Fuel pump running VERY hot

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PietereQ
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Fuel pump running VERY hot

Post by PietereQ » Tue Jul 08, 2014 12:15 pm

After around an hour of pretty much spirited driving (no track laps this season yet) i noticed that my auxilary low pressure fuel pump (left) is very hot - like in if you touch it you get burned almost. The efi pump is hot/very warm but you can easily touch it - I know this empirical description isn't very scientific but I don't have IR thermometer. So what to to or not about this, boiling fuel doesn't seem like a good thing on the track...
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kevin
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Re: Fuel pump running VERY hot

Post by kevin » Wed Jul 09, 2014 2:56 pm

Maybe the pumps running dry a few times when fuel is low on right hand bends as its gravity fed . You won't notice as your main pump feeds of your swirl pot which will always have fuel . Check the temp of the pump when your tank half full when you're doing normal driving . Maybe you might have dirt in pump as filter is after pump and is normally before it on the GTV ( I think )
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Re: Fuel pump running VERY hot

Post by Jim K » Wed Jul 09, 2014 6:31 pm

For what its worth, the filter is always placed after the main pump. Your first pump has lots of volume but no pressure, so does not like any restriction.
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Re: Fuel pump running VERY hot

Post by PietereQ » Fri Jul 11, 2014 4:02 am

Thanks for the reply guys! I also was advised by some other people to reconsider filter "position" ie. move it as Jim suggested. Will let you know how it works out.
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MD
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Re: Fuel pump running VERY hot

Post by MD » Fri Jul 11, 2014 9:30 pm

Replace the filter with a new one while you are at it just in case there is a blockage in the existing one from a couple of Polish gherkins..
Last edited by MD on Sat Jul 12, 2014 1:20 am, edited 1 time in total.
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75evo
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Re: Fuel pump running VERY hot

Post by 75evo » Sat Jul 12, 2014 12:08 am

Good point there JK, will keep that in mind.

BTW MD, in Greeceland they tend to drop stolen olives into gas tanks as a pass time.
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MD
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Re: Fuel pump running VERY hot

Post by MD » Sat Jul 12, 2014 1:34 am

Hahaa. That's taking eco friendly a tad too far.

Just thinking out loud here. Often lift pumps are fully immersed inside the fuel tank and no doubt would dissipate some heat onto the fuel thereby keeping it cool. However this pump is being gravity fed and is not submerged and so the operating conditions are not equal. Still, it should be able to cope without generating the sort of temps Peter is concerned about.

The other alternative is to simply use two pressure pumps as the injection pump is not getting overly hot and yet doing harder work. So substituting the suction pump for a second pressure pump would solve that. Before everybody jumps on my neck about this suggestion, keep in mind that the pressure pump will work under these circumstances as it will be gravity fed with a continuous primer. It works well. I use one myself.

Go the gherkin, stuff Olive I say. :mrgreen:
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Re: Fuel pump running VERY hot

Post by PietereQ » Thu Jul 24, 2014 6:50 am

Ok, reporting in.

Unfortunately the new layout hasn't changed the situation a bit. The pump is running freaking hot. At this point I see two options: buy new low pressure pump, or replace the low pressure pump with second efi pump which I'm more biased towards, since I see abundance of setups using dual efi pumps...

Mike, haven't you heard 3 gherkins per tank can boost your octane number by 20%? That's how we invented vodka. You should try it yourself. :D
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MD
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Re: Fuel pump running VERY hot

Post by MD » Thu Jul 24, 2014 2:05 pm

Peter,
I feel confident that your revised efi pump will do the job. Just be sure that there is a good earth and sufficient 12VDC to both pumps UNDER LOAD. A pump may run hot if it is struggling to run with insufficient voltage to punch the current through.

You may also need to revise your fuse ratings and provide no less than a 15amp fuse to each pump. Each pump should have a current drain of around 8-10amps.

Avoid using pissy little gauge wires for high current devices for both polarities.

Check again where your B+ supply is sourced from and be sure it is a good and clean junction. If you want to minimise the voltage drop, install the fuses at the pump end of the supply.

Cheers.
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Re: Fuel pump running VERY hot

Post by MD » Sat Aug 16, 2014 2:22 am

So did you fix it?
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Re: Fuel pump running VERY hot

Post by PietereQ » Mon Aug 18, 2014 9:24 am

Hey Mike. I wanted to make a update on my car and mention it there, but I guess for clarity's sake let's keep it here.
Well as it often happens, one looks for causes in all the wrong places... When I had my car on the lift I noticed that the feed hose was bent in a such way that barely any fuel could get through. I fixed the hose and pump is cool again. I'm changing it for efi pump anyway but the package hasn't arrived yet. And I need a proper fuel cell that's for sure.
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