Hi all, After a recent belts and other major service we have an issue with the right hand bank running extremely rich. It's recently also had all new pumps, return lines, pressure regulators and injectors. We are not getting any fuel pressure coming to the fuel pressure regulator. The car is an EU model. 1991. We've tested the temperature sensors and getting the right values. There are no air leaks. But we're not able to achieve the correct vacuum for the right bank. We've checked, tested and plugged all possible hoses and verified there are none we can find. Been through this before many years ago where we had a faulty by pass vacuum valve. Those are both OK. We have tested the protection relay and it's fine. Fuel pressure to the injectors and cold start injector is 80psi. We've checked the fuel return line is clear, which it is. We've changed the new pressure regulator with another which we know is working just in case. No change. I can swing the mixture using the mixture screws but it's not making any difference to the rich running. I use a professional wideband so we can see it's changing. We also checked the throttle plates, microswitch etc. Everything seems as is should be. Oddly the car fired up at one point ran a bit rich then since has been like this. The car was running fine before the fuel pumps stopped and the major service was done at the same time along with many other items as I plan on keeping it for a very long time. Its been 11 enjoyable years so far. Any information on where to look next would be appreciated. Thanks, Craig.
Does this mean that when you run the fuel pump on the bank with the trouble (engine not running), you get no fuel coming out of the return pipe #29 from the fuel pressure regulator?: https://www.ferrariparts.co.uk/diagram/ferrari/testarossa-tr-90/011-fuel-distributors-lines-ke-jetronic-system The supply fuel pressure needs to measure the ~5.5 bar and at least 1L of fuel needs to come out pipe #29 in 30 seconds in this test (see page D38 in the TR WSM). Until you can pass this test, the engine really can't operate correctly.
Hi Steve, so we're getting no where near 1L out of that return pipe. We get around 10%. There is a lot of air coming through it too.
As a further update. The car is idling OK now that we have pressure exiting the FD and fuel regulator. AFR in both banks is good at idle. When we open the throttle the right bank again goes rich. AFR 9.5. The left bank is perfect.
In open loop I can swing the AFR back and forth at idle. In closed loop the car is trying to lean itself out and the AFR shows this too as it varies back and forth. I would put all this in one post but I cannot see how to edit my previous posts, seems like the edit button has vanished.
Not great (and is the pressure in spec?) -- maybe one of the braided hoses has collapsed internally, or were those replaced as well? When you run the fuel pumps manually and individually without the engine running (by jumping the fuel pump relay socket 30-to-87) do they sound about the same or does one seem to be "straining"? Measuring the current that each fuel pump draws also might indicate something if one is much higher than the other. "Bleeding" is not required so just needing to do something special there is a sign that something is not right. The "edit" button goes away 20 minutes after posting so all you can do is make another post after that time elapses. (Or you can "report" your own prior post, and ask a Moderator to make a small correction, but just for small very-needed corrections -- not to do a big edit/addition.)
Hi Steve, Yes the pressure is in spec. We will check the hoses for issues, the braided hoses were not replaced. We will measure the fuel pumps current too. When we jump them they sound the same. Thanks for letting me know about the edit button.
Hi Steve, We did indeed have a small kink on the pipe. We've now sorted this and are getting 1.1L from both returns. We have now the car idling almost perfectly. However it will not take any throttle. When we press the throttle the car missfires on both banks. I initially thought its just a tuning and balancing issue. We found FD plate on bank 1 to 6 is working as it should however when the car is running and we press FD plate on bank 7 to 12 nothing happens. It was working fine last week. We're at a loss as to why it would now be acting this way. We double checked a few things today also: Resistance check across the pins for the tempreture sensors @ 70degs = 500ohm. We also checked pin 21 to 2 on both ECUs and had the same readings. 12+ volt check on the Y coolant pipe red wire and we have 14+ volts - Pass Lambdas are giving normal readings when in closed loop at idle. When open loop the Lambdas correctly read rich when applying throttle. Our Innovative Motorsport wide band sensor also detects rich running when we try to apply any throttle. It goes from AFR of 14.2 at idle to AFR of 11:1 in bank 1 to 6 amd AFR 10:1 in bank 7 to 12.
This is OK, but, just out of curiosity, do you have the later smaller 52mm diameter fuel pumps or the stock 60mm diameter fuel pumps. IME, the stock 60mm fuel pumps have more margin here and are more like 1.3~1.5L. Welcome to the (un)joy of Bosch CIS that has a bunch of very small orifices that can get blocked so easily on (rather unused) 30~40 year old cars. My suggestions would be to do 2 things: 1. Measure the volume of flow in the small line going from the fuel distributor lower chamber back the the pressure regulator when the fuel pump is running as described in this prior figure: Image Unavailable, Please Login A bit fiddly because the port on the pressure regulator needs to be blocked when the hose is removed to collect the fuel. If the flow is low (vs the expected 130~150 cc/min) = indicates that the orifice at the exit of the lower chambers is blocked = increases the lower chamber pressure = increases the upper chamber pressures = reduces the pressure difference across the slits = reduces the fuel flow to the injectors. As a sanity check measure both banks for this. 2. Do the Dixie Cup test measuring the actual fuel flow coming out of the injectors for three locations of the airflow metering plate (the idle position, a mid position, and a WOT position): Image Unavailable, Please Login Good Hunting!
Thanks Steve. Really apprieciate the help. All I know of the pump is that the part details. I'm sure the sizes are including the rubber surrounds etc, so I'd assume its the small diameter one. This was the part number verified by Bosch for the car. Description: FUEL PUMP Bosch 0580464125 Height, mm: 68 Length, mm: 216 The regulated specs on the supply and return line on your diagram are on spec. I'll check the lower flow rate in the morning when I get there. It does seem to be very much over fueling rather than not enough fuel getting to the injectors.ujCE
Yes, that's the smaller 52mm diameter body CIS fuel pump. Less iffy on a TR supplying 2.5L of displacement versus a 328 supplying 3.2L of displacement, and yours seem to be from the middle of the population's performance so all OK (i.e., they meet the required spec). Often the "dimensions" that a parts supplier gives is for the outside packaging so not so useful except for shipping. I'm not sure that I'll believe this yet . O2 sensors are design to detect things in the hot exhaust gas stream from a cylinder that is actually running. If a cylinder goes so lean as to not have combustion, I'm not sure if the signal from an O2 sensor is valid or not. At 11:1, or 10:1, a cylinder should still be running strongly -- even if your cats have set the coachwork on fire.
You can try blowing backwards up the hose to clear the lower chamber orifice, but, even if that works, the debris could "refind" the orifice and block it again. If the debris is "dissolvable", and you can get it cleared, that's where running some of the Techron Concentrate might be beneficial. These orifices are small -- like .008" diameter or maybe .010" diameter, IIRC.
Steve M, you may have seen this from me before as the way I got the lower chamber flow going with your insight. Craig, search “Do fuel distributors just stop working???” discussion in this “Boxers/TR/M” section started by rpissm, May 22, 2021. It contains a couple of Steve M’s quotes. I found them helpful when my 7-12 bank was not running after an extended restoration / maintenance outage on my 1986 Testarossa. QUOTE: … you also need a pressure difference between the upper chambers and the lower chambers of the fuel distributor. … if that orifice is blocked … the lower chamber pressure will not be lower than the upper chamber pressure … QUOTE: … it's absolutely critical for proper KE-Jet operation as fuel has to be able to exit the Lower Chambers to create the Upper-Lower pressure difference to eventually get fuel to flow thru the FD slits. ... I started up the TR with everything in place. Because my hands are too big to get in and around the fuel pressure regulator to reliably disconnect the small black plastic fuel return line where Steve M recommended, and I did not want to remove the manifolds again, I decided to simply disconnect the small black plastic fuel return line at the fuel distributor instead. I plugged the loose banjo fitting with a M10x1.0 x20 hex bolt with nut and crush washers to prevent any fuel pressure regulator backflow instead of Steve M's approach as shown below. Image Unavailable, Please Login Image Unavailable, Please Login I used a banjo eye fitting for rubber hose and pushed on about six feet of vinyl tubing. I connected it with the original banjo bolt to the fuel distributor as shown above. Image Unavailable, Please Login Image Unavailable, Please Login I stuck the other end of the vinyl tubing into a container to measure the requisite fuel rate per minute. Running the engine with BG 44K in the fuel, I found no return line flow and feeling the 7-12 exhaust manifold it was cold, while the 1-6 exhaust manifold was hot. I connected my small Mity Vac to the open end of the vinyl tubing and pulled a little vacuum in the line, but not much. I started to see a couple drops of fuel exiting the FD, and then a very small stream started. I was just happy that the internal surfaces and the orifice were seeing a little BG 44K solvent. The flowrate increased to 30 ML per minute, 40 and increasing. The 7-12 exhaust manifold temperature increased from cold to warm and increasing. EDoug
Probably did, but I can't even remember most of the stuff that I post . Can you (or anyone else who has made this measurement) confirm that when things are working correctly the flow in that small hose is in the 130~150 cc/min range? It's a value that Larry Fletcher (CIS Flow Tech) graciously shared with me when I was having a problem, but I'm a little unsure if it was 130~150 cc/min or 130~150cc in 30 seconds (and I sent my TR records along with my ex-TR).
Steve, once I established a little flow, I put everything back together with the intent of letting the solvent do its thing. If I need to be in there again, I will take a measurement for you. Maybe Craig has some current input here? EDoug
Thanks for the additional info Edoug. We're still not any further forward. We've tested the FD flow from the lower small return to the port on the EHA and found we can pass air to through it. We've also tested fuel coming to the EHA and confirmed this is also present. However what's not happening is that fuel is not passing through the EHA to the lower chamber return. I've been on a call with Larry from CIS flowtech last night. He also suggested unplugging the EHA and seeing if it then would flow but it didn't. So looks like I've needed up with 2 ceased EHAs. But I'm probably going to just send the FDs and EHAs to Larry to fully check and rebuild them either way.
did you swap fuel distributors to see if the problem transfers to the other side? Only takes like thirty minutes to do that.
Hi all, Thanks for all the help so far. As an update the car now runs well. The EHAs were the issue. One was slightly blocked and the other completely blocked/stuck closed. Once they were sorted we got 160cc through them as per Larry's guidance. The car now has a bit of a cold start issue so I'll dive into that and find out what's happening.
Hi Steve, I think it was 30secs. Sorry but I cannot exactly remember. It was in the middle of the night due to the time difference with him and I.
Craig, can you give any specifics on how you "sorted" both of your blocked EHAs? Unclear if Larry was suggesting that you solvent clean the EHA internals or whether he was suggesting unplugging the EHA electrical connectors as a diagnostic step? Thanks, EDoug.
Hi Edoug, When testing each section from the fuel regulator we tracked the issue back to the EHA as the fuel was coming to them at full pressure but not passing through. The EHAs were removed and soaked in cleaner over night. We then passed compressed air through them in the correct flow direction and they were cleared. We did this a few times and then reistalled them and achieved the correct flow rates out of the small return to the fuel regulator.
