My LJ Tech buggy has a problem in the EFI system. I can't find a wiring diagram for the EFI system and apparently LJ Tech is out of business.

I wish I would have bought a carbeurated model now but I have what I have now so I need to fix it.

I have downloaded the manual for the Joyner 800 CC but it is not the same system so the diagrams are not the same it is of some help but I need the right one. The EFI system is Bosch but it has no test port that we can find. The Joyner EFI intake is different (the intake faces to the rear of the engine mine faces the front)the fuel rail is different (Joyner does not have a regulator on the rail mine does)and the connector to the ECU is different (the Joyner has 4 rows of pins and mine has 3). I am not sure if my system is the same as the Roketa or not. Is there any info on the Roketa EFI system out there? The PDF of the 800CC engine on this site does not show the EFI system.

From reading the manual for the Joyner we have concluded the system is running in the MIL or limp mode right now. This makes the ECU work and the buggy run but it runs in a very basic mode and is designed to not leave you stranded. The HP in MIL mode is very low and runs the engine rich it also makes the engine idle very high because it does not take inputs from many of the sensors in this mode.

Do any of you have any info you can share on this system?

Just for the record I have already rerouted my return fuel line into the tank and gotten rid of the "T" fitting. I have changed all the fuel lines and added a filter before the pump and replaced the filter between the pump and the fuel rail. I have removed all the injectors and cleaned everything out I have pulled the regulator apart and cleaned it. The engine does not apear to have a vacum leak it is pulling about 15"-18" at idle (1500 RPM). I do not know what the fuel pressure is I have ordered a fuel pressure gauge but it has not arrived yet.

I am thinking very seriously about an engine swap if I can't get some info on this thing and get it running properly. What is my engine worth? It has about 5 hours on it there is nothing wrong with it other than the EFI issue. Compression is 155 Lbs across all cylinders.

Thanks for any help you can give.

P.S. My son just got off the phone with Bosch I think they are going to fax us a diagram. I hope we can fix this thing it has not ran correctly since new.

Mike

Bosch was a dead end they told me the ECU was made for a company called Qinchuan (BYD). They have no info they make the ECU for these companies to their specs and you must contact that company for any information. they said it works the same for all auto manufacturers they build parts for. I have sent that company an email but who knows if they will have the info or even respond.
Mike

I have bms 800 and had same problem. Water got in throttle body sensors, just take them out and clean them good and also I had did the same as you and put fuel filter before fuel pump, it will work for some time then its no good! fuel pump went out felt like a vapor lock. hpoe this will help you out.

Call Sean at superkarts.com or minibuggy.com. He was and is the owner of LJ tech and he will have all the diagrams and specs you could possibly need. Van

Gundog,

I don't believe Sean goes on MB.net anymore, the LJ website is gone, but the SuperKarts web page is still available at:

http://www.super-kart.com/

I talked to Sean today on the phone he was a lot of help. The problem I was having is common according to Sean.

The ECU was not in Limp mode at least I don't think it is. There is a solenoid type valve near the intake of the EFI body it has a rod that runs in and out of a hole that allows a huge vacum leak and speeding of the engine. He said that they have had this problem for some reason the ECU needs an input from another sensor that does not exist in the system. My guess is it has to do with the A/C for the car this stuff fits.

What needs to happen is the rod needs to run in and plug the hole to lower the idle when the A/C compressor kicks on the rod runs out a little and the engine speeds up. Well there is no freakin A/C on the buggy so this thing seems to have a mind of its own. This causes irregular idling sometimes after a hard run it is at 4000 RPM at idle and sometimes it is 1500 RPM. The good news is the fix is quite simple.

Remove the air cleaner Inside the intake port above the butterfly there is a hole get a 1/2" vacum plug and poke a very small hole in the end of it. Force it into the hole and the idle will drop way down then you can adjust the idle with the idle adjustment screw. My buggy would never idle under 1500 RPM now I can slow it way down to 700 RPM which makes it much quiter at idle.

I don't know why this idle solenoid works the way it does it should close off the hole at idle but it does not. The solenoid is operating and works every once in a while. I replaced the solenoid and it did the same thing so for some reason something in the system is opening it up at idle. From what I can see it is not needed for the buggy anyway so mine is plugged. Basically with the hole open it makes a huge vacum leak.

I have not ran the buggy since the fix other than running it on the trailer. I will go out next week and trail test it some more.
Mike

Seans website to sell his buggies is [url]minibuggy.com[/url] his american made buggy is at super-kart.com. His e-mail address and phone number is on both.

His LJ tech site is www.minisandrail.net

I found the one on minisandrail.net...Glad you got the help you needed GDog....by the way that SR-2 CVT Sand Sport on the minisandrail page is completely bad I can't spell!