Matt2e0fgx

Matt2e0fgx

Active Member
How do I check the fuel pressure on my 15p td5 ?

I took the temperature sensor out and fitted adapters to 6mm tube and to a guage , starts and runs but no reading on the guage . Tried another guage and the same, when blow air with an airline it moves up past 4 bar no issues .

what am I doing wrong ?
 
IMO the 6mm tube is too thin. Measure mV with multimeter across the fuel pump's fuse in situ while the engine is running, if you get below 10mV the pump works only on LP
 
sierrafery said:
IMO the 6mm tube is too thin. Measure mV with multimeter across the fuel pump's fuse in situ while the engine is running, if you get below 10mV the pump works only on LP
Click to expand...

6mm internal diameter that is , I will check that tomorrow across the fuse when go down where it's being stored .

Oh when I took the guage off on idle with engine running there is fuel flow but can stop it buy pinching the pipe
 
The regulator works on return and the filter is not involved in HP supply so the pump is the first suspect, the engines used to run like you say only on LP, that mV reading should confirm it
 
sierrafery said:
The regulator works on return and the filter is not involved in HP supply so the pump is the first suspect, they used to run like you say only on LP, that mV reading should confirm it
Click to expand...

it's strange as the pump was new in November and a VDO pump . il check the voltage across the fuse
 
Right I have checked the fuse voltage , 12v to the fuse and when it's running and meter on Mv no reading on the meter at all . Tried 2 meters too .

Even with ignition on and on purge cycle the pasture is not registering on the guage . Il upload a YouTube video
 
Did you measure like in the pic with multimeter set on DC mV ? and are you sure you reached the pins ?

mV voltage across fuse.jpg
 
yes I did , used multimeters for donkeys years so not clueless with them . got another meter but needs a new battery but will check tomorrow .



YouTube link and as can see the pressure isn't great .
 
sierrafery said:
That's definitely low pressure, IMO new pump is needed
Click to expand...

As I thought, Found a battery for a meter that is not auto ranging, il give that a try buy I also have a VDO pump out of another td5 that was only used for a few months before had a accident . Il give that a try .

Strange mine is a few months old vdo unit . making me think to go for genuine but there nearly £500 !
 
Matt2e0fgx said:
Strange mine is a few months old vdo unit .
Click to expand...
Then it should be in warranty, it can happen even to a branded part to fail if you are unlucky... evenntually measure the voltage at the pump's plug while it's running to not be some great voltage drop on the circuit hence low power
 
sierrafery said:
Then it should be in warranty, it can happen even to a branded part to fail if you are unlucky... evenntually measure the voltage at the pump's plug while it's running to not be some great voltage drop on the circuit hence low power
Click to expand...

Today I have swapped the pumps over so how I have a few month old VDO in there and after left to do the full prime sequence it fired up with a flick of the key.
Whist running voltage across fuse 10 is 0.32v and at the pump is 14.15V pressure is showing upto 1 bar but when rev the engine the needle flutters and jumps like a mad thing ! Could this indicate a iffy FPR ?

FPR was rebuilt with h a Bosch unit off eBay! I'm wondering may be worth replacing it with a Genuine part , gasket and clean the gauze filter ?
 
Seems that it was the pump, i presume that you have better pressure from that pipe now. It's possible that the FPR to be the problem but IMO that pipe to the gauge is a bit too thin, at least do you feel improvement in power and how the engine is running?
 
sierrafery said:
Seems that it was the pump, i presume that you have better pressure from that pipe now. It's possible that the FPR to be the problem but IMO that pipe to the gauge is a bit too thin, at least do you feel improvement in power and how the engine is running?
Click to expand...
pipe diameter wont effect pressure reading,old fashioned direct piped oil pressure gauges had far thinner bore pipe
 
sierrafery said:
Seems that it was the pump, i presume that you have better pressure from that pipe now. It's possible that the FPR to be the problem but IMO that pipe to the gauge is a bit too thin, at least do you feel improvement in power and how the engine is running?
Click to expand...

still a bit lumpy and slight vibration on idle but is a bit smoother , its sorned so can not drive it on the road but I can try around the yard in low box .

So the Mv reading is fine ?

I may order a fuel pressure test kit or see if anyone i know has one .
 
still missing slightly on idle, but when you rev the engine the fuel pressure goes down , at idle sitting around 0.5 bar.

I'm thinking may be time to try a complete fpr and housing .
 
Matt2e0fgx said:
still missing slightly on idle, but when you rev the engine the fuel pressure goes down , at idle sitting around 0.5 bar.

I'm thinking may be time to try a complete fpr and housing .
Click to expand...
Quite honestly the housing should last the life of the vehicle unless physically damaged by an impact or similar.
I fitted a bosch FPR on mine and it works fine, but when I connected a pressure gauge into the FPR (using the temp sender location) I see 4 bars pressure which is as it should be.
The pump should deliver more than that and the FPR opens up and diverts the excess flow back to the tank, just maintaining 4 bars in the head gallery supplying the injectors, as you load the engine more the FPR will divert less back to tank as the injectors take more and more is needed to maintain the 4 bars in the head.
Just a thought but there are two types of FPR gasket with holes in different places one for 10p engines and one for the 15 p engines did you get the right one?
You need to nail down why you have a low pressure at the delivery, could you take the delivery pipe off again and connect the pressure gauge onto the end so you see the actual pressure being developed by the pump.
 
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