Mech

The motor will only get power momentarily when needed, and only when told to by the ECU and/or PS sensors and computer. If there are any faults the PS shuts down.. I wouldn't be expecting power or any action out of the PS unit. If you find the two CAN wires on the PS unit you could unplug them and put an ohm gauge on them and you should get about 60 ohms.

Yes the build up in the carb can effect their running. The drilling that the emulsion tube fits in, the emulsion tube being the long brass tube that holds the main jet and that the slide needle goes into, if that drilling gets crud in it, it effects acceleration and from about 1/4 to 7/8 throttle.

Did you notice that they didn't have that diaphragm on the bottom of the bowl ? Would that make the difference between fitting and not fitting ? I'd suggest sending that carb that doesn't fit back, and cleaning the old carb. Unless the idle mixture screw is seized in, or there is huge amounts of play between the slide and body, then it will be the best option.. the aftermarket carbs hardly ever run right without some adjustments and work anyway.

I think the power steering will be speed sensitive(the book will say), and that being the case it will be controlled by the ECU which has the speed sensor going to it. If there is a fault the PS system shuts down. If either CAN wire broke it would stop operation most likely, but should set a code saying the CAN was broken. You aren't getting codes.. So.. Check the ECU and the PS are getting 12v at all the places they should be. Study the wiring diagram carefully. See the dash has two power wires, one permanent and one switched. The ECU has several power wires, some permanent power and some switched, and it will have several earths as well I think. The PS unit has two power supplies. #31.. Might be a test port. It might have a can siganl.. Don't try to power it or earth it.

The wiring diagram shows two plugs on the PS unit. One plug has two wires, one power and one earth. The other plug has three wires, one power and two CAN communication wires. The power wires should have 12v and good earth, the other power should be a switched 12v(tested against any earth),and the CAN wires will I think be about five volts. I think also the way to test the CAN wires will be to use an ohm meter between them and you should get about 60 Ohms.

I'd check the voltage at the PS unit though, with the wire plugged in, and with the steering turned to hard lock, watching the voltage drop.. Just having enough power at the plug to run a multi-meter doesn't necessarily mean there is enough power there to run a motor. People get caught out by this all the time. You need to check for voltage to a unit, with a bit of a load on the circuit.

The diagnosis does seem to be that the unit is crook. Given the circumstances it's possible/likely that it's blown a diode or some other electronic part that can be replaced. I'd take it apart and remove the electronic board/unit and see if I could repair it. If it's old fashioned electronics with the components soldered through a base board, it's likely to be repairable. If it's the new surface mounted components then I'd doubt you'll get anyone to fix it. If it's the old through board style electronics you'll probably see the blown component and someone will be able to find a substitute, hopeing that it's only the obviously blown things that are crook.

https://www.partzilla.com/catalog/suzuki/atv/1991 There are four 1991 quadrunner's listed, and several models of carb. Some of the carbs are similar to that one you have except they don't have that enrichener valve that hangs off the bottom of the bowl. Check carefully though because there are several different jetted carbs, each for a different market, for different fuel, altitude, climate and possibly engine. It appears your carb isn't availiable, but, if you identify your model bike, then choose the correct carb in the listing and double click on the part number, it will take you to a page where, if you scroll down a bit, you will find a list of all the other models that carb fits. One of those other bikes may still have it's carb availiable, or you google search for the original part number for an after-market carb.

There's a Hisun Forge 750 owners manual in the downloads section here, that will probably explain how to do it.

Do a google search for "hisun 150cc 2006" and see if you can identify it, who sold them, and try to find an assembly manual.

That says it's a 2006 model.

Well it's made by Hisun, but Hisun don't market any models called Raptor, or of 150cc. I can't make out the stamped digit's shown in the photo, but that should confirm the year and might provide some other clues. If you can identify the bike from photos online then you may be able to get an owners manual, or assembly manual, which may have a wiring diagram. I doubt we will find a service manual that will talk us through the diagnosis process or tell us what readings we should get when testing with a gauge.. Try to identify the model and who sells them, then go looking for an assembly or owners manual..

Test it from cold, see if it backfires cold.. Warm it up and while it's warming get a rag and jamb over the exhaust outlet so you will hear leaks up at the head. Check the choke operation, make sure it's going right off down at the carb, pull the plunger out by the cable and let it go making sure the plunger snaps back in against it's stop. Adjust the idle mixture in and out making sure it makes a difference both ways and finding the best spot, and do it at a low idle speed. Then check for backfires.

No trouble. We all need a hand some times.

I'd double check all the fuses had power and continuity too..

I found the right manual at last. The later models don't have the diode in the fuse box. This should be your wiring diagram. There are three places the permanently live red wire from the battery goes to on the fuse box, one of which is the EPS fuse then to the EPS relays live terminal, and the other two go to main and memory fuses.. If the battery had been momentarily connected backwards, the EPS fuse and relay's live terminal should have been a dead end circuit with no current flow. The reverse battery shouldn't have hurt things in the EPS circuit as long as the key had been off. If everything else is still working then it would seem nothing else has been damaged either. I'd check those three wires going from the EPS to the diagnostic and the dash for continuity using the beeper on my gauge. output.pdf

Neither the PS unit nor the control unit can log a code if the fuse or relay that supplies them with power is disconnected, or if the earth's disconnected, or if the units are unplugged. Shadowace had disconnected something earlier and got a code so it is working. Shadow, what does the writing say under those two fuses ? I can't quite make it out. And if you pull those fuses, does it disable whatever they are labeled as ?

Is everything else on the bike still working ? Fan, lights , charging, gauge..

Thanks Gw. Ah well then Shadow, that starts to make sense.. lets hope it's only the diode.. Trouble is, if the diode goes it's meant to set a code. It may have blown something else, like obviously the PS unit or the control, or even the power supply module those things have.. We hope not. The diode is shown in that pdf as being in with the fuses and relays, third column from the left and the top two. They are both shown as diodes. Your bike appears to have fuses in there.. Check if they are blown. And.. you know how to test a diode huh ... One of the manuals I was reading said that all the relays in the fuse box are the same and can be interchanged. I'd try swapping the EPS relay.

You wouldn't think the flooding etc would cause a problem. I'm pretty sure that the decompressor will operate like most do and not force the valve open, but only hold it open after the cam has opened it. Hard to see how that could damage anything. Good luck in there. They are good to work on. I'd recommend you get some "loctite master gasket" to reseal the top up.. Brilliant stuff.. Way better than silicon or anything else on the market. Clean, economic, doesn't block selves or filters, never leaks, doesn't harden till the parts are clamped together so you don't need to rush, and if you have it apart again the old stuff is easy to get off.

Oh, ok. Well I can't identify the make or find anything about it either. If you find a vehicle identifying tab with something like a frame or vin number on it, it may tell us something useful.

We need to bear in mind that this only developed after you'd changed the battery.. Right ? Or had it been playing up with the old battery ? I think I'd pull all the relays and see which one cut the power to the unit, then do the same with the fuses. That would confirm what was what. The fuse is lower center and the relay should be lower left. You did see that last pdf I posted ? Then I'd try and find that diode it mentions. It should be right top or second down. If the battery had been connected backwards for an instance it could have blown the diode, and when the old battery was low voltage that can cause excess current draw which might have damaged the diode. I'd check the kill switch carefully. It may be a double pole switch and one pole/contact might not be working. Most of that though should have set a code. About the only thing not listed as a code is a worn or stuck brush in the PS motor, though it may be a stepper/brushless motor anyway.. The common cause in cars when there is no code set is either that it's a mechanical fault, or the power supply or earth is the problem and at the instant it's occurring the computer isn't powered and can't log a code ! So... I'd check the 14.4v didn't drop when it got a load on it. To put an electrical load on the EPS unit you have to put some force on the steering. I'd do that and see if the voltage dropped right down, which would mean there's a bad connection in the power or earth supply( you have checked all earths ?), or if it dropped slightly which would indicate the unit is trying to work but perhaps the motor's brushes are stuck or worn out, or if it didn't drop voltage at all in which case it would mean there was something wrong with the control unit or the EPS electronics. I'd check for voltage drop at the EPS control unit too when it had a load being applied to the EPS

You should repair or copy the old wiring.

Any idea where or what the diode they mention is ?

Hmmm.. You're right. It's mighty hard to find the wiring for the EPS. It's shown in later model wiring where it was fitted by default but I wouldn't depend on those. I found this though... 2010_Power_Steering_Addendum.pdf