W124 1994 E320 Fuel Pump Question
 

Picked up a 94 E320 a few days ago for a few hundred dollars. 175,000 miles, interior in fantastic condition, leather, Black Pearl Metallic exterior in decent shape, a few clear coat issues, but nothing to bad. No signs of being wrecked, no rust, no dings or dents, etc.

Why was it only $300??

Apparently, from what I was told, was the original owner (family friend of seller) took great care of vehicle but the fuel pump failed which coincided with an illness of the original owner and so the car sat in her garage.....and sat......and sat some more. Until she asked the seller to just get it out of her garage since she no longer was able to drive due to her age and health.

Seller told me the car sat for around 5 years.

Anyway, original plan was to part it out. However, after thinking about it, just seems like a complete waste if it something as simple as fuel pumps to get it running. I know it will need many, many things due to being neglected for so long, but I basically want to see if I can get it running and go from there.

I purchased a cheapo fuel pump and filter off Amazon, drained all the nasty fuel, and removed old pumps and filter. Tested old pumps and they are non functioning. Unfortunately, for some reason, I only ordered 1 pump and this car has the dual pump setup.

My question is this: If I only hook up 1 pump, will the one pump be strong enough for a reliable test to see if the car will run?

I have already installed the one pump and filter, just waiting for battery to charge a little more before I test it out.

Thanks in advance.

-Scott

I think it will work except under high volume demand situations e.g., highway speeds/hard acceleration. Remember that other parts such as the injectors will be gummed. Give it some time with fresh quality premium fuel and quality fuel cleaner.

PM sent.

Just what I wanted to hear. Thank you Sugar Bear. If I can confirm that it will run and it was bad fuel pump, I will replace fuel pumps and filter with Bosch, Mann.

Battery was sufficiently charged, turned ignition on, heard fuel pump turn on, checked for leaks before cranking and saw a steady trickle of gas leaking from the banjo bolt. New cheapo filter and pump didn’t come with new washers so re-used old ones.

Will stop by dealership tomorrow and get new ones. Hopefully then I will be able to fire it up and get a good idea of what I am dealing with.

Put correct crush washers on, put a few gallons fresh gas in tank and fired it up. Took several tries, but finally got it running. One time it actually idled on its own for a few minutes before stalling. All this on one cheapo full pump.

As I was watching it idle, I started thinking about all the issues I am going to run into with a car that has sat this long. While I would love to keep it and bring it back to glory, just don’t have the time, energy, money, etc for a project like this.

So sadly, I have decided to strip it down and part it out. Will begin that process hopefully this weekend.

sfsegui, persevere with this vehicle instead of parting it out. Hopefully, you have some service records so you know how well this vehicle was maintained during the time the elderly woman owned it. Check the condition of the spark plugs, if they are a tan color that means the engine is running properly and not burning oil. Replace the spark plugs with Bosch F8DC4 gapped at .032". Add some Techron to the fuel to clean out the fuel delivery system. Check/replace the air filter. Once you get the engine up to operating temperature, turn it off and drain the oil. Change oil and filter. Inflate the tires to 32psi and drive this vehicle extensively to confirm that it is dependable.

Our 1991 300CE sat in our garage for 2 years, and suffered no ill effects. I had not put gas in it for those 2 years; however, it started easily after charging the battery. These older MB vehicles are very durable with a little TLC.

The CIS FI cars have pumps in series in order to attain high pressures needed for the system to work properly. In this case, one pump might run your car if the pumps internal pressure relief is set above what is required for CIS FI.

If your pumps are in parallel ( I don't think this was ever the case ) then one pump would make the car run.

The 1994 E320 is HFM-SFI, not CIS-E.

I wonder if someone used the CIS dual pump assembly on a HFM car.

My 94 wagon uses 2 fuel pumps

Are they plumbed in series for higher pressure ( like a CIS car ) or parallel for higher volume ?

In series

Why does a system that operates in the 36-44psi range require pumps in series? Series pumps were used with KE-jet, a system that operates in the 84-90 psi range. The second pump of a series configuration is used to boost the operating pressure above that achieved by the first pump.

Fuel pumps
 

In series pumps from mbz book

Fuel pumps
 

In series pumps from mbz book,m3m1,m3m2

I had this failure and the pumps are in series, it runs fine on one pump and no performance limitations. The dual pumps could be to provide reliability but they both tend to fail at the same time as mine did within days of each other. Either pump will reach full pressure with a strong battery. So there is no indication its needed to achieve high enough pressure. Old thread but I had to comment having gone through all the troubleshooting and repairs..95, 124 wagon.