Cold starting problems?

[DCOP]

I have a '70 T w/ 2.2 & webers. It runs great when it's warmed up. But getting it to start when it is cold is a challenge! It take 6 or 7 tries +....turns over, starts then dies...pump it... turns over, starts then dies...takes a lot of finesse with the accelerator to keep it running. Once it finally catches it will stay running after a minute or so. The hand throttle doesn't work, but this doesn't act as a choke anyway..does it? Any suggestions would be greatly appreciated.

[J P Stein]

You are not alone.

The description you gave pretty well matches my experiences.
Only my closest neighbors are aware of this embarassing routine.
The wife has given up commenting on it.

I don't have a solution, but I'm working on it.

[Oldporsche]

The weber IDA 3C's and varients, do not have choke mechanisms. This starting routine sounds a lot like mine.

The idea with the hand choke is to get the idle fast enough to keep it from dying while getting it to warm up. Pulling up on it handle has no choking action at all. I need to hook up mine.

Good luck,
David Duffield

[J P Stein]

This is starting (NPI) to look like a support group.

Webers Anonymous.

[john walker's workshop]

it doesn't have to be that way. the idle jets need to be at least .55, and .60 for larger engines. the original .45 and .50 caused problems like you described. two or three pumps before cranking usually works. if it dies, two more before cranking again. pumping while cranking doesn't work as well.

[wckrause]

Perhaps a conversion to CIS would help? (Ok, this is the one time that I'll make a dig against carbs).

[J P Stein]

If I start it daily, it fires right up. I also don't get a cloud of smoke..
But if I let it sit for a week......yetch. There must be a clue here

Though compression is 175 across the board, the rings that came with the aftermarket pistons don't seem to do a very good job of sealing out oil leakage (sigh). Maybe it will improve with milage. Then again, maybe it will be my own personal bit of hell.

Please forgive an old farts ramblings.

[CraigD]

I have a 71 T with Zenith carbs. I pump 2 or 3 times and pull the hand throttle 1/2 way up prior to attempting to start. Fires up almost instantly then make fine adjustments with hand throttle. About 1/2 the time requires only 1 try others 2 tries does it. I think the hand throttle is very important for this procedure letting in more air and fuel mixture while the engine warms up. I agree with John, you need at least 55 idle jets. I replaced my smaller jets with 55s and it made it much easier to start. I am actually contemplating getting a jet reamer to enlarge the old jets to 60s.

If your carbs are popping when cold and smoothing out when warm this is an indication that the idle mixture is too lean assuming ignition timing, dwell, plug, etc are all adjusted properly/in good condition. Check ignition system first as any changes here will affect the carbs.

Anyone have a reamer they could loan me or that I could send my old jets to for reaming?

[Early_S_Man]

If your idle circuits are OK ... but the carbs haven't been cleaned or rebuilt in many years, the accelerator pump diaphragm may have holes or cracks in it. The output volume of the accelerator pump needs to be measured for all six cylinders!

There is a special calibrated vial -- like a miniature test tube, for measuring the quantity of injected fuel per barrel of the carb. The spec is 0.5 cc per stroke of the pump. You can make a substitute from an insulin syringe by melting the tip where the needle slips on with a soldering iron , and cutting the body to about 2" and wrapping/glueing (with a hot-glue gun) a piece of wire to hold the new 'tool' with. Lower the measuring device below the accelerator pump nozzle, then raise it slightly ... so all of the pump output will be caught.

From my experience ... rebuilt Webers with a new pump diaphragm only need one or two full pumps of the gas pedal to start in any weather. My procedure for starting is ... with the hand throttle all the way down/off, pump the foot throttle one full stroke and release, then hold the throttle partly open while cranking, and when it starts, raise the hand throttle until idle speed is 1500 rpm or so. In extremely cold weather or if the first cranking try didn't work ... use two full pumps of the foot throttle before cranking. Anything more than three pumps ... indicates a problem with the accelerator pump circuit to me, and testing the pump output to see if i in spec is called for.

If pump output is low, blocked passages or cracks in the diaphragm is probable. Then, carb. remova, disassembly,l and cleaning in a vat-type soaking carburetor cleaner is in order. In the following diagram, the pump diaphragm is #45. After removing it, hold it up to a bright light to look for holes or cracks.

[Milu]

What worked for me on two 911s with webers, a 246 Dino and an Alfa Spider was: turn key, wait 30 secs, two pumps of accelerator, 1/4 throttle on accelerator pedal, engage starter. They would all start regardless of how cold, but they were all much happier if they were started at least weekly.

[pjv911]

Milu why would you wait 30 seconds? Are you warming up the points ? I dont understand what that will do for it.

[Milu]

In the case of the 246 it was reccommended because of the Dinoplex electronic ignition, (it only had points as a back-up system), which needed the time to work properly, I don't know why, but it was the recognised procedure for a known problem. On the other cars it might have been psychological on my part or a feature of old wiring and connections, I just know it worked. It was also worthwhile to hold the clutch pedal down when cold starting. Less effort for the starter? Oh yes, don't forget to hold left ear with right hand and chant "please start" while turning key for added protection against gremlins!

[T Bird]

My procedure for a cold start (50 degrees or less) is to turn the key and listen to the fuel pump. When the float bowls are filled, I can hear fuel being dumped back into the tank by the return line. If the car is cold and has not been driven in several weeks (usually the case), this may take 5-10 seconds. Waiting for the float bowls to fill ensures that the accelerator pumps are going to deliver the prescribed amounts. Next, I pump three times and crank. While cranking, I crack the throttle plates open with slight pressure on the gas pedal. The engine fires immediately and runs fine until the fuel delivered by the accelerator pumps is used up, which may take 5-10 seconds. If it's cold enough outside, the engine will die. If so, I repeat the process with two pumps and this usually does the trick. If it's not so cold, the car will run fine at the first attempt, so long as it is held at a fast idle of 2000 RPM. After a minute or so, I can lower the idle to 1500 RPM.

The Porsche workshop manual indicates that .8cc +/- .2cc is the prescribed quantity of fuel that must be discharged at each nozzle. I have had very good results with .75cc. PMO recommends .6cc to .8cc.

Good luck.