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Author: Subject: Fuel pump won't pump Fuel
pekwah1

posted on 22/3/17 at 09:45 AM Reply With Quote
Fuel pump won't pump Fuel

Hi Guys,

I think i've created a palindrome of words there!!

I'm having some trouble with my fuel pump.
Its a bosch inline type style, but just can't get it pumping and i think it's supply to the pump rather than anything else.

With the pump connnected, i just can't get it pumping fuel down the fuel line, or even with the end pipe off doesn't want to know.
I can siphon fuel from the tank with the pump disconnected, so would appear to be running free enough, but the pump won't pull the fuel through.

So just after some advice here, i've heard that you have "push" or "pull" type pumps, so not sure if mine's just not up to it?

Some photos to give an idea of the setup:





Oh and ignore the stain that looks like the tank is leaking - it isn't....

Cheers,
Andy

[Edited on 22/3/17 by pekwah1]

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Dick

posted on 22/3/17 at 09:56 AM Reply With Quote
Change the wires over would be my first thing to try
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pekwah1

posted on 22/3/17 at 10:25 AM Reply With Quote
by wires, do you mean pos + and neg - ?

I haven't done this, but did switch the hoses round in case i was being a moron, didn't make any difference.

I had an M5 and M4 connection on the pump, i've put neg to M4 and pos to M5

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Nickp

posted on 22/3/17 at 10:26 AM Reply With Quote
quote:
Originally posted by Dick
Change the wires over would be my first thing to try


If that doesn't work then gravity feed some fuel into it, that'll give you your answer.
BTW is your tank baffled or have a sump? If not then you'll be asking for trouble as your fuel level drops, with fuel surge / starvation. I've got a low pressure pump feeding a swirl pot which in turn gravity feeds my high pressure pump.

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pekwah1

posted on 22/3/17 at 10:29 AM Reply With Quote
Yes i had this setup originally, but not at the moment, maybe i will change it again....
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Nickp

posted on 22/3/17 at 10:39 AM Reply With Quote
quote:
Originally posted by pekwah1
Yes i had this setup originally, but not at the moment, maybe i will change it again....


You really don't want to lose fuel supply to your HP pump at all.

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gremlin1234

posted on 22/3/17 at 11:06 AM Reply With Quote
that style of pump doesn't suck, it requires flood fill
often the easiest way to do this is with a LP pump, unless putting the HP pump inside the tank is possible.

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pekwah1

posted on 22/3/17 at 11:13 AM Reply With Quote
Thanks guys,

so a LP pump would generally suck (i.e. the facet type?)

That's actually the setup i had on my previous car with a swirl pot, just haven't got round to buying the LP and swirl yet...

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ElmrPhD

posted on 22/3/17 at 12:48 PM Reply With Quote
Your wires are reversed.
Should be M5 to ground, M4 to 12V (Well, hopefully a bit more than 12V, but you know...)
The "+" and "-" are actually labelled on that brown plastic/resin output end. They're just REALLY hard to see.
Hopefully the pump hasn't been damaged by running dry.
Good luck!

Steve, in the NLs

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garyo

posted on 22/3/17 at 12:48 PM Reply With Quote
Or gravity feed it from a new tail fitted to the bottom of the tank. That worked on my last car: pump mounted 1cm lower than the tank, and I also fitted in in-line swirl pot horizontally to take the return from the engine bay so that the fact that tank didn't have baffles didn't matter.
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benchmark51

posted on 22/3/17 at 08:45 PM Reply With Quote
I have a facet pump and was told it needs to be mounted near the tank outlet and low. It doesn't like to suck uphill much but will push the fuel to the front end ok. That's what I did and it works a treat, keeps the twin 40's fed and without a pressure regulator. I intended to fit a reg, but found it didn't need it.
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pekwah1

posted on 22/3/17 at 08:51 PM Reply With Quote
You'll all be glad to hear that since this post I have now bought a facet pump and swirl pot, so will get it hooked up once it's arrived and all should be good in the world!
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ElmrPhD

posted on 23/3/17 at 12:46 PM Reply With Quote
Have you switched the wires around, yet?
Do that first or you'll continue to toast your pump.
Again, M5 for GROUND/EARTH, M4 for power feed.
Prime the pump somehow, then turn it on and see if you still need a feed/lift pump.

Steve, in the NLs

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pekwah1

posted on 23/3/17 at 04:43 PM Reply With Quote
No haven't swapped the wires yet, decided to just get a facet and swirl pot anyway so will get them installed first and see how I go!
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ElmrPhD

posted on 24/3/17 at 06:59 AM Reply With Quote
Well, I double-checked my own pump, yesterday (exactly like yours) and confirmed that the larger terminal is for negative/earth/ground.
The + and - signs are there, but very difficult to see.
Funny, a Google search showed the symbols like I just described, but the text description wrongly said to connect them like you originally did. Indeed, it's a bit counterintuitive, but it reiterates that the ground side of the circuit is AT LEAST as important as the power feed side...

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pekwah1

posted on 24/3/17 at 09:39 AM Reply With Quote
Thanks, i took mine off and there are NO symbols at all.... just made the assumption a bigger terminal must be live, but you know what they say about assumptions! Anyway, Low pressure and swirl on their way so i guess i'll stop cutting corners and just do it properly now!

Cheers,
Andy

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