If it isn't the gas--What is it?? - PeachParts Mercedes-Benz Forum

MBZ86 · #1 04-02-2009, 03:37 PM

Hello, 1986 420 sel
The car has set idle for about a year and would not start. I discovered that no fuel was getting to the engine. Assuming that fuel could be ransit and possible blockage of tank screen, filter, lines etc, I drained tank , blew out the tank screen the return line from engine to tank.

I replaced both pumps and the filter. I flushed out the incoming fuel line to replace the old gas with new before trying to start it again. Within 4 or 5 cranks, with the help of a little starting fluid, she started up and ran and idled fairly decently.

After warming it up I decided to give it a test drive around the neighborhood. I took it very easy to begin with allowing it to shift through all the gears etc. As I gradually tested it a little harder I found that at about 2500 rpm's it stalls and dies. It will start right back up with ease.

In order to get it over 2000 rpm's I have to drive it in its lowest gear (only b/c of speed limits and stop signs on the street I am driving it on).
In addition, at what ever speed or rpm's, if I rapidly depress the accelerator it will also stall and die.

I believe that everything from the tank to fuel distributor is in good working order. I have not touched the fuel distributor or anything beyond. Could it be that the distributor is gummed up from the old fuel that has been sitting in it for so long? or ?????

What do these symtoms indicate from your experiences?

Thanks for whatever suggestions you can offer!

pawoSD · #2 04-02-2009, 04:00 PM

It might be gummed up....perhaps run a couple cleaning doses (whole bottle in the tank) of Redline SI-1 Fuel system cleaner....its awesome stuff.

MBZ86 · #3 04-02-2009, 04:56 PM

Thanks pawoSD I have been reading about that stuff and I will try it.
My only problem is i'm afraid to take the car out for fear of it quitting on me. I don't feel it is reliable enough to take out on the road. Would it have the same effect if I dumped the redline in and just let it idle or can I put anything in the fuel distributor?

clm · #4 04-02-2009, 06:27 PM

What is gumming up is your fuel distributer.( The eight legged spider in the top of the intake. ) The inner workings are very intricate, precision plungers and gaskets etc. These do not do well when left sitting for long periods of time. The gas disolves and leaves a varnish that gums every thing up. I have seen them lock up completely. It is also vacuun ran, so there is not direct force from the throttle pedal. Take your time- use the cleaner and take it for several trips around the block and get the throttle moving and hopefully you can get it freed up. Good luck!

pawoSD · #5 04-02-2009, 09:35 PM

Perhaps an extra heavy cleaning dose.....like half a tank of premium plus a whole bottle of redline.....then drive it around near home for a while....I bet it will get better and better as the cleaner goes through.

MBZ86 · #6 04-03-2009, 02:20 PM

Hi Guys,
Thank you for your response. Late yesterday afternoon I picked up a bottle of Redline SI-1. I already had about 10 gallons of new gas in it so I poured a half a bottle of it in the tank. I fired up the car, let it warm up a little while and revved it up to 2000 rpm's for about 20 minutes. By the time I was ready to call it a day the car didn't seem to bog down as much as it did when I started it. Probably wishful thinking but I will try it out on the street today with load on the engine.

BTW-If I put the whole bottle in a half tank of gas, would I destroy the engine or make it run worse than it is. If not I will give it a try!!

Thanks again guys!!!

pawoSD · #7 04-03-2009, 04:14 PM

I'm sure its safe to dump the whole bottle in.....I've used over 1 bottle's worth in about 17 gallons with only great results.

I'd say go for it, it sounds like it needs some serious cleaning.

However, its best to add it before fueling, so it can be properly mixed in with the whole tank. So perhaps pour in a bottle then add a few gallons of gas.