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External EFI fuel pump getting hot
Alan B - 28/5/11 at 07:17 PM

Hi guys,

Just fitted an external Walbro GLS 392 external fuel pump feeding my Honda VTEC in my middy build.

No leaks, starts well, runs great, but the pump body gets too hot to touch within about two minutes running.

Questions..

1 - Is this normal? can't imagine it is...
2 - If not what could the problem be?

Cheers,

Alan

theconrodkid - 28/5/11 at 08:44 PM

had this on mine,the inlet was 13mm? but i had put a reducer to make it fit the tank outlet of 8mm?.
the pump always sounded like it was struggling.
pump eventually died,put a bigger tank outlet on and problem solved

all dims are approximate.

BaileyPerformance - 28/5/11 at 09:02 PM

quote:
Originally posted by Alan B
Hi guys,

Just fitted an external Walbro GLS 392 external fuel pump feeding my Honda VTEC in my middy build.

No leaks, starts well, runs great, but the pump body gets too hot to touch within about two minutes running.

Questions..

1 - Is this normal? can't imagine it is...
2 - If not what could the problem be?

Cheers,

Alan


As the conrodkid said chk the inlet, the pump should be mounted so it has a head of fuel - it should not be forced to suck fuel, this can cause cavitation.
Also chk fuel pressure, if excessive the pump will lockout (valve inside the pump opens, diverting fuel back into the pump body/inlet) as the fuel flow cools the pump (in normal conditions) if in lockout the same fuel goes around and around causing the pump to over heat.

High fuel pressure can be caused by a faulty fuel reg, incorrect piping (outlet of reg connected to pump when it should be connected to fuel rail) or a restricted return to the tank

Alan B - 28/5/11 at 09:46 PM

Thanks for the help so far.

I wonder if there is fundamental piping snafu?

Originally it had a civic in-tank pump (one pipe out, no return as could see...is this likely?)

I then changed it to gravity feed to an external pump and then pipe up to the fuel rail...there does not appear to be any return piping or provision for any. Is it possible that there is a fuel return connection that has been blocked off all along?

If anyone has a piping schematic for the 05 civic si that would probably help too.

Cheers,

Alan

BaileyPerformance - 28/5/11 at 10:03 PM

quote:
Originally posted by Alan B
Thanks for the help so far.

I wonder if there is fundamental piping snafu?

Originally it had a civic in-tank pump (one pipe out, no return as could see...is this likely?)

I then changed it to gravity feed to an external pump and then pipe up to the fuel rail...there does not appear to be any return piping or provision for any. Is it possible that there is a fuel return connection that has been blocked off all along?

If anyone has a piping schematic for the 05 civic si that would probably help too.

Cheers,

Alan

Hi,

Some jap cars and bikes only have one fuel pipe to the engine, sometimes the regulator is built into the internal pump housing within the fuel tank. Have a look at the old pump if you still have it, if there is regulator then no problem, you can T into the fuel line and fit an external regulator with a return to the tank.

Don't use the car until you have sorted, overheating the pump (in lockout) will cause the pump to get VERY hot, this may cause a fire!

Chippy - 28/5/11 at 10:07 PM

Did this for another member, may be of help to you. HTH Ray
[img] Fuel set up
Fuel set up [/img]

Alan B - 28/5/11 at 11:04 PM

quote:


Hi,

Some jap cars and bikes only have one fuel pipe to the engine, sometimes the regulator is built into the internal pump housing within the fuel tank. Have a look at the old pump if you still have it, if there is regulator then no problem, you can T into the fuel line and fit an external regulator with a return to the tank.

Don't use the car until you have sorted, overheating the pump (in lockout) will cause the pump to get VERY hot, this may cause a fire!


I bet that is what it is....I do seem to recall something like a regulator within the in-tank setup.
So I better get a regulator to tee in and return to the tank..

Cheers,

Alan


Ray,

Cheers for the diagram

Alan

spiderman - 28/5/11 at 11:47 PM

If it is not a fuel return problem it may be an electrical problem, check that you have a good earth connection also if the earthing wire (if you have one, possibly earthed through body mountings) gets hot then it is a bad earth, especially as it gets hot so quickly.

Alan B - 5/6/11 at 09:47 PM

quote:
Originally posted by BaileyPerformance
Hi,

Some jap cars and bikes only have one fuel pipe to the engine, sometimes the regulator is built into the internal pump housing within the fuel tank. Have a look at the old pump if you still have it, if there is regulator then no problem, you can T into the fuel line and fit an external regulator with a return to the tank.

Don't use the car until you have sorted, overheating the pump (in lockout) will cause the pump to get VERY hot, this may cause a fire!


BINGO, this was exactly the problem.
I fitted a pressure regulator tee'd off the main line to the fuel rail and that's solved it.

Not only is the pump not getting hot or even warm it's actually colder than it's surroundingd (floor, chassis tube) showing that the fuel flow is doing it's cooling job.

Thanks very much to BP for the spot on advice and everyone else who chipped in too.

Cheers,

Alan

(Now onto the next issue........)