K-Jet fuel pressure test part 4

I’ve been trying to narrow down poor running on my 79 280SE when cold. Previously, I had two issues I was trying to narrow down, high control pressure when cold, and after a while both system and control pressure dropping and fluctuating. I had replaced the fuel pump, which made no difference to the fluctuation issue. I had also sent off my warm up regulator to be cleaned.

When my warm up regulator returned, I refitted it to the car. Even without running the engine, the control pressure was much better. Actually it was now too low. I still had […]

K-Jet fuel pressure test part 3

This is part three of a series where I am trying to diagnose poor cold starts on my 1979 280SE. Please click here for part 1 and here for part 2. In the last part, the fuel pressure tests had pointed to high control pressure. This would most likely be cause by the Warm Up Regulator (WUR). However, after a while the pump became very noisy, and since rebuilt WURs are expensive, I wanted to rule out a bad pump.

Luckily I had a 420SEL parts car on hand. The previous owner told me the fuel pumps were almost new. […]

K-Jet fuel pressure test part 2

Earlier in the week I attempted to run a fuel pressure test on my 1979 280SE. On further examination, I was pretty sure I had it connected up wrong. The instructions call for the pressure gauge to be attached to the larger fitting on the warm up regulator. The warm up regulator is hidden down to the side of the engine on the M110. The bigger fitting is actually a banjo bolt on this WUR, so this time I hooked it up (hopefully) correctly. My goal was to test cold control pressure.

The readings made more sense this time. System […]

K-Jet fuel pressure test part 1

I’ve been trying to get to the bottom of the running issues on my 1979 280SE. The last thing I tried was draining all the fuel and replacing the fuel filter and tank strainer. Once the car warmed up, it actually ran reasonably well. I took it for a drive for about 40 kilometers and it was running better and better. After this drive, I assumed that the running issues was due to bad fuel and that I had solved this part of the problem.

However, when I needed to start the car and move it out of the way […]

new W116 fuel hose, strainer and filter

I recently purchased a W116 280SE. On arrival, it wasn’t running too well, and the symptoms pointed to the car not getting enough fuel. A few weeks ago, I drained all the fuel in the tank and checked the main fuel filter and strainer. After doing all this, the fuel filter and strainer were all that bad. They certainly didn’t look bad enough to make the car run the way it did.

I figured I would be doing a fuel volume and pressure test next. Before I got to that though, it seemed to make sense to install a new […]

W116 fuel filter and fuel strainer

My recently purchased 280SE is not running well. The symptoms feel like it is not getting enough fuel. Strangely enough, performance picked up with more petrol in the tank. Based on that, I wanted to eliminate two fairly obvious things before I started troubleshooting the fuel injection system. Namely, I wanted to make sure the various fuel filters installed on the car were not plugged up, and that I eliminated bad fuel. Mercedes-Benz vehicles of this era are fitted with three fuel filters. There is a fine mesh fuel strainer in the bottom of the petrol tank, next there is […]

Troubleshooting 280SE running issues

One of the things I noticed right away when I got my new 280SE was that it wasn’t running well. It was very hard to start and keep running. Eventually, if I warmed it up a bit it would idle, but giving it much throttle would have it stutter and die. I was able to get it off the tow truck and into the warehouse, but not easily.

Getting it to run properly is my first priority as it will also confirm that the drivetrain is good. My first attempt was to check the spark plugs. I thought that perhaps […]

Evaluating my 1979 280SE

I took the risky move of buying my 1979 280SE sight unseen. This isn’t something I particularly recommend, but you can get a good sense of a car by looking at detailed photos very carefully. The thing that attracted me to this car was the condition of the body and interior. I assumed a couple of mechanical issues in my buy price. I figure you can always sell a car with a great interior and paintwork. This is especially the case with a W116, as the model is known as rust prone, a trait it shares with the 107 and […]

My 1979 280SE project and my quest for the perfect W116

I’ve been thinking about selling my 1986 300SE for a few months and replacing it with something different. I bought that car five years ago when I needed to be able to drive it every day to drop my daughter off at daycare then to the park and ride to get to work. I no longer work in the office every day, so the need to have a full registered car for this purpose is gone.

Last year I dropped it back to club rego. While it got used a lot, it was always second preference to the 560SEL and […]