300SD Sudden Loss of Power

BNZ PWR · 02-26-2008, 01:57 AM

Hey everyone I am a proud owner of a baby blue 300SD. It has about 206K and has been largely running strong since i purchased it with 125K a few years ago. Unfortunately, I have been having some trouble that I really want your help with.

When I am merging onto the freeway, (or driving up a slight hill), i get a sudden loss of power when i shift from 3rd to 4th. This only happens when I have less than 3/8ths of a tank of fuel. As a result, I NEVER drive it with less than 1/4 tank. This also SLIGHTLY happens when i have a half or 3/4 tank of gas. I thought it may be the fuel pump, but my mechanic who is very good told me if this is the case, the entire fuel system needs to be replaced. My mechanic does not live near a freeway and it is almost impossible to replicate on surface streets, so i look crazy when i go over there. Otherwise, the turbo boosts strong and the transmission shifts well.

It feels as if the fuel cuts off. RPMS drop dramatically and i can step on the accelerator several times and eventually the power is restored. At first it was merely and inconvenience but it is becoming a very serious safety issue.

Any suggestions or advice would be appreciated!

tanktube67 · 02-26-2008, 02:15 PM

when was the last time the fuel filter was replaced?

ohlord · 02-27-2008, 05:38 PM

your EGR valve?and the tube.Or as above new fuel filter lately.

ohlord

spicyguy2005 · 03-02-2008, 08:31 PM

I have 1989 420sel that has 230,000 miles on it and just last week had the same kind of problem, sudden loss power on highway. Before this happened, the car stop running several times when I am leaving highway and at stop signs. After waiting 10-15 minutes, I could forced the car to start again. I was told that one of the fuel pumps was bad and was replaced with a used one. After that fuel pump relay, fuel filter, and ignition control units (all used ones) were replaced. The car was OK for a couple weeks. Suddenly last week on the highway, I felt like there is no gas coming to the system after pressing on the accelator but it came back in about 10 seconds. After a while it happened again, so I have to go back and get another car. Is it possible to be the same kind of problem? I talked to my mechanic he said that if the problem doesn't happen when he has the car he most likely couldn't tell what is wrong with it.

240D 3.0T · 03-03-2008, 07:48 AM

No, your car is g@soline, this is Diesel.

cur.bill · 03-11-2008, 11:42 PM

Try replacing your hose's s this is exactly what happened to my 300sd last weekend. The hoses were crumbling. I still am getting crud from hose;s by the fuel tank. The primary was getting plugged within 100 miles.luckly I carry spare filters in the trunk. I replaced the 2 hoses by the filter and was able to drive home the 250 miles.

02-26-2008, 01:57 AM	#1
BNZ PWR Newbie Join Date: Jan 2005 Posts: 13	300SD Sudden Loss of Power Hey everyone I am a proud owner of a baby blue 300SD. It has about 206K and has been largely running strong since i purchased it with 125K a few years ago. Unfortunately, I have been having some trouble that I really want your help with. When I am merging onto the freeway, (or driving up a slight hill), i get a sudden loss of power when i shift from 3rd to 4th. This only happens when I have less than 3/8ths of a tank of fuel. As a result, I NEVER drive it with less than 1/4 tank. This also SLIGHTLY happens when i have a half or 3/4 tank of gas. I thought it may be the fuel pump, but my mechanic who is very good told me if this is the case, the entire fuel system needs to be replaced. My mechanic does not live near a freeway and it is almost impossible to replicate on surface streets, so i look crazy when i go over there. Otherwise, the turbo boosts strong and the transmission shifts well. It feels as if the fuel cuts off. RPMS drop dramatically and i can step on the accelerator several times and eventually the power is restored. At first it was merely and inconvenience but it is becoming a very serious safety issue. Any suggestions or advice would be appreciated!

02-26-2008, 02:15 PM	#2
tanktube67 MBWorld Fanatic! Join Date: Nov 2007 Location: California Posts: 2,073	when was the last time the fuel filter was replaced? __________________ 05 BMW 545i (sold) 04 G35 Coupe/lots of Mods (sold)

03-11-2008, 11:42 PM	#6
cur.bill Newbie Join Date: Mar 2008 Posts: 3	Loss of power Try replacing your hose's s this is exactly what happened to my 300sd last weekend. The hoses were crumbling. I still am getting crud from hose;s by the fuel tank. The primary was getting plugged within 100 miles.luckly I carry spare filters in the trunk. I replaced the 2 hoses by the filter and was able to drive home the 250 miles.

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03-02-2008, 08:31 PM	#4
spicyguy2005 Newbie Join Date: Jan 2008 Posts: 11	I have 1989 420sel that has 230,000 miles on it and just last week had the same kind of problem, sudden loss power on highway. Before this happened, the car stop running several times when I am leaving highway and at stop signs. After waiting 10-15 minutes, I could forced the car to start again. I was told that one of the fuel pumps was bad and was replaced with a used one. After that fuel pump relay, fuel filter, and ignition control units (all used ones) were replaced. The car was OK for a couple weeks. Suddenly last week on the highway, I felt like there is no gas coming to the system after pressing on the accelator but it came back in about 10 seconds. After a while it happened again, so I have to go back and get another car. Is it possible to be the same kind of problem? I talked to my mechanic he said that if the problem doesn't happen when he has the car he most likely couldn't tell what is wrong with it.

03-03-2008, 07:48 AM	#5
240D 3.0T Banned Join Date: Apr 2006 Location: Federal Heights, CO Posts: 507	No, your car is g@soline, this is Diesel.