Discussion
Since carrying out a body lift restoration I am having a few problems. Any suggestions much appreciated.
It has been 8 months since starting the job so all fuel lines will have dried out. I found a problem with the original fuel pump, it was intermittent so installed the correct Bosch replacement and it now primes every time when ignition is initially turned on. But the car does not start.
Checking for the fuel supply first I could not detect any fuel pressure when depressing the bleed valve on the injector rail, shoud the initial pump prime be enough to pressurise the rail or does the pump have to run continuously to enable that?
I suspect also that there is no spark either so this would inhibit the pump running but thought to sort the fuel side first. I have checked the fuel line from filter to the pressure regulator and it is clear. Maybe the Pressure regulator has failed although they seem very simple devices.
Any suggestions?
Cheers
Paul
It has been 8 months since starting the job so all fuel lines will have dried out. I found a problem with the original fuel pump, it was intermittent so installed the correct Bosch replacement and it now primes every time when ignition is initially turned on. But the car does not start.
Checking for the fuel supply first I could not detect any fuel pressure when depressing the bleed valve on the injector rail, shoud the initial pump prime be enough to pressurise the rail or does the pump have to run continuously to enable that?
I suspect also that there is no spark either so this would inhibit the pump running but thought to sort the fuel side first. I have checked the fuel line from filter to the pressure regulator and it is clear. Maybe the Pressure regulator has failed although they seem very simple devices.
Any suggestions?
Cheers
Paul
Edited by Loubaruch on Monday 2nd September 10:14
Sounds silly but try the fuel pump wires round the other way. Won’t do any harm.
Priming should pressurise the rail.
Also check you have connected the lines up the right way at the rail.
I recently fitted a new pump and the +\- were the wrong way round on the pump.
After checking the above and getting no pressure and trying everything eventually tried reversing the wires and bingo.
Priming should pressurise the rail.
Also check you have connected the lines up the right way at the rail.
I recently fitted a new pump and the +\- were the wrong way round on the pump.
After checking the above and getting no pressure and trying everything eventually tried reversing the wires and bingo.
Loubaruch said:
Thanks Alun, But the pump connections are OK, I am beginning to suspect the pressure regulator.
Have you disconnected the fuel pipe off the pump and tried priming it.
Tip, have a container and rag handy
If no fuel appears try reversing the wires. If still no fuel your pumps s
te. Why would the regulator suddenly fail if it was working perfectly well before you drained the system.
Mine was drained for well over a year before I connected it all up and works fine.
Edited by BritishTvr450 on Monday 2nd September 10:23
I disconnected the fuel pipe at the regulator input and plenty of pressure in the line about 1/4 pint caught in a container after the initial burst., I have ordered a new pressure regulator to rule that out. No fuel came out of the regulator when taking it off the engine,that surprised me.
Thanks but as I have plenty of pressure going into the regulator The pump must be pushing not pulling.
My next move is to run the pump continuously by an external cable and see if fuel can then get through the regulator. The regulator is out of the engine in a container so I can observe the result.
My next move is to run the pump continuously by an external cable and see if fuel can then get through the regulator. The regulator is out of the engine in a container so I can observe the result.
With the pressure regulator in a large plastic bottle with the top cut off I connected the fuel pump to an external supply and it ran for 15-20 seconds then stopped presumably as the back pressure had switched it off. Not a drop of fuel through the regulator. I suppose the new pump could be faulty also but the pressure when I released the fuel pipe suggests otherwise, new regulator on its way.
I understand your thinking and if you have connected the pump to an external line I can’t understand why you don’t just try priming it and putting the pipe into a catch tank.
You’ll see straight away if fuel emerges, if so then your right to be checking regulator.
After my body off and new pipe work the fuel rail was dry as a bone.
Pulled a plug to check if I had a spark, turned ignition on, pump primed for about 3 seconds and within 2-3 seconds of cranking it fired up which suggests the fuel will be reaching the plugs very quickly indeed.
You’ll see straight away if fuel emerges, if so then your right to be checking regulator.
After my body off and new pipe work the fuel rail was dry as a bone.
Pulled a plug to check if I had a spark, turned ignition on, pump primed for about 3 seconds and within 2-3 seconds of cranking it fired up which suggests the fuel will be reaching the plugs very quickly indeed.
Loubaruch said:
Alun I proved that the pump is delivering fuel when priming a few posts back, I wanted to see if the pump running continuously would force fuel through the regulator. Not looking forward to taking the pipe off the regulator as the pump ran until back pressure cut it off!
Ah sorry mate I missed that. Cool
Loubaruch said:
Alun I proved that the pump is delivering fuel when priming a few posts back, I wanted to see if the pump running continuously would force fuel through the regulator. Not looking forward to taking the pipe off the regulator as the pump ran until back pressure cut it off!
Fuel pump dont run until back pressure turns it off 
it will just run continuously if you have jumpered/hot-wired it rather than commanded by ECU timing out the FP relay thus switching pump off due to no ign activity Alun you were right the new Pressure regulator still does not pass fuel. The Penny finally dropped ( advanced senile dementia so took a while)
There had to be some restriction in the flow as the pump was brand new although it seemed to gush out.
I had a close look underneath and noticed that the body had crushed the main fuel pipe, hopefully not permanent.
Thanks for all the comments.
There had to be some restriction in the flow as the pump was brand new although it seemed to gush out.
I had a close look underneath and noticed that the body had crushed the main fuel pipe, hopefully not permanent.
Thanks for all the comments.
IME fuel press reg's fail either leaking fuel into small vacuum line nipple and into intake manifold (rich/overfueling etc) or open prem i.e low fuel pressure (excess fuel back into return line) and not any other way ive ever seen , but if you have a restricting FP inlet thats not good
I stand corrected but I thought that the Bosch fuel pump has a pressure switch that shuts off the input when back pressure exceeds a certain amount so even if the ECU sends 12 v to drive it no more fuel will exit until the back pressure drops.
I connected the pressure regulator straight to the fuel pump and switched on the ignition to give it a few primes, some fuel did then come out of the regulator but very little only a thimble full not nearly enough to pressurise the injector rail so perhaps the pump has to run continuously ( i.e. ) normally for the rail to be correctly pressurised and the prime just gives it a blip to top the pressure up. Another problem during testing, the immobiliser failed to respond but traced to corroded fuses behind the dash. Maybe caused as the car has been laid up for 8 months and not used.
I connected the pressure regulator straight to the fuel pump and switched on the ignition to give it a few primes, some fuel did then come out of the regulator but very little only a thimble full not nearly enough to pressurise the injector rail so perhaps the pump has to run continuously ( i.e. ) normally for the rail to be correctly pressurised and the prime just gives it a blip to top the pressure up. Another problem during testing, the immobiliser failed to respond but traced to corroded fuses behind the dash. Maybe caused as the car has been laid up for 8 months and not used.
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