350SL wont start

[dpatterson]

Hi Folks,

Looking for any useful clues to help with my latest project. Recently acquired a '73 350SL with manual transmission. Has been in storage for past 7 years and needless to say I'm having some grief getting it running. I have replaced the fuel hose at pump (totally disintegrated) and thrown in a new battery (man those 11 plate jobs are expensive). Spark is excellent, fuel delivery seems OK (pump is going fine, removed and cleaned filter in tank before I put any gas in her) and she cranks over beautifully (oil pressure coming up on the gauge just on cranking). Will fire and run for a few seconds if I give it a blast of engine starter down the air cleaner but refuses to continue running or to fire without the engine start spray.
I swapped the EFI computer over with my other car, to no avail.

Starting to run out of ideas on this one. Any further clues would be appreciated.

Cheers,
Daryl

71 250CE
72 350SL auto
73 350SL manual

[cbdo]

Just a guess, and I'm certainly no mechanic, but it seems you're getting a combustible mix to the cylinders only when enriching the combustibility with your starter spray. Between that and the long storage, I'm thinking injectors that need either cleaning or replacement. FWIW--good luck!

[dpatterson]

Thanks Craig,

I suspect you are right (and I'm no mechanic either but at least my father was) - the injectors were my next port of call. Seems to me its got to either be injectors or control of the injectors (ie computer). Will pull them out and get them cleaned and try again.

There is a slight wrinkle in that the car is in Auckland, NZ and I live in Sydney, Australia and therefore I only get to attack it when I'm over there (all too infrequently). Hope to remedy that problem soon by freighting it over, once it has been repainted (half the cost of doing it here!).

Cheers,
Daryl

[kip Foss]

Daryl,
Nice to hear from an Aussie. I lived in Perth from '73 till '77. Nice place-at least it was then. I haven't been back since '85 when they were having the America's cup race.

If Aussie fuel is anything like US fuel the stuff will gum up faster than a rabid roo can run. The gum is nearly impenetrable. I let an outboard engine sit up for a few years and nearly had to dynamite the stuff out of the carb bowls. One drop is enough to clog up a needle valve. I couldn't find anything that would disolve it.

Car buff here in the States that don't use their cars often recommend using aviation petrol. It doesn't have the additives that auto fuel has and you probably won't have to pay road tax on it. Granted it is a bit more expensive, but if you don't use the car as a daily driver it isn't that bad.

[dpatterson]

Thanks Kip,

Yeah I hear Perth is nice but have as yet to make that trip. I suspect you are right about the dried up fuel residue. I have a friend with an ultrasound cleaner for injectors and I'm hoping that will do the trick. I'm convinced that nothing is getting through them at the moment.

As for the Avgas I havnt tried that but have ample access to it as my other pastime is flying. We often "dispose" of 100/130 grade fuel when defueling it from light aircraft when they are overweight. Its illegal to put it back into another aircraft due to contamination risks in handling so it usually ends up as lawn mower fuel. Never occured to me to try it in my Benz.

Anyway I'm back on a plane to NZ in April and am determined to get her running then. I'll post an update.

Cheers,
Daryl

[elau]

You may want to change the fuel filter while you are at it.