fuel pressure issues
Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
fuel pressure issues
I have searched, I see threads but I never see one that says they resolved the issue without taking to stealership. Our c32 was running perfect last night, went to leave this morning and turns over but doesn't start. Frst thing I thought was cps, replaced, still nothing. pulled the cover off the fuel pump, had my wife turn the key to position 2 and nothing. jumper the pump straight to battery and works fine. the relay in the trunk is clicking as well. I can't find a definite solution besides someone replacing everything and still nothing working. Anyone have any real insight on this issue at all please help me out.
Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
Ok fuel sending unit 10.29 volts, across all 4 wires, going to the wiring harness of the fuel pump same voltage. But going out to the 2 fuels pumps is nothing. I can ring continuity thru eCh wire but just no voltage thru the harness. Helppppp
Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
Connection
The one inside the tank is coming from the sending unit. I have voltage going to it. The other 1 on the main fuel pump that goes to the secondary pump doesn't show voltage. Unless I unhook the secondary smaller pump. Both pumps operate just fine hooked to the battery. After charging the battery everything is hitting almost 11 volts.
Junior Member
Joined: Aug 2014
Posts: 67
Likes: 1
2003 C32 AMG
That is very confusing. I went through something similar where one of the pins on the level sending unit had started to melt and would cause intermittent issues (car wouldn't turn over) until I finally found the problem.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
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Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
That is very confusing. I went through something similar where one of the pins on the level sending unit had started to melt and would cause intermittent issues (car wouldn't turn over) until I finally found the problem.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
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Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
been waiting till today for all my parts to come in, everything showed up except the friggin sending unit. it came but since I live in an apartment, they required signature, it was not left. so now I have to wait. which really pisses me off as they delivered sam and fuel pumps to the main office. but didn't leave the unit as they normally do the office signs
Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
so I got the c32 going again. it turns out the rear sam was bad. but I did screw u my fuel level sending units some how. now in my search for used parts, I sent everything back I originally ordered except the rear sam. nothing matched. my c32 has a completely different wiring harness style to what other w203's have. I drove to Dallas to get a pump and rear sending unit out of the same friggin year c32, vin showed it was the same. get there and it is not the same. wtf is up with Mercedes changing the harness out mid year?? blew my mind.
Thread Starter
Member
Joined: Jun 2015
Posts: 118
Likes: 2
From: Houston,tx
c32 amg
ok guys bit of help here. I have our c32 running again. the aftermarket pump i ordered first didnt work as well as the sending units as they had a small square style plug on them let alone didnt have the double double pump system. i knew it was to good to be true. Mine did have the flat 4 plug pin going from the sending unit to the pump itself. so i ordered the nice $1500 dollar set, with sending unit that of course seems to be the same black square 4 wire plug not the flat 4 wire plug. i didnt pay much attention when installing but i did notice that the sending unit fuel level wiring is different on the unit itself compared to what i had originally. of course i tossed in the trash. does anyone happen to have a photo of a sending unit that might have the flat 4 pin harness i can use for reference to rewire this thing??
Last edited by kramykram; May 13, 2017 at 11:56 PM.
Newbie
Joined: Nov 2018
Posts: 3
Likes: 0
C32 AMG
melting connector
That is very confusing. I went through something similar where one of the pins on the level sending unit had started to melt and would cause intermittent issues (car wouldn't turn over) until I finally found the problem.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
From my research at the time, the level sending unit tends to cause electrical issues that a lot of people end up assuming is the pump and replace the whole assembly. A level sending unit is a 1 to 2 hundred bucks from what I remember and you are obviously handy enough to to do the swap so I would suggest starting there. But your voltages across the different points is confusing so I am not 100% positive that is your issue.
