Hello all, I'm a frequent lurker but rare poster. I'm thinking about getting into the Testarossa market. I currently own a 1981 DeLorean which has a Bosch KJet mechanical fuel injection system similar to the TR's. Mechanically speaking, most DeLorean owners would call KJet the Achilles heel of the car. Many owners have gone EFI or carbs just to be done with it. Is the Testarossa KJet something that should give me pause? Do owners here find that the KJet system is something that always needs tinkering? Am I crazy to even compare CIS on a DeLorean and a TR?
A properly set-up CIS injection system is trouble free and very reliable. Trouble is, so many of them have been messed with that it can take a considerable amount of time to set back anywhere close to as when new. That said.. PARTS...these are getting very difficult to find. Bosch no longer supplies any major components for these systems. Yes fuel pumps and injectors are still available, but warm up regulators, fuel distributors, and even some accumulators are no longer manufactured. Eventually many owners maybe forced to dump the system and install a port injected system and with that comes a considerable investment.
It is true that when the CIS system is working it works really well. But as it was also said, if it's been messed with it can be a project to make it right. A tech familiar with the system and possessing all the correct test equipment should be consulted. There is a Ferrari CIS manual that was published for the 400i that is very in depth and specific to the Ferrari 12 cylinder CIS system. I'll disagree a little about parts. The CIS system was used on a myriad of cars (think two Porsche systems) back in the day. Because of this, parts are still available. The Bosch Warm Up regulator (NLA) is a crucial part in the system can be rebuilt by a fellow in Alabama who's got a great reputation. Fuel distributor parts are readily available in kit form, and the fuel pumps and accumulators cross to VW parts. The time temperature probe (NLA) crosses to a Jaguar part if you can find one ;-).. The system is one of those systems that: "If it ain't broke, don't fix it" type systems. I've been told that unlike electronic systems, the CIS system is a limp home system. As long as there's fuel pressure the engine will most likely run and get you home. Hope this helps a little. As always, I'm open to corrections and/or suggestions re this subject.
A clean K-Jetronic with fresh pumps, new fuel & filter, airtight vacuum hoses and brass injectors is absolutely trouble free. I spray small amounts of silicone grease into the connection of the vacuum lines on the regulators to keep the inside form drying.
The Achilles Heel of any Bosch CIS system is extended disuse -- just way too many close mechanical fits/small clearances/tiny openings that don't tolerate fuel varnish/deposits well. A CIS system with a history of good performance of recent extended use wouldn't scare me, and, conversely, a long-disused garage queen, even if running OK at the moment, has some risk of developing issues -- BTDTGTTS . JMO.
Great points! And IF the car is going to sit for prolonged periods, I'd spring for the $$ and fill it with good ol Sunoco 260. It has a shelf life of 2 years and is made for these applications.
Sounds like wise words Steve. If you have indications of fuel supply issues do you then generally recommend to take the CIS distributor apart for ultra cleaning and resealing with new o-rings and main seal gasket? Best, Peter
Certainly, if you have an uneven fuel delivery problem, as measured by rotometer, or the "Dixie Cup volume X time", test at the various power levels = no choice but to clean/rebuild the fuel distributor. However, I wouldn't clean/rebuild unless flow rate measurements prove that it needs to be done.
As a less well equipped, experienced and skilled amateur mechanic I'd try the following before disassembly: - connect a can of pressurized carburettor cleaner instead of the fuel delivery line - move the pressure plate up and down while releasing the solvent This is cheap and easy to do. It may even solve the fuel delivery problem . It did for me on several cars. K-Jets have internal tolerances of 4/100 mm. Very scary to me when disassembled. PS: never forget to look inside the brass filter at the fuel delivery line. It often gets dirty and thus reduces flow volume inside the distributor resulting in uneven fuel delivery.
Sorry I'm lazy: I do it with everything installed in the car. Just pull the fuses for the fuel pumps and disconnect the delivery fuel line at a convenient location. (Why not clean the (hopefully brass) injectors, too?) If you have a second person turing the starter key the carb cleaner will be used as fuel. That's an optional step on K(onstant)-Jets (on controlled injection systems it's mandatory, otherwise the injectors don't open). The start will be delayed without a running engine as the spark plugs get wet. A fully loaded good battery will bring your engine back after some time. No need to remove the plugs. Carbcleaner vaporizes much faster than fuel. One could theorize that the carb cleaner sprayed into the cylinders may do harm. I've opted to ignore this theoretical possibility. PS: I buy Mannol Carb Cleaner on Ebay. It's darn cheap (<10 EUR/l) and does the trick. PPS: I didn't invent this procedure: lot's of youtube videos show it.
the debris getting loose in the fuel distributor will not always go through the nozzles and may be they get closed
Agree. It's a gamble to a certain degree. The way I look at it: the "debris" or "gunk" inside the distributor is made up of dried fuel residue. The carb cleaner acts as a solvant and dissolves it. On my car this has been fine enough to be sprayed through the injectors. This process has been used to clean the injectors on other cars by many folks. I think it's an acceptable risk. A big piece of debris will just take longer to dissolve... ... it may turn out different on different cars.
Ok, interesting way to try to cut a corner and clean out distributor junk without tearing everything apart. Just one question; do the engine actually run on the carb cleaner or do you pull the spark plug caps and just offload the cleaning fluid into the cylinders for later evaporation? If the engine is running you could do one side at a time and let the opposite side run on petrol? Best, Peter
Yes the engine runs on carb cleaner. On K-Jet cars I've never asked my wife to start the engine and I've never pulled the spark plug caps on any car. I don't see the benefits of doing so. Am I missing something?
