Hi,
can anybody tell me if there's an issue with polarity on fuel pumps. After a series of fuel starvation problems on my '54 serII, I've fitted temporarily, a new fuel pump labeled AUC 66 as part of an elimination process. I was lent this pump and it was brand new in an SU box and came from our local branch spares and had never been used
Now the pump worked ok for a while, but then it stopped pumping(I could see this through the in line filter) and when I touched it the body, was screaming HOT and I mean HOT!
The only thing I could think of is that the pump is for a later model possibly with reversed polarity.
Where later model's polarity changed or can someone shed light on this?
Regards
Dawpooldad
Fuel pump polarity
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dawpooldad
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- Location: Wirral
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Re: Fuel pump polarity
The normal points pumps are not polarity sensitive...... If it had been used on -ve earth and you are now using it on +ve earth then the points will need cleaning and re-gaping. This what you should do now anyway...... But if you have any filters in the fuel system - get rid of them ! Not necessary. Can't find an AUC 66 anywhere - are you sure?? There is an AUA 66..........
Re: Fuel pump polarity
There have been at least three methods of suppressing sparking at SU points, one of which, the simple diode, was polarity sensitive. Burlen have this information somewhere deeply hidden in their obscure, confusing, and often-contradictory website.
But if it's the pump body that's hot, I doubt if this is the problem, unless it, or some other factor, has led to the points staying closed. Given that the pump normally spends most of its time passively pushing fuel out, with no current flowing through its coil, and only intermittently and briefly uses electrical power to suck in fuel and compress its spring, it might well overheat if current was flowing all the time.
When power is applied to the pump, does the inner bit, that the points screw onto, twitch at all? If so, do the points then open?
Kevin
But if it's the pump body that's hot, I doubt if this is the problem, unless it, or some other factor, has led to the points staying closed. Given that the pump normally spends most of its time passively pushing fuel out, with no current flowing through its coil, and only intermittently and briefly uses electrical power to suck in fuel and compress its spring, it might well overheat if current was flowing all the time.
When power is applied to the pump, does the inner bit, that the points screw onto, twitch at all? If so, do the points then open?
Kevin
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dawpooldad
- Minor Friendly
- Posts: 34
- Joined: Wed Apr 17, 2002 1:00 am
- Location: Wirral
- MMOC Member: Yes
Re: Fuel pump polarity
Hi,
thanks for the replies.
I've not dismantled the pump to check, as it is a new pump effectively on loan from the local club.
When it cools down though, it pumps just as it should, but then starts to get hot again and eventually stops. I guess that I will only find out if I remove the cover to check.
Regarding suppression, I thought that SU used a capacitorfor this. A thought just occurred, if it's electrolytic or tantalum then that could be the problem in the absence of polarity instructions from Burlem.
As to the the inline filter, it is there for me to check the fuel flow wrt the fuel starvation problem. Is there an issue with these units?
I've used them before on this car without any probs although a proper braided (new)pump to carb fuel line has been in use on it until this fuel problem started.
Regards
Dawpooldad.
thanks for the replies.
I've not dismantled the pump to check, as it is a new pump effectively on loan from the local club.
When it cools down though, it pumps just as it should, but then starts to get hot again and eventually stops. I guess that I will only find out if I remove the cover to check.
Regarding suppression, I thought that SU used a capacitorfor this. A thought just occurred, if it's electrolytic or tantalum then that could be the problem in the absence of polarity instructions from Burlem.
As to the the inline filter, it is there for me to check the fuel flow wrt the fuel starvation problem. Is there an issue with these units?
I've used them before on this car without any probs although a proper braided (new)pump to carb fuel line has been in use on it until this fuel problem started.
Regards
Dawpooldad.