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Fuel Injection woes.

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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Topic: Fuel Injection woes.
    Posted: 19 Jul 2021 at 08:12
Well at least you know the pump is giving good pressure.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote INSTG8R Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jul 2021 at 04:04
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 Big smile. Thanks to all for you input and suggestions. Once agin a cracking community!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 17:15
Increasing fuel pressure is a known tuning aid, but it has to be done with great control.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gianni Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 16:40
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 Ouch
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 14:38
Originally posted by INSTG8R INSTG8R wrote:

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.

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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Post Options Post Options   Thanks (0) Thanks(0)   Quote guzzwiz Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 13:42
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote INSTG8R Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 11:26
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 11:15
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gianni Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2021 at 00:21
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2021 at 16:00
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote INSTG8R Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2021 at 14:45
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote INSTG8R Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 2021 at 12:20
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 2021 at 08:28
If you have had Mario on the case, then I would suggest you follow his advice. Few in Aus know more than him.

8 stroking is when the engine is getting too much fuel and so only fires every second firing stroke. It happens on carbed engines too. It's not the ECU telling the injectors to do anything.

If the pressure relief valve isn't working correctly you could be getting much higher pressure in the fuel line, which in turn will mean far more fuel injected. If you have moved it and done anything to it, that would be my first thing to investigate.
Have you checked the fuel relief line back to the tank and made sure that's clear, if that's blocked the exess fuel pressure will build up anyway. It is a mechanical pressure relief valve I believe.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote INSTG8R Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 2021 at 04:05
Thanks Guys for all your input! Thought I would right 1 reply to all rather than individual.
Firstly to Guzzished and Brian) Man if you saw the state this bike was in when I acquired it, dropped several times, hand painted by brush and fire damage to the left hand side. She was not pretty and never going to be a restoration project, but I digress. I mounted the Intake Air Temp Sensor to the same bracket as the the Ambient Air temp sensor, so they are side by side. Mario the Magician from Thunderbikes Western Australia tested all sensor values (Air, engine temp, tps, timing signals and voltage regulator) both engine cold and varying temps and they are all with in factory spec. 
Tank was cleaned and fresh fuel with injector cleaner added as the old original tank did have stale fuel when I removed it although it ran well.
Andrew- Guzzished has assumed correctly the TPS and Injectors are original. I did remove the injectors to test open and close operation but not spray patter or leakage, Thanks Brian for this tip. Now on the list of checks.
So apparently 8 Cycling is where the ecu is telling the injectors to dump more fuel every 8 revolutions of the power stroke causing it to run rich. One of the reasons Mario tested the voltage to the ecu as I have replaced the voltage regulator (the old one was causing voltage drop) and I am now running a Lithium battery.
iansoady- Sorry there is no going back hahahaha. The air box and intake fittings were damaged by the previous owner when the bike was dropped. I agree, the current fuel map is not ideal for my set up. So Mario the magician tried a Power commander to over ride the ecu and adjust the fuel mapping, made no difference. This is what lead him to think maybe the ecu is faulty as it appeared not to talk to the power commander.
Gianni- There may be something in what you said about the fuel pressure relief valve. Originally it was screwed directly to the underside of the tank. I had to remove it and retro fit it as an inline fitting to work with the Suzuki tank. Visually it inspects ok but I haven't put a fuel pressure gauge on the system to see if it is actually working correctly.

My to do list after chatting with you fine gentlemen.
1. Check Fuel Pressure/ Regulator function
2. Study FI Manual as provided by Gianni (Many Thanks!)
3. Check Fuel injectors for leaks and spray pattern.

Should the above not resolve my issue I was wondering if smaller volume injectors might work?
If I cant increase the Air surely this would reduce the fuel in the equation? 
         
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Guzzished Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2021 at 17:00
Good points Gianni and Brian, and things I was wondering about cos I have another 1100i that will have to be extensively rebuilt due to condition and won't be going back together as original, slight remodeling, the air box will have to go to make space for the suitcase sized ECU to allow remodeling of seat and rear end, (not going the cafe racer route though ) and I was wondering about relocating that ATS, also on this bike there is an ambient air temp sensor mounted to the top r/h frame rail under tank.
Good point re engine temp sensor fooling ECU.
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