A simple job becomes an ordeal
Now that the Long Way Euround road trip is well and truly over, it’s time to delve into the issues I was having with warm starts and stalling on the long downhill sections around Cooma. The issue almost certainly points to a faulty fuel accumulator and fuel pump relay.
What’s an accumulator?
The accumulator’s job is to maintain system pressure after the engine has been switched off. Without this, the fuel in the lines vaporises while the engine is off and can’t properly ignite when trying to restart a warm engine. Cranking the engine for a while forces the fuel pump to push fresh fuel into the lines until it can eventually start. This is in line with the hard warm start issues I have been experiencing, but doesn’t really account for the stalling and so I’m choosing to replace the whole fuel pump assembly components to be on the safe side. I’ll also pull out the fuel tank strainer and check for debris that may have been blocking the lines, though I don’t think this is likely as I have previously had the tank drained.
All of the other fuel system components have been reconditioned over the last 2 years – and I do mean everything:
- Fuel injectors (replaced)
- Fuel distributor (09/2023)
- Warm up regulator (can’t find the date, but sure it’s been done)
- Air-Idle control valve (03/2022)
Almost immediately after I returned home, I ordered the following parts to get right into it:
| Part | Mercedes-Benz Part Number | Brand Purchased | Manufacturer Part Number | |
|---|---|---|---|---|
| Fuel Pump Relay | A0015453405 | Gebe | 993871 |  |
| Fuel Pump | A0020919701 | Bosch | 0-580-464-125 |  |
| Fuel Filter | A0024774401 | Bosch | 0-986-AF8-093 |  |
| Fuel Accumulator | A0004760421 | Bosch | 0-438-170-017 |  |
With the exception of the Fuel Pump Relay, I was able to purchase everything from Pelican Parts in the US and due to the parts being quite small, express shipping was only a few dollars more. It’s pretty impressive that I can order parts from the US and have them here in 3 days, when it can take a week or more to get parts from interstate.
With the Fuel Pump Relay, Pelican gave me 2 options – Genuine for $185USD or URO for $70USD. I didn’t really like either of these options. URO parts are of questionable quality and genuine is ludicrously expensive. I manage to find a 3rd option under the Gebe brand. The Gebe brand is actually manufactured in Germany and costs even less than the URO option so I consider it a good choice. The only problem was that the only company I found that stocks it in the US doesn’t ship to Australia. Fortunately they have an eBay store that does! Shipping is a little slow at 7-14 days, but I was willing to wait.
The Parts came just in time for the weekend, and although I was feeling somewhat run down with a cold, I was keen to get this job done.
I crimped the smaller fuel line with a vice grip and used some quick grip clamps for the larger fuel lines and proceeded to pull everything out. I decided that since I was changing the whole lot out, I would try to pull it all out together rather than piece by piece. This would allow me to reassemble the new parts as a unit on a bench and install it into the car.
Unfortunately, I didn’t clamp of the large fuel lines adequately and had fuel leaking out at a significant rate! I had petrol leaking all over the place and was frankly, not prepared for it. I had a drip try in place in anticipation of a little leaking out, but I did not expect it in the volume is was coming out. So I quickly re-attached the hose to stop the leak. It was at this point I decided, the right thing to do is to drain the tank completely. I had thought of this, but not quite figure out at which point I would do it.
I went looking for my jerry can to collect the fuel into and found a significant amount of gunk in the bottom of it. I wasn’t really prepared to risk getting that gunk back in my fuel tank, so decided to buy a new 20L jerry can. On the way back from the trip, I made a conscious decision to not refill the tank to the top, so the 20L was just about the right size – especially after losing a fair amount to my garage floor! This was made worse since I forgot to remove the fuel cap, so it would look like it had drained when all it was doing was drawing some air into the tank to displace the drained fuel then come gushing out again a few seconds later!
With the tank drained and the floor mopped, I was now able to pull out the pump/filter/accumulator unit without having fuel leaking everywhere around me. I took it over to my bench to start swapping the new components in, starting with the accumulator since it was at the top of the unit. The first thing I noticed was my new accumulator was significantly larger than the old one – odd! Perhaps this was why I was having warm start issues over the last couple of years. It wasn’t significant, but after parking the hot engine for 90 minutes or so, it would take 2 goes to start up as opposed to starting on pretty much the first crank any other time.
I try to screw the new accumulator into the hard fuel line, and it’s refusing to go in. I didn’t notice it at first, but the thread on the new accumulator was a little larger than my old one! There was no way it was going in! What had started as a simple job has now turned into an ordeal due to previous owner mishaps!
I stepped back and did some online research – did I order the wrong part? No! Is the accumulator on the US model different to the rest of the world given the US 380 is significantly detuned? No! What’s going on. It looks as though at some point in my car’s past someone has swapped out these parts to those from a different model. Why? I have no idea. A friend has told me it looks like the accumulator he used on his 300SE. Why would they change it to the 6 cylinder version?
This put the brakes on the entire job, as I needed to find the right parts. It turns out that the hard fuel line is no longer available new, so I will try a wrecker to replace it in the coming days.
While I was under the car I also noticed that one of the fuel lines had started to deteriorate quite badly. So I will order replacements for all of the fuel lines in that area while I’m at it. These are the part numbers I have ordered:
| Part | Mercedes-Benz Part Number | Brand Purchased | Manufacturer Part Number | |
|---|---|---|---|---|
| Fuel line with metal fittings – Fuel Filter to Feed Line | A1234702075 | Cohline |  | |
| Fuel line – Fuel Line to Damper Cage | A1264701675 | Cohline |  | |
| Fuel Hose 5.5x10mm (Outside Cloth Braided) | A1074763726 | Cohline | 2122-0400 |  |
| Fuel Hose 14×21.5mm (smooth rubber) | A1234763026 | CRP |  |
The rest of this job will now be put on hold until I get the new parts for a few days or possibly weeks due to other commitments. It will most likely mean I’ll miss out on Sydney German Autofest too since the car won’t be running – although I will probably show up as a spectator.
