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Fuel Injection woes.

Printed From: guzziriders.org - moto guzzi forum
Category: Modifications and Restorations
Forum Name: Modifications
Forum Description: Let us know all about your Guzzi related modifications
URL: http://www.guzziriders.org/forum_posts.asp?TID=13707
Printed Date: 18 Jan 2022 at 22:08
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: Fuel Injection woes.
Posted By: INSTG8R
Subject: Fuel Injection woes.
Date Posted: 28 Jun 2021 at 05:09
Time to ask the brains trust as my googling and forum searching have branded no results.
I have a '99 California EV Café Racer project (sorry purists). Before work began it ran smooth as a Big Guzzi twin should. After pod filters and exhaust mod's she is not so smooth. I have had a custom 45mm exhaust made with crossover and db killers fitted. 
I expected it to run lean but I have quite the opposite.
Local Guzzi mechanic has set the Fuel Injection, tps, throttle controls, to factory settings but she still is not happy.
Idles nice, accelerates ok up to 1/4 throttle then gasps for air as it chokes on too much fuel. Black smoke and some coughing and banging ensue.
When trying to cruise over 1/4 throttle it surges. The mechanic who set it up said it is 8 Cycling, whatever that means, and couldn't work out why. All sensors tested with in parameters and the only thing left to test was the ecu, however the only way to test that was by swapping it our with a known good working one, which no one has.
One of my questions is will screwing the idle/air mixture screw out on the throttle bodies lean the fuel mixture out? and if so should I use a manometer when adjusting to keep the balance true?
Any other suggestions would be greatly appreciated.

The bike in question. Still unfinished.





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INSTG8R



Replies:
Posted By: Guzzished
Date Posted: 28 Jun 2021 at 07:09
Instg8r
No idea what '8 stroking' might be,
Is there any such thing ?
If there is someone will chip in.
In the meantime, it's obviously a fueling issue, leave the ECU alone.
Your twist grip directly and mechanically opens the throttle butterfly valve feeding the engine with more air as it opens wider, the throttle position sensor is operated by the butterfly spindle/pivot turning but the position of the sensor on the spindle is adjustable, ( two little screws underneath )
Allowing the sensor to be 'advanced' or 'retarded' in relation to the butterfly position, if too far 'advanced' the ECU will think the butterfly is wider open than it actually is and will therefore provide more fuel than is actually wanted resulting in massively over rich fueling as if trying to run on full 'choke' on a carbed engine,
Do you have a manual with your FI set up described in it ?


Posted By: Guzzished
Date Posted: 28 Jun 2021 at 07:24
Plus, if I remember correctly there is a sensor in the original air box, and probably another under the tank on the original set up, what has happened to these, are they still connected, where is the one that was in the air box, (filter housing )


Posted By: Guzzished
Date Posted: 28 Jun 2021 at 07:27
I'll have a look at my manuals later when I get over to my workshop to refresh my memory and post again later unless you get some definitive answers in the meantime.


Posted By: Brian UK
Date Posted: 28 Jun 2021 at 08:04
8 stroking is when it runs very rich and can sometimes only fire every second firing stroke.

Guzzished, he said the TPS had been set to factory default.
Assuming this has been done correctly, it must be something else. The TPS woud have to be wildly out to get that much overfuelling.

Any adjustments to the throttle bodies in terms of idle mixture should always be done in conjunction with a manometer. However, the idle mixture could never be that far out to cause so much overfuelling.
Do you know the injectors are good, and not leaking/dripping?


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: andrewhush
Date Posted: 28 Jun 2021 at 09:29
Brother in law's recently acquired ballabio came with fuelling problems. Would start and idle, but very rich, stank of unburnt petrol. Would drive but not well. Turns out that the tps was not the correct type. Voltage from the signal wire varied upwards from 2.0v rather than from nearly zero. A new properly spec'd one and a standard setup sorted it.


Posted By: Guzzished
Date Posted: 28 Jun 2021 at 10:33
Right,thanks Brian,
INSTG8R, says it ran well prior to the stripdown/rebuild. So I was assuming TPS would be original and injectors OK ( Andrew ) not necessarily guaranteed but reasonable assumption I thought.
( Just occurred to me, is the fuel fresh, not been sitting in the tank for yonks )
TPS setting seemed possible/likely because I recently acquired a 1100i Cali of similar vintage to INSTG8R's that was having similar problems though not quite as bad, that was supposedly set up by someone who was supposed to know what they were doing which was cured completely when I experimented by resetting the TPS according to the 'superceeded', obsolete, instructions for resetting. i.e. loosen screws, twist against spring loading and release, tighten screws. Wasn't perfect first go but vastly improved, addition of very fine reference mark for further minute adjustment using sparkplug colour as guide to go richer/weaker, like adjusting carbs, followed by fine adjustment of balance and tickover, bike is now beautiful, starts on tickover hot or cold, ( just a 'whiff' of raise on the tickover lever when stone cold ) runs clean throughout at all speeds and loads, and seems to be achieving about 60 MPG With good plug colour, was going to buy a digital meter, ( always preferred analogue before ) and do it according to the numbers but am so pleased with it as is, that I haven't bothered.


Posted By: Guzzished
Date Posted: 28 Jun 2021 at 10:46
Thinking again, I think I've experienced 8 stroking in the dim and distant past, with stinking black smoke, coughing, spluttering and banging, and I'm sort of sure it was due to rotten petrol gone off in the tank.


Posted By: nickst4
Date Posted: 28 Jun 2021 at 10:57
8-stroking would be the logical term for a four-stroke that is firing on every other compression, just as 4-stroking was a very familiar term for a two-stroke that fired on every other stroke; something stinkwheels did/do as a matter of course during normal usage. All to do with needing a combustible mixture in the cylinder!

Nlck


Posted By: iansoady
Date Posted: 28 Jun 2021 at 11:54
I have to ask - if it was running well why make the mods? I would replace standard and see if it returns to running well. It does sound as though the air / fuel map is not compatible with your current setupand to properly correct that you would need to change the map in the ECU but I have no idea whether this would be possible on your bike. A dyno would be a good way to find out what is actually going on.


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Ian
1952 Norton ES2
2008 Yamaha 250 X-max


Posted By: Gianni
Date Posted: 28 Jun 2021 at 12:32
Guessing here but how about this for an explanation...

You have replaced the air filter box with pod filters. The air temperature sensor (ATS) is now either disconnected or hanging somewhere and, as a result, is sending mis-information to the ECU.

It is not essential that the ATS is mounted in the air filter box though that does give the most accurate reading. On the early Quotas the ATS is mounted in free air just behind the front frame down tubes.  However the standard mounting can mean it gets an overhot reading when stationary or at low speed due to the proximity of the exhausts so some owners relocate it up and away.

This Guzzi FI manual may be of use to you:  https://dpguzzi.com/efiman.pdf" rel="nofollow - https://dpguzzi.com/efiman.pdf

I would also check the operation and closing of the injectors and the fuel pressure relief pop-off valve.


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Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT


Posted By: Brian UK
Date Posted: 28 Jun 2021 at 16:05
Very good point, and also reminds me of the engine temperature sender. If that misbehaves (or not connected) it will also cause rich running as the ECU will think the engine is very cold.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: Guzzished
Date 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.


Posted By: INSTG8R
Date 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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INSTG8R


Posted By: Brian UK
Date 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.




-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: INSTG8R
Date 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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INSTG8R


Posted By: INSTG8R
Date 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 http://www.guzziriders.org/new_reply_form.asp?TID=13707&PN=2&TR=16" rel="nofollow -   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


Posted By: Brian UK
Date 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.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: Gianni
Date 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" rel="nofollow - 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


Posted By: Brian UK
Date 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.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: INSTG8R
Date 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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INSTG8R


Posted By: guzzwiz
Date 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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presently 850T3/1000cc, V50PA


Posted By: Brian UK
Date 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.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: Gianni
Date 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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Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT


Posted By: Brian UK
Date Posted: 04 Jul 2021 at 17:15
Increasing fuel pressure is a known tuning aid, but it has to be done with great control.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: INSTG8R
Date 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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INSTG8R


Posted By: Brian UK
Date Posted: 19 Jul 2021 at 08:12
Well at least you know the pump is giving good pressure.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.



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