P38 no fuel to filter but runs???

dubbleRR · Jul 10, 2022

Think it is possible to mix up the pipes on the tank ,and if they are the wrong way round ,then you will get fuel pumping from the return pipe

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Chrispndry · Jul 10, 2022

Chrispndry said:
Gonna try new pipe from itp to filter

Its starts but runs erratically it's only getting fuel that the injection pump is pulling the itp and the auxiliary pump that was fitted gets power then stops...the garage bridged the pump relay we could hear it run he disconnected the pipe to the filter but nothing came through even when cranking...reconnected it cranked fired up but loads of air...continues to have air in clear pipe...always fires up rund 3..4..miles 30..40 mph then struggle..

Flossie · Jul 10, 2022

Have you fitted a heat exchanger.?

Chrispndry · Jul 10, 2022

No not fitted exchanger...changed main filter first as I thought it was blocking up...the fitted new itp...the tried auxiliary pump...relay kick pump inn but then they stop....running 50/50....was on 100% for 4 weeks till it started losing power hence filter change

Datatek · Jul 10, 2022

Chrispndry said:
No not fitted exchanger...changed main filter first as I thought it was blocking up...the fitted new itp...the tried auxiliary pump...relay kick pump inn but then they stop....running 50/50....was on 100% for 4 weeks till it started losing power hence filter change

100% veg oil can lead to glycerine separating out and blocking things

Datatek · Jul 10, 2022

Flossie said:
I wonder if you can blow compressed air down the flow pipe to hopefully clear a potential blockage? Don't know if that will damage the in tank pump though?

Worth a try, it will not damage the pump but if it's the version fitted with a non return valve it could damage that if too much pressure is applied.

Mark Piercy · Jul 10, 2022

I'd check the intank pump is connected properly.. Then flush the tank and just try some diesel before going back onto veg oil.

Chrispndry · Jul 10, 2022

But new pump...new auxiliary pump...new fuel line new filter...no fuel....got to be a cut off switch somewhere gonna try with direct fused live to pump tomorrow....maybe try to pull fuel.to injection pump get rid of air...it ran great until filter change.

Mark Piercy · Jul 11, 2022

Chrispndry said:
But new pump...new auxiliary pump...new fuel line new filter...no fuel....got to be a cut off switch somewhere gonna try with direct fused live to pump tomorrow....maybe try to pull fuel.to injection pump get rid of air...it ran great until filter change.

Unless the filter seal is deformed?

Datatek · Jul 11, 2022

Chrispndry said:
But new pump...new auxiliary pump...new fuel line new filter...no fuel....got to be a cut off switch somewhere gonna try with direct fused live to pump tomorrow....maybe try to pull fuel.to injection pump get rid of air...it ran great until filter change.

Why the auxiliary pump? If you can hear the pump run, what is the point of running a separate feed?

Grrrrrr · Jul 11, 2022

Chrispndry said:
Yes Running veg oil

Might be bacterial growth blocking the fuel pipe. Loss of sync to EMS would stop pump too.

Datatek · Jul 11, 2022

Grrrrrr said:
Might be bacterial growth blocking the fuel pipe. Loss of sync to EMS would stop pump too.

But he say's the pump runs

Flossie · Jul 11, 2022

Drop the tank. Either the itp is knacked or blocked with a burnt chip.
One final thought, this auxiliary pump, they are directional, usually an arrow on in and out marked on it. Got that the right way round?

Datatek · Jul 11, 2022

There is conflicting information. The engine runs, so the FIP can suck fuel through.
The pump runs but produces no fuel at the filter.
To my mind that indicates a duff pump or as Flossie say's the auxiliary pump is causing a problem.
I'd get rid of the auxiliary pump, it's not needed and is one less thing to worry about. If still no fuel, time to drop the tank and check the lift pipe from the pump is n not broken.

Grrrrrr · Jul 12, 2022

Datatek said:
But he say's the pump runs

I'm unsure if loss of sync stops the lift pump? It still cranks and the glows still work after all.

Datatek · Jul 12, 2022

Grrrrrr said:
I'm unsure if loss of sync stops the lift pump? It still cranks and the glows still work after all.

It also runs, just not well.

Chrispndry · Jul 13, 2022

Update...took itp off now has inline pump only linked to wiring from relay etc. Pick up pipe to about 1 inch from.tank bottom..fuel now to filter but still loads of air runs gets up to 50mph dies struggles then increases now running 80% diesel 20% veg...

Datatek · Jul 13, 2022

Chrispndry said:
Update...took itp off now has inline pump only linked to wiring from relay etc. Pick up pipe to about 1 inch from.tank bottom..fuel now to filter but still loads of air runs gets up to 50mph dies struggles then increases now running 80% diesel 20% veg...

Just a bare pipe end with no pick up chamber? How full is the tank??

Flossie · Jul 13, 2022

Could be an air leak in the lash up you've installed.

Flossie · Jul 13, 2022

The pick up pipe all the way to the filter needs to be air tight. It could be an incorrect fuel filter, mine had 2 sealing rings on the filter when I got it but needs only 1 on the filter, the other is in the filter head.

P38 no fuel to filter but runs???

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