A batch of fuel tanks fitted to Plus 8s in the 1988/1989 period have pickup points which could become "dry" when the fuel moves to the left under the centrifugal force created by a turn to the right. The symptoms reflect other possible problems with the fuel systems such as an intermittent fuel pump failure, improper ground or injection system problem. It can be maddening and the possibility of this problem should be quickly investigated. The solution is the fitting of new tank.
Hard to Start a 1984-1990 Plus 8 EFIi When the Engine is Hot?3.
When my car is reluctant to start, I merely run the pump for a few
moments and it will comply however, that is not possible with stock
setrups..whether Morgan or other cars using Rover/LR L-Jets.
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Hot Start Problem With Flapper Morgan/Rover V8s (1984 to 1990) Rover article This problem is common with Morgan EFI cars made from 1984-1990 using the Bosch L-Jetronic fueling system. It also afflicts otheramong TVR Griffith and Chimaera owners. It occurs when attempting to re-start the car shortly after it was stopped in warm weather (eg. when filling up with petrol). Many caused by Fuel Vaporization on Rover SD1 Efi Systems. Problem: Fuel vaporization can occur at the injectors when a vehicle with the engine at warm to hot operating temperature is parked in the sun for a short period and then restarted. Should a customer complaint of this nature be experienced, the followingaction should be taken. Solution: Provision has been made for the fuel pressure to be increased temporarily during engine starting and for a short period of operation after engine start-up. As this effect would be undesirable if it occurred at every engine starting cycle, provision has also been made for it to only apply when the engine is at a high operating temperature. The modification is accomplished by means of a solenoid valve installed after the fuel pressure regulator valve which restricts the fuel return line for up to 45 seconds after starting is initiated. This counteracts the sad effect of the fuel vaporization. At the same time, the fuel pump ballast resistor is by-passed, thus supplying direct battery voltage to the pump with consequent increased output.
Range of Vehicles: All Rover V8 electronic fuel injected models. This was dated January 13 1986 During the 1986 time-frame a similar bulletin was issued to U.K. Dealers but apart from a list of items found on the micro-fiche, no copy of the UK document has been found. In both cases, UK and Australia, Rover provided a “Hot Start Kit” for Dealers to fit to customer’s cars when complaints were received. The U.K. and Australian Kits were slightly different, as were the wiring loom changes for both regions, unfortunately, for the time being, neither of the supplementary circuit diagrams have yet been discovered, making direct comparison impossible. However, a comparison of the kit components clearly indicates that the U.K. and Australian solutions were essentially the sa me, in that they both used the same four additional active circuit components shown below but the Australian kit also included a made up addon to the wiring harness whereas the UK kit did not. The UK "Hot Start Kit" is specified on SD1 microfiche No.3 G03, under part number BHM 1620 and originally retailed at about £140. The four active components (not including brackets, hoses, clips, relay socket s, wire, etc) are: AUU 1028: Solenoid valve. DRC 1820: Relay (2 off). AUU 1029: Delay relay. Thus it has been possible to establish, from the Australian document, that by a combination of switched relays, a delay unit and a solenoid valve, the fuel pressure was temporarily increased when the engine was hot enough to require it, there by purging the fuel system and enabling the engine to re-start. Bear in mind, whatever solution Rover devised, it had to work seamlessly from the ignition key. A mickey-mouse fix such as those mentioned later on would not satisfy indignant owners who suffered this hot start problem every time the sun shone on their executive car just a two or three years after they purchased it. What is going on now? A forum question arose from a non-SD1 source regarding fuel vaporization and how it can prevent Rover V8 Efi engines from re-starting when they are hot, often when retro-fitted to cars with smaller engine bay dimensions like Morgan, TVR, Marcos. The same question has also arisen from time to time on SD1 forums and discussion groups with regard to original SD1 Efi installations. Clearly, all these years later, the intriguing problem still exists. As implied above, as engine tuning starys from a happy template, the problem gets worse. This EFI system can and does suffer from fuel vaporization, all the more so if there is restricted under bonnet clearance. When the car and engine stops, all the latent heat in the block is no longer able to be removed by airflow and the cooling system and the block temperature quikcly becomes very high, more especially in hot weather. The temperature of the plenum and the fuel rail. The area gets very much hotter a few minutes after stopping than it ever does under normal running and cooling conditions.This leads to the fuel vaporizing in the fuel rail and upon re-start, despite the pressure being controlled by the regulator, vapor is an expanded form of liquid, so the resultant air/fuel mixture will be much weaker than the anticipated air/fuel ratio of 14.7:1. Obviously when trying to re-start the car, the pump pushes in new, cooler fuel but it is still very hot under the bonnet and new fuel may still vaporize until it can carry some of that latent heat away. With fairly limited fuel flow all that trapped heat is not going anywhere until we give it some time and help by angrily lifting the bonnet, spend some time glaring at the engine, peer suspiciously at the engine, pull at a few wires, run around the car, yell at the wife and generally curse our luck for a few minutes. All this allows some of heat to escape into the atmosphere and allow the engine to catch. Sadly, this success merely encourages us the act the same way the next time. Sadly, AFAIK, there are few, if any, SD1’s on the road today with a retro-fitted with a Rover “Kit” in place and with no circuit diagrams available to enable better understanding of Rover’s solution, how might we deal with the problem if it occurs today? One expert suggests the following: Method: Lift the bonnet and wait. Use the accelerator pedal when re-starting to make the fuel flow faster and give a richer mixture. Run the fuel pump for a few minutes without starting the engine. On an auto try to crank the engine in drive, the pump runs but the engine does not turn. On a manual, disconnect the engine harness and try to crank the engine, the pump runs but the engine does not turn. Run your rad fan so that its continues to run after the engine has stopped. The Underlying Problem The Rover SD1 system should be able to cope with this condition but it sometimes does not - In a Rover's case, they put a large blanket under the bonnet as a noise insulator, it perversely also acts as a heat insulator. Only after some years, from new, when these problems became manifest did Rover design and issue the after-sale, dealer fitted, Hot Start Kits to solve the problem. I believe the main reason the problem occurred after a few years service is because the Efi system is probably not functioning correctly in other areas such as mixture, set-up, air leaks, electrical connection problems, component faults, etc. i.e. poor maintenance of the system in general (not surprising, as anyone who used franchised dealers for servicing will know, even today). When this happens it makes it more difficult to cope with the fuel vaporization abnormality. The real answer would be to check the system out thoroughly along with the electrical connections. While it is entirely possible to solve inherent problems using a scattergun approach, in the end a thorough analysis of the system is the best route to follow which can be achieved using clear guidelines, simple instruments and boring techniques. Rover Hot Start Kits So what is known about the hot start kits and how did Rover intend they should actually work? Despite the lack of circuit diagrams the basic principle seems to be as follows. As already seen from the Australian bulletin, Rover’s idea was to temporarily raise the pressure at the injectors by blocking the fuel return pipe using an electrically operated solenoid. The revised system also bypassed the fuel pump ballast resistor to maximize that effect. This brings to mind another of our school physics experiments to show that if the pressure of a liquid is raised so then is its boiling point. Thus, it stands to reason that if the liquid has already vaporized (boiled) and the pressure is subsequently raised, the vapor is now likely to return to its liquid state and will behave once more as liquid. With the pressure at the injectors raised to about 50 psi not only will the fuel try to re-liquidize, but the injectors, which normally operate at 28 to 36 psi, will pass between 40% and 80% more fuel each time they open, significantly enriching the mixture such that the engine should immediately fire and run. Then there is the question of how the system “knows” when to operate. The inclusion of a radiator temperature sensor in the circuit means that the engine has to be very hot before the high fuel pressure function is triggered, and of course the engine must be cranking, so it is reasonable to assume that as soon as the engine fires and cranking ceases, the system is deactivated and the fuel pressure immediately returns to normal. Clearly, Rover decided it was undesirable to over-pressurize the system too frequently, restricting it to occur only when the engine was very hot. Even so, they were confident the system could withstand the 50 psi designed into the solution without causing fuel leaks or damage to components such as the pressure regulator, pump and fuel lines. Summary The myth of fuel vaporization (sometimes called vapor lock) clearly does exist on the SD1 Efi and whilst Rover devised a method of dealing with it, the circuit diagrams have not emerged in the intervening years. However the Australian Technical Bulletin has materialized and it contains all the information regarding components, part numbers and specific changes to the wiring loom so any enterprising home mechanic could carry out the modifications an Rover Fix for Hot Start Problem. The Hot Start Kit is not longer made. But it can be done at home. Here is a pdf of their instructions. |
As most later LR/Rover Plus 8 owners realize by now, (or should) there are many variants of Plus 8s. You cannot parts source or advise others intelligently unless you know which variant is the subject of concern. If you do so, you can cause frustration, lose money and even cause damage.
In the case of their ignitions and fueling systems, overseas Plus 8s, after a two year period (1996-1998) when they were not shipped, largely followed the (1995-2000) system called GEMS. During 2000, Morgan switched all Plus 8s to that system and it became the standard to the end of the LR/Rover Plus 8 model line), though LR had moved onto the MOTRONIC system, which was never used on Factory-made Plus 8s. Confusing? Agreed. But it is key for Plus 8s owners as so many components were changed and different, though used simultaneously.
In the ignition and fueling areas, the differences are remarkable. If you are confused, feel free to write me, especially if you are in the UK.
If you buy from a LR supplier you are likely to pay opulently for the
wrong parts. If you buy from a Morgan dealer, it must be one in the
same country you are and someone who has been around during the era of
your car.
In
the ignition area, Hotwire Plus 8s in the UK (1990 to 2000 (both
transition years) had adjustable timing distributors while Overseas
Plus 8s used ECU-controlled ignition through 4 coil packs and a Morgan
bespoke fuel map. ALL Plus 8s (UK included) used Discovery 2 programming after 2000. Here is the wiring for a GEMS coil pack system below.