Help starting E3 2500 for first time - carb noob!

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ashnz

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Hey guys

I have recently acquired a 72 2500 here in NZ and am trying to get it started for the first time in atleast 10 years. The car has been sitting idle for 20 odd years and I want to just get it running on its own steam so I can work out what path I take with the restoration.

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I have almost got it going by macguyver-ing it together but I am pretty new to carbs and dizzys so struggling a little to get my head around it!
Motor cranks, has fuel getting to carbs via fuel pump into jerry can, , 135-145 psi compression all round ,has good spark and have sounds bloody close to wanting to go - have had it run for a sec on starter fluid but didnt want to rev at all.

I am pretty confident it is carb related but the below is where I am at with it.

The ignition barrel was mangled and the key wouldnt turn it, so have just bypassed the ignition barrel for now to get it going. I have it set up like this for now - green and yellow plugged into eachother gets the ignition on (lights, dash, etc work) and then I just fire the starter with the red and black. Where is the purple wire meant to go in this equation? I am wondering if that might be stopping the spark when starter switch isnt engaged.

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The next part, and I am more sure this is more than likely the issue - is the carbs.

The linkages between pedal and carb were all pretty tight and gross so just disconnected all the linkages and doing throttle by hand to eliminate that.

I am unfamiliar with these twin carbs and how the vac controls the choke to be honest. Carbs are both getting fuel and can see /smell fuel so no worries there. All of the vac hoses were just ripped off it and I cant see where they would go, someone suggested blocking all of them off for now so have done that as well as the vac advance on dizzy. Photo below shoes what the carbs are like and what the vacuum situation is. I am also not ruling out that the carbs are just totally stuffed from sitting around for so long - to be fair, they feel pretty stiff and gross, I have tried lubricating all the moving bits and that made it a little better but am totally open to the fact that they are just no good.
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Any help or tips would be much appreciated - I am really keen to get it going so I can start pulling it all out and rebuilding it!
Cheers
Ash
 
Have fuel to the carbs - those fuel hoses don't look so great- if you have a tiny split you will have issues.
Have spark at the plugs?
Are your plugs wet after cranking?
Have you cleaned the carbs, or removed them from the manifold?
If car has sat a long time carbs could be clogged up with gunk and old fuel internally.
You'd still get the fuel smell after cranking but no bang..
I'd also be replacing all of those vacuum lines and hose clamps.
Vacuum leaks are not your friend in that game.
 
Yes, replace all the hoses.

My 2800cs would try to start when I bought it, but at best would only run on a few cylinders and then die as soon as the throttle was moved off idle.
I replaced the points with an electronic pickup, a Pertronix, and that allowed the car to start and run, but it was impossible to time as the spark timing was not stable at all. It would even occasionally backfire through the carb. The distributor needed repair or replacement so a rebuilt distributor was purchased off eBay.

But there were other issues, the fuel pump started leaking, so an electric pump was installed instead for now. I took the carbs apart and cleaned them, replacing the gaskets but not the jets as they were checked and found to be clean. One other issue happened then as the gasket between the top and main body of the carb was a little too small and it would hang up the float, keeping it from closing the needle valve and allowing the gas to flood out the vent, through the air cleaner housing and onto the ground. Caught quickly with no fire fortunately.

There are some posts here that discuss the Zenith carbs, the search tool is your friend. I'll post a couple I just grabbed below.
You can find parts diagrams on realoem.com, the prices are old since the site is static, not updated.

I have the BMW service manual for the E9, call the Blue Books because of their covers, if you have questions I could scan some pages for you. The carb info should be virtually identical for the E3 and E9.

1

Thread 'Zenith INAT 35/40 - rebuild w/ some questions'

Greetings!

I am trying to revive my 1966 230S Mercedes-Benz with Zenith 35/40s.

I hoping I can get some help - even though this application is for a Mercedes.

There is very very very little information available from Mercedes sources - luckily I found this fine forum and the technical documents posted. It's been very useful. Basically these carbs are about as simple as Zeniths can be compared to the E9 version. The ONLY electronics are the bi-metallic spring for the choke. There are no sensors/switches or emissions devices like the BMW have. I suspect later model MBs probably have...
Ulrich 3.0 CSA

Thread '3.0 CS: correct mounting of starter lid to carburetor Zenith Inat'

Hello all,
I may have a problem with the correct mounting of one of my starter lid of my 3.0 CS

problem was: one of the starter lid was loose (No 12 in drawing). So I removed it and checked it. The spring was Ok also it is electrical Ok.

I than mounted it again. BMW manual doesn´t say exactly how to mount it. You can put the driving dog arm (Pos17) in different positions while connecting it with the spring.

I tried it in different ways. If car is cold both starter flaps are mooving smooth from closed to maximum opened (if actuated by hand)
But after car was started and cooled down the...
 
Go to main page, tech info for E9 and there will be all you want to know about Zeniths and rebuild.

Pull your fuel sender, check the tank for crap......even though you are working out of a jerry can, that does not mean debris in the tank has not made it to the carbs in the past. I would also pull the thermo start valves ( those sqr silver boxes on the side of each carb). These are basically cold start valves. You can test them in hot water. Ensure at least the static timing is ok. Vacuum leaks are always lurking.

IMO, don't let anyone convince you to swap out to Webers.
 
Thanks for the replies. To be clear, I am going to be pulling the motor out and rebuilding it all - I just want to get it running so I have some sort of idea of what it's doing...plus it will keep my kids happy that the "old rusty bmw" that they have been working on is running!

From the above replies, I think the best way forward is to pull the carbs out and give them a clean (not a full rebuild), reassemble them and replace the vac lines. The posts above have outlined everything I think I need so will see how we go... wouldnt be surprised if they are just blocked and full of 20 years of scum - like the rest of the car.

Thanks alot!
 
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