Signs of a failing Fuel Pressure Regulator?

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M3THANOL
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Signs of a failing Fuel Pressure Regulator?

Post by M3THANOL »

Morning all

I am beginning to think that the FPR (Fuel Pressure Regulator) on my 2.0 8v AGG is not working as it should. The symptoms include:

1) On cold start in the mornings the engine cranks, starts and then dies after about two seconds, then usually starts and runs on the second try, but sometimes it dies again and then runs fine on the 3rd try

2) Once the engine is hot, if I switch it off and then come back say half an hour to an hour later ( if I go to the shops, or park at home and then need to go out again) the engine will start and idle for a few seconds and if I don't blip the throttle a few times it will die but once I have given it a few blips it idles fine, with the occasional "drop" or hunt in the revs for a short while until I start driving.

3) I have noticed that when I turn the ignition on and allow the pump to prime for a while without starting, I can hear an unusual bubbling type sound coming from the fuel rail, not something that can be heard when the engine is running but only when the pump is priming.

I haven't yet tested to see if petrol comes out of the vacuum port on the FPR, I will give it a try today but I thought it would be best to get a thread going where some possibilities can be listed.

Thanks
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Re: Signs of a failing Fuel Pressure Regulator?

Post by THANAS »

M3THANOL wrote:Morning all

I am beginning to think that the FPR (Fuel Pressure Regulator) on my 2.0 8v AGG is not working as it should. The symptoms include:

1) On cold start in the mornings the engine cranks, starts and then dies after about two seconds, then usually starts and runs on the second try, but sometimes it dies again and then runs fine on the 3rd try

2) Once the engine is hot, if I switch it off and then come back say half an hour to an hour later ( if I go to the shops, or park at home and then need to go out again) the engine will start and idle for a few seconds and if I don't blip the throttle a few times it will die but once I have given it a few blips it idles fine, with the occasional "drop" or hunt in the revs for a short while until I start driving.

3) I have noticed that when I turn the ignition on and allow the pump to prime for a while without starting, I can hear an unusual bubbling type sound coming from the fuel rail, not something that can be heard when the engine is running but only when the pump is priming.

As far as I know that's the sound of the fuel returning to the tank and indicates that the FPR is achieving its 'requested' pressure and allowing fuel past. If it's failing however it will allow fuel past after reaching a pressure lower than 3Bar, which is what causes the problem. It however is not a sign of a failing FPR.

I haven't yet tested to see if petrol comes out of the vacuum port on the FPR, I will give it a try today but I thought it would be best to get a thread going where some possibilities can be listed.

I don't believe that fuel will ever come out of the vacuum port/tube. If i'm not mistaken that is just to allow the FPR to adjust according to the difference between manifold and atmospheric pressure.

Thanks
Not 100% convinced it's the FPR, you should be noticing a drop in power/running lean if it starts failing. Your water temp sensor may be on it's way out or in need of calibration.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by nd_s »

Put a fuel pressure guage on it and see what its doing.

I had a feeling mine was giving crap from the loads of fuel the car was using.
When fuel pressure is low, would also not rev up cleanly and sometimes jerk high up in rev range.

Starting then dying sounds like cold start or temp sensor on its way out.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by M3THANOL »

CCBB wrote:
M3THANOL wrote:Morning all

I am beginning to think that the FPR (Fuel Pressure Regulator) on my 2.0 8v AGG is not working as it should. The symptoms include:

1) On cold start in the mornings the engine cranks, starts and then dies after about two seconds, then usually starts and runs on the second try, but sometimes it dies again and then runs fine on the 3rd try

2) Once the engine is hot, if I switch it off and then come back say half an hour to an hour later ( if I go to the shops, or park at home and then need to go out again) the engine will start and idle for a few seconds and if I don't blip the throttle a few times it will die but once I have given it a few blips it idles fine, with the occasional "drop" or hunt in the revs for a short while until I start driving.

3) I have noticed that when I turn the ignition on and allow the pump to prime for a while without starting, I can hear an unusual bubbling type sound coming from the fuel rail, not something that can be heard when the engine is running but only when the pump is priming.

As far as I know that's the sound of the fuel returning to the tank and indicates that the FPR is achieving its 'requested' pressure and allowing fuel past. If it's failing however it will allow fuel past after reaching a pressure lower than 3Bar, which is what causes the problem. It however is not a sign of a failing FPR.

I haven't yet tested to see if petrol comes out of the vacuum port on the FPR, I will give it a try today but I thought it would be best to get a thread going where some possibilities can be listed.

I don't believe that fuel will ever come out of the vacuum port/tube. If i'm not mistaken that is just to allow the FPR to adjust according to the difference between manifold and atmospheric pressure.

Thanks
Not 100% convinced it's the FPR, you should be noticing a drop in power/running lean if it starts failing. Your water temp sensor may be on it's way out or in need of calibration.
thanks for the input bud, will keep it in kind. One will find fuel coming through the vacuum port if the diaphragm has a tear in it.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by M3THANOL »

nd_s wrote:Put a fuel pressure guage on it and see what its doing.

I had a feeling mine was giving crap from the loads of fuel the car was using.
When fuel pressure is low, would also not rev up cleanly and sometimes jerk high up in rev range.

Starting then dying sounds like cold start or temp sensor on its way out.
I don't have a fuel pressure gauge yet, I guess I should look into getting one.

I will hook up my laptop today to the XMS and see if anything is out of the ordinary.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by RIAZ »

Good day

My VW CitiRox starts and dies after two seconds sometimes very rarely but it irritates the hell out of me , even after i changed the temp sensor put one in from vw it still does it but very very rarely any help

Thank you
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Re: Signs of a failing Fuel Pressure Regulator?

Post by Viper »

Fuel rail are more common to go. They crack on the inside and then start bypassing the regular. Try to clamp the return ans if there is a noticeable difference.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by RIAZ »

how would one repair this if it is the fuel rail , cost of spares ? labour
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Re: Signs of a failing Fuel Pressure Regulator?

Post by Viper »

Replace fuel rail. About R1000.00
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Re: Signs of a failing Fuel Pressure Regulator?

Post by nd_s »

Riaz Amod wrote:how would one repair this if it is the fuel rail , cost of spares ? labour
Put a external regulator on..
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Re: Signs of a failing Fuel Pressure Regulator?

Post by M3THANOL »

Viper wrote:Fuel rail are more common to go. They crack on the inside and then start bypassing the regular. Try to clamp the return ans if there is a noticeable difference.
shot Viper :hug: , will give it a try
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Re: Signs of a failing Fuel Pressure Regulator?

Post by jacobs12 »

Hey i have a golf gti mrk 7 and have the exact same issue, ive had the same issue for the last 8 months and please could you tell me how you resolved it. I have changed many things such as the breather, camb belt sensor and nothing has resolved it.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by panic-mechanic »

Golf 7 has a vastly different setup to the car above. Not anything in this thread will even remotely assist you in solving a fuel issue on a golf7.
Start a new thread of your own describing your issues.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by BIGMIG »

Can also try the search function. Might be a bit tricky but could help you out.
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Re: Signs of a failing Fuel Pressure Regulator?

Post by joaquimMoose »

hi all i also have an golf cabrio with agg motor where does one plug in the pressure tester, as i cnt see a place on the fuel rail

thanks in advance
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