1985 380SL - Acceleration problem - stumped

[skyline223]

Hey guys,

Seeking help with my newly acquired 1985 380SL. I have found great help through reading other posts but I feel at my wit's end with this car at the moment, hoping you fine folks may be able to provide some insight. Here's the deal:

85' 380SL. Purchased from a widow, beautiful condition, but has sat for a few years.

The seller had a local mechanic drain the old gas from the tank. This mechanic also replaced the fuel pump and fuel filter.

I purchased the car because it seemingly ran great... in her driveway. On the drive home, it became apparent there was an issue.

The car starts great, idles great, but bogs down with any acceleration whatsoever. If you really go easy on the gas, you can get it up to speed and it will hold 60mph on flat ground no problem..
The day I got it home, here's what I did:

1. New non-resistor plugs gapped to 032
2. New plug wires
3. New fuel filter
4. New air filter
5. Changed oil and filter
6. Pulled fuel tank, cleaned thoroughly, replaced pickup screen
7. Visually traced all vacuum lines, found no clear issues
8. Checked timing and function of advance

At this point I was sure the car would run great, but alas, it ran absolutely no different than before.

Here's where things get slightly interesting. I started to inspect the WUR, and the first thing I did was pull the fuel lines and inspect the micro mesh filters. Well, they were completely gummed up. I removed the filters, cleaned them thoroughly, and reinstalled.

I went out for a test drive after this - THE CAR RAN PERFECT. Tons of power, peppy acceleration. I was ecstatic! Until 3 minutes later. It went right back to it's old ways. Boggy acceleration and lack of power. WHAT?!

I checked the mesh filter in the WUR again, but it was still clean and clear. I started throwing parts at the car in a helpless effort:

1. New remanufactured WUR
2. New O2 Sensor
3. New OVP Relay

But again, none of those new parts made any difference. So here's the condition of the car as of today.


-Starts perfect
-Idles great (economy gauge pegged full left)
-Apply gas, the engine bogs (backfires, economy gauge goes full right)

I have ordered a mityvac and smoke machine to further evaluate the vacuum system. But I keep going back to the fact that the car ran perfect for three minutes after cleaning the WUR filter, then reverted. Confusing.

Other notes:
-New plugs are fouled already
-One time I spotted the catalytic converter glowing red. Seems like the car is running much too rich, but hey - that ole computer is supposed to handle that!

Thanks for bearing with the long post, and I appreciate all the help indeed! I wish she was as hardy as her diesel sisters!

[Frank Reiner]

1) Be certain that the centrifugal advance mechanism in the distributor is free, and that there is increasing advance with increasing RPM. Check the centrifugal advance with all vacuum disconnected from the distributor. Centrifugal advance should total about 34-36 deg. BTC.

2) A very hot catalytic convertor can be caused by retarded timing, however it is more likely caused by a rich mixture.
Disconnect the lambda valve (frequency valve). If it is sticking open, or if the controller is sending an erroneous signal it will create a rich condition.
A WUR that is not heating will also cause a rich condition.

[cuning]

before you buy anything, buy A 98cent bottle of gas line antifreez, (dont laugh) poor in tank and let run in idle so it goes through the system. If that does not cure it, if your filter was fouled, it sounds like a blockage at your gas distributer.

[vwnate1]

When I went through this the problem was the return line (steel pipe) for the F.I. system ~ I borrowed the special F.I. tester tool and my son swore up and down he'd checked it when he didn't (too lazy) so I wasted a lot of time looking elsewhere .

Eventually I decided to begin from the beginning my own damn self and found the problem right away .

Just a thought .

[Tuli]

Sounds like someone put a ping pong ball in your gas tank.
I'm serious