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| Seems to be electrical... or not? https://www.ausmini.com/forums/viewtopic.php?f=2&t=94734 |
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| Author: | mini_man_90 [ Fri Jan 27, 2017 7:55 am ] |
| Post subject: | Seems to be electrical... or not? |
Among many problems I'm having at the moment, my fuel pump and thermo fan don't seem to be consistently cutting in while my car is idling... the thermo fan cuts in once the ignition is off to cool the engine down, as it's wired to do, but not while idling. If i blip the accelerator a few times the fuel pump (facet type) starts blasting away and the thermo will kick in (provided it's at temp). Checked atlternator at idle with multimeter and it looks like it's charging okay. Volt gauge takes its time to climb one engine is running but, after a minute or so, sits at 13.5V okay as well. Everything is running through relays, have swapped them around and no difference. Battery has charge, alternator belts not slipping... what am I missing?!! Engine also has a miss on cylinder 4, but seems to have decent spark across all 4 plugs and leads when earthed out and doing visual inspection... Miss may be a/f related, but I feel there's some electrical gremlins causing a riot in my engine bay! |
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| Author: | simon k [ Fri Jan 27, 2017 8:30 am ] |
| Post subject: | Re: Seems to be electrical... or not? |
once the alternator is spinning, it should be pumping out the 13.5-14 volts straight away... so either the voltage gauge you have is dodgy or the alternator is doing something odd blipping the throttle while idling to get the fuel pump and fan to start up makes it sound like there's not enough amps available in the system a miss on cylinder 4 shouldn't be a/f related, as cylinder 3 (dunno what carbs you have) should be the same. I'd be reluctant to blame that on the same thing that's giving you a problem with fuel pump & fan. what's your idle speed? bump it up to 1300-1400rpm and see what happens to all of your symptoms I reckon your alternator isn't putting out enough juice |
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| Author: | mini_man_90 [ Fri Jan 27, 2017 8:40 am ] |
| Post subject: | Re: Seems to be electrical... or not? |
Running twin webers, so cylinder 3 should have same symptoms as 4 if it's a/f. Interestingly enough, it did have the same issue initially, but then seemed to get slightly better, only leaving cylinder 4 with a definite miss. Pulling leads off 1 and 2 drop the idle about 500rpm, cylinder 3 is not quite as much, but cylinder 4 only changes idle by 100rpm or less. It looks more like the needle just vibrating a little. When you put the lead back on, there is an audible difference, but not when you remove it when compared to the other cylinders. Idle speed is 1100ish, and I think when it's idling a bit higher everything does seem to be a little better behaved, but I was thinking bad alternator too... just seemed weird that the multimeter read it as 13.5-14 as soon as the engine was on, but the gauge doesn't. Might try another multimeter and compare results. |
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| Author: | Irish Yobbo [ Fri Jan 27, 2017 1:36 pm ] |
| Post subject: | Re: Seems to be electrical... or not? |
> just seemed weird that the multimeter read it as 13.5-14 as soon as the engine was on, but the gauge doesn't. That's actually pretty normal, especially for an old volt gauge. Unlike a speedometer or tachometer the voltmeter generally doesn't need to react to changes very fast, so it's probably quite dampered in the same way that a temperature gauge or fuel gauge is dampered. |
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| Author: | mini_man_90 [ Fri Jan 27, 2017 5:15 pm ] |
| Post subject: | Re: Seems to be electrical... or not? |
So we have hopefully found a major culprit today! Engine timing was perfect, hooked up timing light to check distributor timing and found that there was weak and inconsistent signal on all leads with timing light. No signal at all in some instances. There's play in the shaft that we had originally put down to being advance movement, but now we're thinking is actually the cause of our issues. Ordered up a new distributor with electronic module to throw in it next week. |
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| Author: | Convertible Mini [ Sat Jan 28, 2017 1:45 pm ] |
| Post subject: | Re: Seems to be electrical... or not? |
I would suggest trying a known good Points distributor to see if it is the culprit. |
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| Author: | drmini in aust [ Sat Jan 28, 2017 1:55 pm ] |
| Post subject: | Re: Seems to be electrical... or not? |
Unless it has new plug leads I would check their resistance. Old leads have a graphited string core, when they age their resistance goes up. I would bin them if over 5K ohms. |
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| Author: | mini_man_90 [ Sat Jan 28, 2017 1:58 pm ] |
| Post subject: | Re: Seems to be electrical... or not? |
Leads are only about 4 years old. Bought a good new set of leads when I first bought the car while going over basic serviceable things. We have a spare set that we've been interchanging which hasn't been making any difference. |
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