Fuel Injection woes. |
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INSTG8R
Falcone Joined: 31 May 2017 Location: Geraldton Status: Offline Points: 31 |
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Cheers Brian,
I think you're onto something. This weekend will be fuel pressure test time me thinks.
I did have to make my own fuel lines up, following the Guzzi fuel flow diagram as the Suzuki outlet and return spouts were different to the Guzzi tank. I also had to re-position the Guzzi fuel filter as things were hitting the tank and frame. Even Mario was scratching his head as to why it was rich instead of lean. It will be the one thing we didn't think of or test. I often remind myself of the true meaning of the word "assume", ass-u-me. hahahaha. |
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INSTG8R
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INSTG8R
Falcone Joined: 31 May 2017 Location: Geraldton Status: Offline Points: 31 |
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Ok, prognosis: too much fuel Pressure. It appears the pressure relief valve is not doing its job. Fuel pressure to the injectors is meant to be 3 bar +/- .02(42-47psi). I have over 5 bar 110-115psi. Are the pressure valves repairable or replacement only? As I believe the original part have not been available for many years.
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INSTG8R
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Can't give you a straight answer to that. But I do know that adjustable regulators are available. Are you sure the pressure leak off pipe is clear back into the tank? You said you had to alter all the pipework as the tank you now have is different. So many times we have seen that a recent modification is in fact the cause of a problem which occurs just after.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Gianni
Senior Member Joined: 16 May 2014 Location: Muswell Hill Status: Offline Points: 676 |
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Check the pressure return pipe into the tank - it was kinked on my Quota and might have been responsible for some issues I had (other components were also suspect so not definitive).
Adjustable solution available from S-D at a price https://www.stein-dinse.biz/product_info.php?products_id=439056#prettyPhoto
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Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Think about it, if that pipe is kinked and so flow drastically restricted then excess fuel cannot return to the tank, so you will get too much pressure at the injectors.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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INSTG8R
Falcone Joined: 31 May 2017 Location: Geraldton Status: Offline Points: 31 |
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Thanks lads but I had the tank off, no pipe kinks and all fuel lines are new with no blockages. I checked pressure between pump and filter, filter and relief valve, relief valve and injectors as well as relief valve and tank return. The tank return side didn’t register any pressure but fuel was flowing slowly. The pressure before the relief valve was 140psi after the valve the 110-115psi. All fingers point to the relief valve. At the meeting moment.
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INSTG8R
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guzzwiz
Senior Member Joined: 05 Oct 2019 Location: Germany Status: Offline Points: 155 |
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Question: Why Moto Guzzi has spent 2 independant air temp sensors, and placed them at different positions? Because they had overstock? Answer: No, because they are necessary in such arrangement. Imho, it is also nonsens to mount them side-by-side. I don't expect issues with the fuel pressure. I recommend to discard the pod filders, and put back the old filter box, together with the ATS in its original position. Next tip: get the free "GuzziDiag diagnostic PC programme, the appropriate OBDII-USB adapter and the Alfa/FIAT-AMP Superseal cable. This is the necessary toolset to work on a Guzzi with EFI. Forget your knowledge about carburettors on such bikes. Important: the "air screws" are for idle rpm control and vacuum pressure synchronization only, don't try to ennrich or lean gas mixture with them. Cheers Hans |
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presently a modified 1000G5 and a V7classic; (V50PA sold)
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Agreed, it does seem the regulator isn't doing it's job properly. 110psi is around 7 Bar, which would give a very rich mixture.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Gianni
Senior Member Joined: 16 May 2014 Location: Muswell Hill Status: Offline Points: 676 |
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I had a conversation with a Guzzi racing engineer recently during which he said they used to modify the standard part in order to raise the point at which the pressure was relieved in order to increase fuel delivery. The modification involved opening the valve.
So it might be possible to open it up and see what is causing the issue. In my case the internal rubber diaphragm failed so the pressure was relieved out of the drain spigot into the hot exhaust pipes
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Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Increasing fuel pressure is a known tuning aid, but it has to be done with great control.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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INSTG8R
Falcone Joined: 31 May 2017 Location: Geraldton Status: Offline Points: 31 |
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SUCCESS!!!! As I have changes the tank, repositioned the fuel filter on the frame, the fuel flow from the tank -> pump -> filter -> pressure relief valve -> back to tank must have confused the poor old mechanic working for Mario. on a previous visit he said I had the pressure relief valve back to front so he turned it around for me. (thanks) However after connecting a pressure gauge it worked out I had it correct in the first place. Switched it round, Runs like a dream!! Went for a lovely ride through the local farming district, green wheat fields, yellow canola fields and glorious sunshine. I'm back in love with my old tractor . Thanks to all for you input and suggestions. Once agin a cracking community!
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INSTG8R
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Well at least you know the pump is giving good pressure.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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