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Discussion Starter · #1 ·
After I ran out of gas suddenly the engine was running very rough maybe only on 5-6 cylinders. I replaced the fuel filter but not the pump as it was running ok. Can anyone help me on this? The injection system is a Bosch D-type.
 

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Idling rough, cruise, full throttle, across the board? Do you smell gas in the exhaust? A lack of fuel will usually mean no more gas smell that usual, but if it's getting fuel but no spark you should be able to smell it. If not smell it you should be able to feel it in your eyes but you kinda need to know what normal exhaust felt like because many older cars will burn your eyes anyway.
I'd try pulling plug wires one at a time to see if any individual cyls are actually not firing or it's just an iffy fuel delivery causing random roughness.
Could be fuel pressure I spoze, but idle vs load would help determine that. Like maybe the prefilter is clogged, which I've never experienced due to running the tank dry but rumor has it they can sometimes clog because of that. I guess the theory is it sucks up the last bit of crud on the bottom of the tank when running it dry, but I don't believe that for a second. I suppose, maybe, a big maybe, is some kind of crud is floating on the gas and when run dry it finally sucks that layer in and clogs it. What that crud/goo or whatever could be I don't know because I've never seen such a thing, just a theory I have. Full throttle will tell you if overall flow is restricted.
There should also be some kind of fuel pressure regulation, which is likely dumping excess gas back into the tank. If that happened to fail (dump too much psi) at the same time for some reason it would cause your problem. There should be a port on the fuel rail somewhere to measure psi but you'll have to google to find the correct psi.
If one or more cyls fails to fire consistently then I'd check spark first using a wire or something to let the plug wire jump to ground to see if it's up to par. You can also use a random spark plug with the approx gap you use while holding the plugs body to ground. You kinda have to know what a good spark for that car looks like though, or a good enough spark period. If spark is iffy then check the wires and distributor cap for the reason. If it has points they can cause issues if the gap is too far open or closed. The condenser can do it too but I'm just guessing about your car having points because I don't have a clue. Otherwise replace the plugs, or at least inspect them. If I bother to pull them out I figure might as well replace because no plug works better than a new plug so I change more often rather than spend $ on fancy ones or gimmicks. This is especially so with older cars because the more they pollute and/or burn oil, the quicker they kill the plugs. Or in some cases they kill one or two plugs, like the PCV system can cause that by sucking oil in and dumping into one or two cyls more than the others. If by chance you find that's the reason, let me know and I can explain a fix. Or if you just have the pcv sucking oil period, which odds are you do.
I'd also check the injectors which may possibly be clogged? Not sure how anything could get past the filter but who knows. Plus it's possible the filter element ruptured and let whatever crud through to clog them. Who knows why any of the above could happen but in my experience Gremlins make unrelated things go bad when something odd happens. So keep an open mind that it may not be related to running out of gas and simply happened at that time to mess with you.
Other things could be the plug connectors to the injectors or any other plugs relating to the fuel or ignition. Maybe one was borderline with corrosion or a wire nearly broken, then when you were in there changing the filter or whatever you touched it and that was it... You would not be the first to do that by a long shot, and the older the car the more likely it is to happen.
 

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Discussion Starter · #3 ·
Idling rough, cruise, full throttle, across the board? Do you smell gas in the exhaust? A lack of fuel will usually mean no more gas smell that usual, but if it's getting fuel but no spark you should be able to smell it. If not smell it you should be able to feel it in your eyes but you kinda need to know what normal exhaust felt like because many older cars will burn your eyes anyway.
I'd try pulling plug wires one at a time to see if any individual cyls are actually not firing or it's just an iffy fuel delivery causing random roughness.
Could be fuel pressure I spoze, but idle vs load would help determine that. Like maybe the prefilter is clogged, which I've never experienced due to running the tank dry but rumor has it they can sometimes clog because of that. I guess the theory is it sucks up the last bit of crud on the bottom of the tank when running it dry, but I don't believe that for a second. I suppose, maybe, a big maybe, is some kind of crud is floating on the gas and when run dry it finally sucks that layer in and clogs it. What that crud/goo or whatever could be I don't know because I've never seen such a thing, just a theory I have. Full throttle will tell you if overall flow is restricted.
There should also be some kind of fuel pressure regulation, which is likely dumping excess gas back into the tank. If that happened to fail (dump too much psi) at the same time for some reason it would cause your problem. There should be a port on the fuel rail somewhere to measure psi but you'll have to google to find the correct psi.
If one or more cyls fails to fire consistently then I'd check spark first using a wire or something to let the plug wire jump to ground to see if it's up to par. You can also use a random spark plug with the approx gap you use while holding the plugs body to ground. You kinda have to know what a good spark for that car looks like though, or a good enough spark period. If spark is iffy then check the wires and distributor cap for the reason. If it has points they can cause issues if the gap is too far open or closed. The condenser can do it too but I'm just guessing about your car having points because I don't have a clue. Otherwise replace the plugs, or at least inspect them. If I bother to pull them out I figure might as well replace because no plug works better than a new plug so I change more often rather than spend $ on fancy ones or gimmicks. This is especially so with older cars because the more they pollute and/or burn oil, the quicker they kill the plugs. Or in some cases they kill one or two plugs, like the PCV system can cause that by sucking oil in and dumping into one or two cyls more than the others. If by chance you find that's the reason, let me know and I can explain a fix. Or if you just have the pcv sucking oil period, which odds are you do.
I'd also check the injectors which may possibly be clogged? Not sure how anything could get past the filter but who knows. Plus it's possible the filter element ruptured and let whatever crud through to clog them. Who knows why any of the above could happen but in my experience Gremlins make unrelated things go bad when something odd happens. So keep an open mind that it may not be related to running out of gas and simply happened at that time to mess with you.
Other things could be the plug connectors to the injectors or any other plugs relating to the fuel or ignition. Maybe one was borderline with corrosion or a wire nearly broken, then when you were in there changing the filter or whatever you touched it and that was it... You would not be the first to do that by a long shot, and the older the car the more likely it is to happen.
Thanks for the reply Chevotya. Testing the injectors yesterday I found out that only 5 injectors are getting power. Is there a fuse or relay in that connection? Plugs are new, filter was new, no clogs anywhere.
 

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My guess is there's one fuse for all of them. I'd say that with 99% confidence but 1% you never know what weird things they do. I'd also assume that the controller is providing all that power and it gets all it's juice from one fuse. Probably through a relay that get it's power from a fuse. So if some are getting power then I'd assume it's not a fuse and the controller is the issue. Or wiring between the controller and inj. So trace wires to the source to look for something causing it. I use either a sharp probe on a multimeter to push thru the wires insulation, or use a pin or needle. That way you can check the actual wire in case the connection on the plug at the end is bad. If that conn is bad you simple take it apart and solder it. Sometimes it's a pain to get them apart and may damage/break it, or even need to cut it apart, but you can just use epoxy to put it back together. Usually you can buy replacement plug connectors for stuff like that. With multiple going bad at once I kinda doubt that's it, but if you were in there working on the filter or whatever it's possible you did something. Often times the inj plugs/wires are sticking up higher than most things in there and people set a parts box, tool bag, tray or whatever on the eng and the weight on the plugs/wires can be the straw for an ancient connection that was nearing failure anyway.

Meanwhile I'd research common failures/issues with that system because odds are the failure has happened to many people and someone has posted about it. And try to find a schematic for the controller. It's a pretty old system but I'd imagine they use transistors to control the injectors because relays aren't fast enough. Hopefully the controller is not epoxied together so you can take a look-c at the guts.
When I open up something electronic like that I first look for any burnt parts which should be obvious. Things like resistors, transistors, capacitors, copper traces on the board etc will be visibly burnt or have a burnt hole on it where the smoke got out. It's a goofy old saying with electronics "Don't let the smoke out", as if the smoke is the spirit of the part and once out it's dead ;)
I also look for any broken solder joints at the legs of those items. I find that is the case on a lot things where one leg to one item was simply not soldered good and over time it finally lost conductivity. Usually you can see it because the solder didn't flow nicely over the parts and freeze, but instead looks more like the leg of the part had non-stick teflon on it and the solder did not flow. Often you can wiggle the part and that one leg will move in/out of that spot. All the above can happen on IC chips too, so look for one little burnt spot and eyeball the solder joints. Chips are usually more or less just super miniature circuit boards and you can't take them apart, so the best you can do when troubleshooting them is have a schematic of the controller that hopefully says what each pin is supposed to doing. Or a schematic for the chip. Then, with some luck, you can see if it's bad or not. It's very rare people check chips, but I do because I'm too stubborn to change a whole part when just one little thing inside is the issue. Like my truck; people change the kinda expensive power steering pump several times in the trucks life but it's just a little O-ring that needs replacing every 5 or so years.
I had a 300ZX once where the state of the art (at the time) digital dash was known to have all kinds of issues. So I bought one (cheap) with said issues and in the controller there were many badly soldered joints on the IC chips. So I re-did all of them, which was super easy, and it was good to go. Same old story, the joints were soldered too cold and the solder never flowed to the pins so they were barely making contact. I guess good enough to pass QA but after time the teeny little contact connection point gets glitchy. The other thing I learned is I'll never own another Nissan ;) because that was just one of many pita issues and overall the cars design sucked imo. A MB was my next car, which was another cheapie because the owners wife continued to drive it after a radiator hose let go. Rather than pull over, which would be inconvenient, she drove it to gas station and warped the head. For me it was a cheap and easy fix, but I was so impressed how the car was built I was hooked for life. Ok, enough rambling...
So search for info on the net and trace the wires for issues. That power comes from somewhere and imo it comes from the controller.
Wish I could tell you more but I've never had to work on one of those systems so these are generic thoughts on car electronic issues.
Here's one place I'd try; mercedesmedic.com which has lots of info on all kinds of things. Also; youcanic.com/vehicle/mercedes-benz
This one: justanswer.com/mercedes is a pay service where you chat with old salt MB mechs that have probably seen it before and have the answer in their back pocket. I think it's like $30 for a month or something but not really sure exactly how it works. I looked into it last year because I have an issue I can't figure out and I refuse to take it to a dealer or shop, but so far I'm still too stubborn to ask those guys. Common sense says I should just pay them, but my stubborn side is strong with the force ;) I got the link for them from others on misc forums that claimed they were great and solved their issue. So if you do try them let me know how it goes and how much $ it was.
Whatever the case, best of luck and be sure to post the cause and solution for the next guy.
 

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Discussion Starter · #5 ·
My guess is there's one fuse for all of them. I'd say that with 99% confidence but 1% you never know what weird things they do. I'd also assume that the controller is providing all that power and it gets all it's juice from one fuse. Probably through a relay that get it's power from a fuse. So if some are getting power then I'd assume it's not a fuse and the controller is the issue. Or wiring between the controller and inj. So trace wires to the source to look for something causing it. I use either a sharp probe on a multimeter to push thru the wires insulation, or use a pin or needle. That way you can check the actual wire in case the connection on the plug at the end is bad. If that conn is bad you simple take it apart and solder it. Sometimes it's a pain to get them apart and may damage/break it, or even need to cut it apart, but you can just use epoxy to put it back together. Usually you can buy replacement plug connectors for stuff like that. With multiple going bad at once I kinda doubt that's it, but if you were in there working on the filter or whatever it's possible you did something. Often times the inj plugs/wires are sticking up higher than most things in there and people set a parts box, tool bag, tray or whatever on the eng and the weight on the plugs/wires can be the straw for an ancient connection that was nearing failure anyway.

Meanwhile I'd research common failures/issues with that system because odds are the failure has happened to many people and someone has posted about it. And try to find a schematic for the controller. It's a pretty old system but I'd imagine they use transistors to control the injectors because relays aren't fast enough. Hopefully the controller is not epoxied together so you can take a look-c at the guts.
When I open up something electronic like that I first look for any burnt parts which should be obvious. Things like resistors, transistors, capacitors, copper traces on the board etc will be visibly burnt or have a burnt hole on it where the smoke got out. It's a goofy old saying with electronics "Don't let the smoke out", as if the smoke is the spirit of the part and once out it's dead ;)
I also look for any broken solder joints at the legs of those items. I find that is the case on a lot things where one leg to one item was simply not soldered good and over time it finally lost conductivity. Usually you can see it because the solder didn't flow nicely over the parts and freeze, but instead looks more like the leg of the part had non-stick teflon on it and the solder did not flow. Often you can wiggle the part and that one leg will move in/out of that spot. All the above can happen on IC chips too, so look for one little burnt spot and eyeball the solder joints. Chips are usually more or less just super miniature circuit boards and you can't take them apart, so the best you can do when troubleshooting them is have a schematic of the controller that hopefully says what each pin is supposed to doing. Or a schematic for the chip. Then, with some luck, you can see if it's bad or not. It's very rare people check chips, but I do because I'm too stubborn to change a whole part when just one little thing inside is the issue. Like my truck; people change the kinda expensive power steering pump several times in the trucks life but it's just a little O-ring that needs replacing every 5 or so years.
I had a 300ZX once where the state of the art (at the time) digital dash was known to have all kinds of issues. So I bought one (cheap) with said issues and in the controller there were many badly soldered joints on the IC chips. So I re-did all of them, which was super easy, and it was good to go. Same old story, the joints were soldered too cold and the solder never flowed to the pins so they were barely making contact. I guess good enough to pass QA but after time the teeny little contact connection point gets glitchy. The other thing I learned is I'll never own another Nissan ;) because that was just one of many pita issues and overall the cars design sucked imo. A MB was my next car, which was another cheapie because the owners wife continued to drive it after a radiator hose let go. Rather than pull over, which would be inconvenient, she drove it to gas station and warped the head. For me it was a cheap and easy fix, but I was so impressed how the car was built I was hooked for life. Ok, enough rambling...
So search for info on the net and trace the wires for issues. That power comes from somewhere and imo it comes from the controller.
Wish I could tell you more but I've never had to work on one of those systems so these are generic thoughts on car electronic issues.
Here's one place I'd try; mercedesmedic.com which has lots of info on all kinds of things. Also; youcanic.com/vehicle/mercedes-benz
This one: justanswer.com/mercedes is a pay service where you chat with old salt MB mechs that have probably seen it before and have the answer in their back pocket. I think it's like $30 for a month or something but not really sure exactly how it works. I looked into it last year because I have an issue I can't figure out and I refuse to take it to a dealer or shop, but so far I'm still too stubborn to ask those guys. Common sense says I should just pay them, but my stubborn side is strong with the force ;) I got the link for them from others on misc forums that claimed they were great and solved their issue. So if you do try them let me know how it goes and how much $ it was.
Whatever the case, best of luck and be sure to post the cause and solution for the next guy.
My guess is there's one fuse for all of them. I'd say that with 99% confidence but 1% you never know what weird things they do. I'd also assume that the controller is providing all that power and it gets all it's juice from one fuse. Probably through a relay that get it's power from a fuse. So if some are getting power then I'd assume it's not a fuse and the controller is the issue. Or wiring between the controller and inj. So trace wires to the source to look for something causing it. I use either a sharp probe on a multimeter to push thru the wires insulation, or use a pin or needle. That way you can check the actual wire in case the connection on the plug at the end is bad. If that conn is bad you simple take it apart and solder it. Sometimes it's a pain to get them apart and may damage/break it, or even need to cut it apart, but you can just use epoxy to put it back together. Usually you can buy replacement plug connectors for stuff like that. With multiple going bad at once I kinda doubt that's it, but if you were in there working on the filter or whatever it's possible you did something. Often times the inj plugs/wires are sticking up higher than most things in there and people set a parts box, tool bag, tray or whatever on the eng and the weight on the plugs/wires can be the straw for an ancient connection that was nearing failure anyway.

Meanwhile I'd research common failures/issues with that system because odds are the failure has happened to many people and someone has posted about it. And try to find a schematic for the controller. It's a pretty old system but I'd imagine they use transistors to control the injectors because relays aren't fast enough. Hopefully the controller is not epoxied together so you can take a look-c at the guts.
When I open up something electronic like that I first look for any burnt parts which should be obvious. Things like resistors, transistors, capacitors, copper traces on the board etc will be visibly burnt or have a burnt hole on it where the smoke got out. It's a goofy old saying with electronics "Don't let the smoke out", as if the smoke is the spirit of the part and once out it's dead ;)
I also look for any broken solder joints at the legs of those items. I find that is the case on a lot things where one leg to one item was simply not soldered good and over time it finally lost conductivity. Usually you can see it because the solder didn't flow nicely over the parts and freeze, but instead looks more like the leg of the part had non-stick teflon on it and the solder did not flow. Often you can wiggle the part and that one leg will move in/out of that spot. All the above can happen on IC chips too, so look for one little burnt spot and eyeball the solder joints. Chips are usually more or less just super miniature circuit boards and you can't take them apart, so the best you can do when troubleshooting them is have a schematic of the controller that hopefully says what each pin is supposed to doing. Or a schematic for the chip. Then, with some luck, you can see if it's bad or not. It's very rare people check chips, but I do because I'm too stubborn to change a whole part when just one little thing inside is the issue. Like my truck; people change the kinda expensive power steering pump several times in the trucks life but it's just a little O-ring that needs replacing every 5 or so years.
I had a 300ZX once where the state of the art (at the time) digital dash was known to have all kinds of issues. So I bought one (cheap) with said issues and in the controller there were many badly soldered joints on the IC chips. So I re-did all of them, which was super easy, and it was good to go. Same old story, the joints were soldered too cold and the solder never flowed to the pins so they were barely making contact. I guess good enough to pass QA but after time the teeny little contact connection point gets glitchy. The other thing I learned is I'll never own another Nissan ;) because that was just one of many pita issues and overall the cars design sucked imo. A MB was my next car, which was another cheapie because the owners wife continued to drive it after a radiator hose let go. Rather than pull over, which would be inconvenient, she drove it to gas station and warped the head. For me it was a cheap and easy fix, but I was so impressed how the car was built I was hooked for life. Ok, enough rambling...
So search for info on the net and trace the wires for issues. That power comes from somewhere and imo it comes from the controller.
Wish I could tell you more but I've never had to work on one of those systems so these are generic thoughts on car electronic issues.
Here's one place I'd try; mercedesmedic.com which has lots of info on all kinds of things. Also; youcanic.com/vehicle/mercedes-benz
This one: justanswer.com/mercedes is a pay service where you chat with old salt MB mechs that have probably seen it before and have the answer in their back pocket. I think it's like $30 for a month or something but not really sure exactly how it works. I looked into it last year because I have an issue I can't figure out and I refuse to take it to a dealer or shop, but so far I'm still too stubborn to ask those guys. Common sense says I should just pay them, but my stubborn side is strong with the force ;) I got the link for them from others on misc forums that claimed they were great and solved their issue. So if you do try them let me know how it goes and how much $ it was.
Whatever the case, best of luck and be sure to post the cause and solution for the next guy.
 
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