the nearest Tesco the misfire had returned.
The misfire is only evident al idle. However, when under load, especially on the long steep hill near home, I can hear a 'ticking' noise from the engine.
Any ideas?

Friends and family are urging me to get rid of this car! It seems to be one problem after another! Surely these FIAT's aren't all this bad?
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Old 28-03-2012   #8
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Re: Misfire after water pump change

The ticking could be pre-det or it could be an HT lead breaking down, both would act as a misfire.

If it only does it at idle or low speeds and only once it is warmed up I would consider looking at the inlet manifold as well and make sure it is all tightened up correctly and failing that it is a good idea to check the gaskets too.

The problem you have first and foremost is that it is an old car, nothing will work exactly the way it was supposed to and a fair amount of maintenance is needed, especially compared with a modern car (still much, much better than older generations of car).
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Old 28-03-2012   #9
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Re: Misfire after water pump change

I was planning on checking the inlet manifold and the carb gasket tomorrow. And I was going to retard the timing slightly to see if the ticking noise vanished.

Unfortunately, the car died several times tonight on a very short drive. After checking the jets and fuel delivery etc. it looks like the fuel pump is knackered.
However, that isn't the worst part of the story. With the engine idling I noticed a small cloud of steam. I looked a little closer and spotted a small water leak from the head.
So much for the compression test! My worst fears have been confirmed; the head gasket has gone!

Thank you for the advice folks. It's nice to know there are enthusiasts out there willing to help.

No doubt I'll be back soon with another problem.

Thanks,

Tony
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Old 28-03-2012   #10
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Re: Misfire after water pump change

I've been told to stop worrying too much about the car!
According to a friend, it could be a leak on the inlet manifold? He went in to depth about water seeping in to a cylinder and causing a misfire. He did explain why the misfire goes away when the engine is revved. I can't remember the exact details, but it seemed to make sense!
I guess I'll have to investigate on Friday.
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Old 29-03-2012   #11
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Re: Misfire after water pump change

A manifold leak would make a lot of sense, as would a fuel pump failure. Remember what I said about classic cars taking a lot of patience and care?
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Old 29-03-2012   #12
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Re: Misfire after water pump change

Quote Originally Posted by jimbro1000 View Post
Remember what I said about classic cars taking a lot of patience and care?
Where's the fun in a car that starts first time every time and doesn't have some kind of start-up ceremony every time?

I'll change the fuel pump and take a look at the manifold tomorrow and let you know the results.
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Old 29-03-2012   #13
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Re: Misfire after water pump change

If the manifold is loose you would hear a ticking from the exhaust manifold, typically you only hear that sort of thing when the manifold is cracked but if one (or more) of the studs has come loose it would have the same effect.

I know the leak is from the inlet manifold but they share studs so generally if one is loose, so is the other.

One word of warning, do not be tempted to disconnect the exhaust pipe from the manifold. I absolutely guarantee that the studs will bend or snap and that it won't go back on cleanly. I was so sick and tired of this on my cars that I ditched the stock manifold, you may of course be lucky but personally I would rather play russian roulette with a fully loaded revolver, the odds of coming through unscathed are slightly better...

The studs from the head seem to be more durable but care still needs to be taken - you can still buy the studs from Fiat if need be (absolute worst case of course).

The fuel pump on the other hand is dead easy provided you don't misplace the actuation rod that follows the cam. I don't know if the pumps are supplied complete or just the diaphragm but either way it is one of the easier jobs.
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Old 31-03-2012   #14
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Re: Misfire after water pump change

Last night a friend and I had a look at the car again.
After changing the fuel pump we took a look at the plugs. Three of them were golden brown as they should be; but the fourth was covered in black soot. The plug wasn't wet. The last time I checked the plugs they were all golden brown.
With the engine running we removed the plug leads one at a time. No. 1 didn't make much of a difference. No. 2; the engine almost died. No. 3; the engine almost died. No. 4; there was no difference at all.
We checked the HT lead and the plug and they were fine. We tried different leads and plugs but it made no difference.
We couldn't do a compression test last night as my tester is broken; I'll have to wait until Monday to test it.
Any thoughts? I'm wondering if I have a valve problem? Or is it still down to the inlet manifold?
Thanks
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Old 31-03-2012   #15
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Re: Misfire after water pump change

Hi ,
I've just read your thread..,

Valves..?? unlikely as there was steam / mist evident,

has the car been losing coolant - in the last week..?? Why did you change the pump - overheating before..??

the failing fuel pump is a possibility,
but when mine have failed it would grind to a halt , then fire again almost instantly, NOT a prolonged misfire...,


I take it you've looked under the bonnet in the DARK looking for arcing from plugs/leads/dist..??,

It's possible you've got a couple of things wrong / failing,
but getting the 2 cylinders firing is the 1st port of call,
Charlie
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Last edited by varesecrazy; 31-03-2012 at 17:21.
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