I have a 1990 subaru sambar s/c ks4 On the way to work this mourning I noticed when the supercharge light came on the truck lost power when i backed of the throttle it was fine as long as i didn't push it hard enough for the light to come on when i got to work i left it idleing and it died it was hard to start but i drove it to my mech. Does anybody have any ideas could it be the mass air flow sensor or throttle position sensor how do you check them? Thanks
Changed fuel filter puy some seafoam same problem when the supercharge light comes on it falls flat on its face .
what do you mean,, It revs up ok aslong as the supercharge light don't come on i will try anything i'm at a loss
i'm more a purist and have always stuck with natural aspiration... but what i know of forced induction would fit on a pin head, but i'll share it with you and see if i can help... and honestly this is just thinking out loud... please keep in mind the advice i'm giving is not vehicle specific but general and some, all or none of this may apply. superchargers run a belt... make sure there is still a belt there. make sure it has the correct tension. i would probably go as far as to make sure it's still spinning, start the motor and have a look. i'm sure it is or you would have a terrible noise if it were frozen up.. but you never know. check all your fuses, fusable links and relays. supercharges will force more air into the cylinders and when there is more air you need more fuel. there should be a sensor that detects the boost in pressure created by the charger and signals the fuel injection (it is fuel injected, right?) to increase the fuel volume to the injectors. if you don't have the fuel to add to the increased air being forced into the cylinders you will have a sudden LEAN condition... it's going to feel like you just ran out of gas... completely nose over like you turned off the key (sound familiar?). if this is the case there are a couple things you can do. first of all do a touchy-feely look-see all along the fuel system. look for any kind of leaks, cracked hoses, kinks or loose electical plugs. also take a GOOD look at ALL your vacuum lines from front to back and especially around the fuel rail and the intake manifold. my old cummins had a vacuum actuated waste gate on the turbo. if the system uses a vacuum/boost sensor to a vacuum actuated fuel control then a small hose that has come off could be your problem. if you go through all that and can't find the problem you might want to get a simple hand held vacuum/boost gauge that you can run into the cab of the truck for trouble shooting. if i'm not mistake the charger will run at "vacuum" or NEGATIVE boost untill it spools up and really starts to force feed the cylinders. if you don't see the charger run through that cycle from negative/low pressure to full boost (probably 10-14lbs?) then i would blame the charger for the lack of power. as i mentioned before that you may have the charger pressure and not the fuel to back it up, it could also the the opposite. the computer knows where in the power band the charger kicks and, in turn, feeds it more fuel. but if the charger has a failure of some sort the computer may be feeding it fuel that it hasn't got the air volume (or boost) to create the proper mixture for combustion. and this may be the case... if the computer is feeding it a lot of fuel it could be bogging down because an internal combustion engine needs only 3 things to run.. fuel, air & spark. any one of the 3 that isn't in proportion or time will throw it off and it will fall flat on it's face. if the computer is mistaken and feeding too much fuel without any boost it could be loading up your cylinders and causing it to die. or you could have a bad MAP (?) sensor (anti-knock sensor, oxygen sensor) something that lets the computer know how lean/rich the motor is running and let it adjust accordingly. ok, so enough rambling here... i know it's a lot of info, and like i said it may/may not apply to your vehicle... just what i've learned through the years... good luck and i hope just one tid bit i have shared might be of assitance.
Thanks for the tips its a big help, Mark I did find a small hose off i'm not sure if it goes to anything, on the charger there is three hoses together a bigger hose and a small one on top thats ok then there is one that going between the charger and the a/c compressor thats not hooked up to any thing i'm not sure if that line hooks up to the charger on the bottom or not the a/c line is in the way when its running it will rev up high as long as the supercharger light don't come on if i mash the gas hard enough for the light to come on it seems to run rich while its falling on its face
found vacuum line not hooked up I Found this vacuum line going from 2 boxes mounted on the bed on the cab side of the air cleaner going toward the supercharger between the s/c and the a/c looks like it connects under the s/c but i can't reach it why wold it go from way over there and not hook up i will have to undo my a/c line to get under the s/c here is some pics if some one can look at there and see if that line is hooked up i would be foever gratefull
Anybody have any suggestions checked air box ok, vacuum lines look ok, when i rev it up then punch it the supercharge light comes on and dies out it seems to run rich when it comes back to an idle after that I'm Lost
same problem here just installed the engine after a rebuild. starts and idles fine. go for a drive and all is well until i troop on it. no super charger light comming on indicating no boost. The light does come on on start up and flicks off so it is working. I belive i have a small vacume line crossed up some where. that line you show here is same on mine and goes no where. Can you take some pictures of the small lines on top of the engine specificly the 3 lines on top of the carb and where the 3 different lines on top of the Super charger go as I may have the wrong one on the smaller of the 3 nipples. Thanx
I took some pics the small line from the supercharger under those three lines the bigger one goes to this box does anybody knows what the box does it has wires going to it
no boost thanx That will help. picked up a low pressure gauge today so will do some tests for boost and see if i can resolve my situation and help you. on the three different size lines at the SC where does the small one go when it leaves the S/C? if you snap a shot of that it would help a bunch. with that i will check mine and see if I get the boost signal i need. From there I still think that line you show goes nowhere as is it the same on mine. I had the engine out once already last year and I remember that line not having a connection and the truck ran very well. I do need to know where the small line of the 3 on the sc goes to Thanx
please check mine be connected wrong in this picture so don't change anything yet, at the supper charger inlet elbow there are 3 differnt size lines. where does the smallest of the three line track back to,, does that small line have a small one way check valve about 5 inches down the line. I may have that line crossed with one of the 3 line that are the same size at the throttle body.
On mine the small line on the supercharger goes to the two boxes mounted on the bed by the air box you can see the boxes on my post {vacum line not hooked up} it hooks up on the bottom and the top line is the vacum line thats not hooked up i still can't fiqure out my problem
will check sorry, been away for a few days, I will check mine and do some boost checks and relay the info back earliy next week. Thanx
Could it be the mass air flow sensor or throttle position sensor the fuel pump is ok . how do you check them any ideas.and who has them if i need one ? i drove it to work this mourning and it was real muggy and it ran rough then in the afternoon it ran smooth still falling on it's face when the light comes on . i'm getting pretty good at taking it easy Thanks
Has any body worked on or cleaned or replaced there mass air flow sensor i think thats what i'm going to work on this week
Under your dash are 2 plugs that are unplugged. They fit into each other. By plugging these in, it puts the truck into diagnostic mode. Your check engine light should begin to blink. These blinks can help you troubleshoot. Plug it together and see if you get a code.
found it the small line that runs from the intake maifold to the boost sensor box located at the back of the box below the tail gate was pluged. there was no boost signal to that box. that line also tees off and goes to the clyinder head, open the rear engine access door and you will see a small black box with a couple of wires and that small rubber signal line attached remove that line and check for blockage. If that line is Ok that box may be suspect.
It's been 5 months and i still don't have this thing fixed replaced the supercharger,map, coil,charger valve, next i quess will be the distributor
One more try. i'm going to replace the distributor and if that don't fix it I'm going to part it out to try to recoup the $5500. for the truck and the $1000. dollars in parts I tried to fix the thing with I'm Pretty upset about it . I like the truck It's fun to drive from what I can remember It's been a while . Sorry guys I just needed to vent and it could be the dist. and i would be happy again a if anybody has any ideas let me know I thought about making a Japanese horse drawn Buggy for my horse but my horse weighs more nthan the truck. Thanks, Mark
my s/c light does not come on.how can I tell if it is working or not.it seems to have lots of power yet.thanks.where is the light too.
After all this time My truck is running Yeah! can't believe it, Somebody pinch me . Turned out to be the distributor
my supercharger has idling up and down, after drivin about 5km clutch temp light on cane in dashboard, and ECVT slow down and burn odor came. later only idling no rpm, and only engine check light come on !!
