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 Hot Start 602cc 
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Firing on two.

Joined: March 26th, 2010, 8:41 pm
Posts: 214
Post Hot Start 602cc
I have a 602cc A06/635 engine with a 34 PICS carb in the AZU Van.
Cold start with choke - All OK.
Warm start with throttle open - OK.
Really hot start on a hot day- Bit of a bugger. It may take 20 seconds of cranking and then needs coaxing with the throttle and starter even when it first starts to fire.

Once running, good runner hot or cold.

Any ideas to improve Hot Starting ?
BobH


July 30th, 2017, 8:44 pm
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Firing on two.
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Joined: July 10th, 2010, 12:35 pm
Posts: 751
Post Re: Hot Start 602cc
Your induction coil is bad.

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July 30th, 2017, 9:08 pm
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Joined: November 8th, 2009, 5:42 pm
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Location: NL
Post Re: Hot Start 602cc
Official way as by the Citroen manual... Put the accelerator pedal to the floor and leave it there. Then start your engine.. Don,t pump when the engine is hot. Just floor it till the engine comes alive.

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July 31st, 2017, 5:36 pm
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Joined: August 31st, 2016, 12:12 pm
Posts: 290
Location: Hawkins County, TN. USA
Post Re: Hot Start 602cc
bobh wrote:
I have a 602cc A06/635 engine with a 34 PICS carb in the AZU Van.
Cold start with choke - All OK.
Warm start with throttle open - OK.
Really hot start on a hot day- Bit of a bugger. It may take 20 seconds of cranking and then needs coaxing with the throttle and starter even when it first starts to fire.

Once running, good runner hot or cold.

Any ideas to improve Hot Starting ?
BobH


Same here. Usually the worst above 29C/85F. At 97F/36C in the middle of summer, it's even worse.

It was suggested using a resin filled coil. I have one from a Harley Davidson, I just haven't installed it yet. I'm not going to doubt anybody since I've only owned this car for one year but the thing is, every car I own that has a carburetor has the exact same problem. Also the type of fuel pump has no effect.

Trabant 601 (gravity feed)
Yugo (electric fuel pump)
68 Ford Fairlane (mechanical fuel pump)
Citroen 2CV (mechanical fuel pump)

Everyone of them has hot starting issues in the summer. The Citroen seems the worst. 15 seconds of cranking then when it does start , floor it!

I thought I was stranded one day. I had just bought the car and was out tooling around when I stopped at the Bric a Brac store. It was around 35C and could not get it started. I almost ran the battery down.

I think what's going on with these cars is heat rises up from the engine through the intake manifold and causes the fuel to boil and evaporate out of the fuel bowel. So the excessive cranking that is required is from where there is no fuel in the fuel bowel. That's my theory.

Some people have confused this with vapor lock. One time my 68 Ford did vapor locked between the tank and fuel pump.

I installed a blower fan on my Yugo which blows air directly at the carburetor and installed a 185F fan switch in the intake manifold. The fan will kick on and off for about 30 minutes. It seems to help.

http://s222.photobucket.com/user/turbof ... t=6&page=1

Will give the HD coil a shot one day.

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August 3rd, 2017, 5:45 am
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Firing on two.

Joined: March 26th, 2010, 8:41 pm
Posts: 214
Post Re: Hot Start 602cc
Changed the coil for a different 2nd hand one - just as bad. Next time it fails, I have a propane torch with me and squirt propane down the carb (Works well on the lawn mower), and see if it makes a difference. In the meantime, I am going to check valve clearances and ignition timing, points gap. Anything that could change when hot?


August 3rd, 2017, 9:10 am
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Joined: August 31st, 2016, 12:12 pm
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Location: Hawkins County, TN. USA
Post Re: Hot Start 602cc
bobh wrote:
Changed the coil for a different 2nd hand one - just as bad. Next time it fails, I have a propane torch with me and squirt propane down the carb (Works well on the lawn mower), and see if it makes a difference. In the meantime, I am going to check valve clearances and ignition timing, points gap. Anything that could change when hot?


I wondered the same thing. About mounting one of those small 1 lb propane canisters with an a solenoid to a push button or connecting it to the wire going to the starter solenoid so it would pump some propane into the air cleaner to help get the car started. Mounting a propane canister in the engine compartment might be a bad idea.

Another idea I've thought about was mounting a small tank (~.5 liters) in the engine compartment with the fuel line from the tank going in the top and out the bottom before going to the carburetor.

Then mounting a windshield washer pump off the line from the bottom of the tank before it goes into the carburetor . So it would squirt some fuel into the intake manifold rather than having to crank the engine over to allow the fuel bowel to refuel.

I guess another solution would be to mount a separate windshield washer tank and just fill it with petrol and activate it with a push button.

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August 3rd, 2017, 11:37 am
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Post Re: Hot Start 602cc
This Morning, wings off and checked compression. 82Psi and 75Psi cold. Checked tappets and all gaps far too small. Checked torque on head studs - OK. Adjusted tappets to Inlet 0.25mm Ex 0.3mm. Checked compression 138Psi and 112Psi - What a difference. All measurements made with throttle open. I will be off for a run this afternoon and its about 30 deg C, so am hopeful that I have found the problem. I will update later with the results.


August 3rd, 2017, 11:58 am
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Firing on two.

Joined: March 26th, 2010, 8:41 pm
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Post Re: Hot Start 602cc
Oh - Ps: I squirted butane gas around all carb / manifold joints and there wasn't any difference in engine speed, so I deduced there were no leaks. Squirted it up the air intake and engine revs rose, so gas works.


August 3rd, 2017, 12:01 pm
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Firing on two.

Joined: March 26th, 2010, 8:41 pm
Posts: 214
Post Re: Hot Start 602cc
Bummer - that didn't make any real difference. So after a nice hot run (its 32 deg C again today), I swapped the "hot" coil for the original coil which was "cold" and away we went. So I now swapped it back to the "hot" coil, and away we went proving that either the "hot" temperature is very critical, or that there is a different problem. So in short, nothing conclusive to report.
I think that tomorrow I may try a "Butane Start" when hot.


August 3rd, 2017, 4:57 pm
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Joined: March 21st, 2013, 12:04 am
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Location: Exeter, Devon
Post Re: Hot Start 602cc
Not sure I've read the whole topic, but how is the capacitor?
Could you have 2 dodgy coils?
Sorry, just a quick thought whilst I'm cooking tea. :)

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August 3rd, 2017, 5:15 pm
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