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10 Posts
Hello, I’m new around here, not a mechanic but I like to take care of issues myself if I can. I grew up overseas next to some mechanic neighbors, had a very tech handy uncle and an aerospace engineer as a father in-law which all have inspired me to look at a problem first before bringing it to someone to get it fixed. I’m writing this in a way so that maybe it will be helpful to someone like me no pro mechanic person. All pro’s, don’t make fun of me😂🙄 if you read it all.
So a few weeks ago, I went to the UPS store, when I came out my car wouldn’t start. Never had a sign before, it cranked fine but didn’t turn over, sounded like I was out of gas. Anyways, I was parked a little uphill so I let the car roll back and after a few minutes it started up again. Driving was fine afterwards, I figured that it might be the fuel pump. Hey, nowadays you type into google “MB cranks but doesn’t start” and there is a storm of Information😱. It did lead me to a faulty fuel pump on its way out, which made sense since it said that it will work again once it cooled off for a bit, but only for so long before it will give up on you.
A couple of days later it happened again, at home as I wanted to put my car in the garage. It was still warm and didn’t start. I waited until the next morning and it started right up again. Meanwhile I read some info on this board that it can be the CPS and not the fuel pump.
So I bought the MB part $45 and installed it, it took me about an hour. Little hard to reach but with a little fiddle and patience it worked.
So far so good, only for a little more then over a week, gas station, I went in came out after two minutes, car didn’t start. I was like, scheisse now I’m stranded. I noticed I was on a little slope and let the car roll down to a parking area, getting ready to make some phone calls. Tried again A little after and it fired back up, with no issues driving home. It sprinted up to 120 with no problem but I knew that I had a problem coming soon.
Two days later I went to the store and it didn’t start again, had someone give me a ride home and came back to it a few hours later, no success. I gave it a rest over night and the next morning, no success. So there was the problem and I remembered one more thing, the relay. Picked it up at the independent mb mechanic in town and had hopes, nothing. Talking to the owner mechanic, he said it’s the fuel pump and that the CPS probably was fine too which I replaced shortly before. He said thats how the fuel pump acts before it dies, it will fire up after it cools down, but only for a few times.
During all that time I kept reading about all this online, watched videos and sometimes a sending unit Was mentioned. I didn’t really understand if it was part of a fuel pump assembly, if the pump alone will cost less or if it’s a part which can be broken and it isn’t the fuel pump at all.
So I called the actual MB dealership to find out about pump and sending unit. $308 before taxes and the sending unit is $326. wow, it’s not just a small fix, that’s going to cost me some $.
I also talked to the independent MB place again and they made me an offer to get it all fixed for $1150!. Meanwhile, I had my car already towed to my home and I had opened up the tank lid to see which plug my fuel pump has and to find a part number. I looked on the www to find a pump and was still confused about the sending unit. After thinking about all other scenarios, it could be electrical and not the pump at all etc., maybe I should just let it get diagnosed before I spend any money on something what is not defect, it wasn’t easy and for me, 1150 is a lot at the moment. So I went back out to the car, turned the ignition and was listening one more time. I could hear something but it wasn’t the pump. So I called the MB garage again and was going to finally order the fuel pump. He explained to me that the tank is like a saddle creating two parts of the tank. In the driver side one is the sending unit to pump gas to feed the tank where the actual fuel pump is located. Now I understood and he recommended saying that my model should have replaced both pumps at the same time since they communicate each other. I already gave him my card number but in the last moment I asked him to order the actual fuel pump only, I can get the sending unit later if it doesn’t work, it only takes a day or two to get it in. Besides that, the side with the main pump was full of gas so I figured that the sending unit must be working.
Got the part the next morning, had my battery already disconnected since I already had looked at the pump before, reopened the lid, disconnected the three hoses and the plug on the top of the pump, lifted it out, let it drip dry, put the new one in, connected everything back in place, made sure the float was free from hoses and cables, put the lid back on, connected the battery again and what a happy moment, it started right away with no issues.
Went out on a little test drive and all worked great. My only fear was that what if the sending unit doesn’t work, then the fuel pump will run dry and I’ll be stranded again. I filled up the tank to see if there are any leaks coming from the tank lid and the sending unit and fuel pump seem to be new buddies. I almost finished the first tank of gas after the repair and There are no issues yet.
I’m happy that I was able to fix a problem for $360, instead of spending $1150 on two pumps and hours of labor.
Good luck and stay safe
So a few weeks ago, I went to the UPS store, when I came out my car wouldn’t start. Never had a sign before, it cranked fine but didn’t turn over, sounded like I was out of gas. Anyways, I was parked a little uphill so I let the car roll back and after a few minutes it started up again. Driving was fine afterwards, I figured that it might be the fuel pump. Hey, nowadays you type into google “MB cranks but doesn’t start” and there is a storm of Information😱. It did lead me to a faulty fuel pump on its way out, which made sense since it said that it will work again once it cooled off for a bit, but only for so long before it will give up on you.
A couple of days later it happened again, at home as I wanted to put my car in the garage. It was still warm and didn’t start. I waited until the next morning and it started right up again. Meanwhile I read some info on this board that it can be the CPS and not the fuel pump.
So I bought the MB part $45 and installed it, it took me about an hour. Little hard to reach but with a little fiddle and patience it worked.
So far so good, only for a little more then over a week, gas station, I went in came out after two minutes, car didn’t start. I was like, scheisse now I’m stranded. I noticed I was on a little slope and let the car roll down to a parking area, getting ready to make some phone calls. Tried again A little after and it fired back up, with no issues driving home. It sprinted up to 120 with no problem but I knew that I had a problem coming soon.
Two days later I went to the store and it didn’t start again, had someone give me a ride home and came back to it a few hours later, no success. I gave it a rest over night and the next morning, no success. So there was the problem and I remembered one more thing, the relay. Picked it up at the independent mb mechanic in town and had hopes, nothing. Talking to the owner mechanic, he said it’s the fuel pump and that the CPS probably was fine too which I replaced shortly before. He said thats how the fuel pump acts before it dies, it will fire up after it cools down, but only for a few times.
During all that time I kept reading about all this online, watched videos and sometimes a sending unit Was mentioned. I didn’t really understand if it was part of a fuel pump assembly, if the pump alone will cost less or if it’s a part which can be broken and it isn’t the fuel pump at all.
So I called the actual MB dealership to find out about pump and sending unit. $308 before taxes and the sending unit is $326. wow, it’s not just a small fix, that’s going to cost me some $.
I also talked to the independent MB place again and they made me an offer to get it all fixed for $1150!. Meanwhile, I had my car already towed to my home and I had opened up the tank lid to see which plug my fuel pump has and to find a part number. I looked on the www to find a pump and was still confused about the sending unit. After thinking about all other scenarios, it could be electrical and not the pump at all etc., maybe I should just let it get diagnosed before I spend any money on something what is not defect, it wasn’t easy and for me, 1150 is a lot at the moment. So I went back out to the car, turned the ignition and was listening one more time. I could hear something but it wasn’t the pump. So I called the MB garage again and was going to finally order the fuel pump. He explained to me that the tank is like a saddle creating two parts of the tank. In the driver side one is the sending unit to pump gas to feed the tank where the actual fuel pump is located. Now I understood and he recommended saying that my model should have replaced both pumps at the same time since they communicate each other. I already gave him my card number but in the last moment I asked him to order the actual fuel pump only, I can get the sending unit later if it doesn’t work, it only takes a day or two to get it in. Besides that, the side with the main pump was full of gas so I figured that the sending unit must be working.
Got the part the next morning, had my battery already disconnected since I already had looked at the pump before, reopened the lid, disconnected the three hoses and the plug on the top of the pump, lifted it out, let it drip dry, put the new one in, connected everything back in place, made sure the float was free from hoses and cables, put the lid back on, connected the battery again and what a happy moment, it started right away with no issues.
Went out on a little test drive and all worked great. My only fear was that what if the sending unit doesn’t work, then the fuel pump will run dry and I’ll be stranded again. I filled up the tank to see if there are any leaks coming from the tank lid and the sending unit and fuel pump seem to be new buddies. I almost finished the first tank of gas after the repair and There are no issues yet.
I’m happy that I was able to fix a problem for $360, instead of spending $1150 on two pumps and hours of labor.
Good luck and stay safe
