Hard Start 1972 A.B 1.3 Twinport

[Marl1993ey]

Absolutley Bamboozled! my car has had an issue starting since i bought it. intially i thought it was an issue hot starting, but it seems i can go for a drive and intially it fires striaght up, if i switch it off and start it back up it fires up fine.

if i leave it a few mins and restart it really struggles to catch, will turn over but not fire up. ive replaced most things in the engine, had various people working on the car (again issue seems to be when left) and never been able to rectify the issue, but it seems fuel related, even though the car runs very well when running.

fuel pump, carb, battery, dist, coil, plugs, leads, starter, airfiler, solid fuel line (over manifold) valves all done.

Would anybody kindly share ideas as im baffled!

Thanks in advance

[sctbrd]

If you run any modern gas with additives it can vapor off at relatively low temps, and the engine compartment is hot after shutdown, with no cooling air.
Problem is the heat causes any additives/ethanol to vapor off in the lines creating gas areas that arent easy to pump. This can be as low as 120F. Also carb gas will vapor off easier causing the bowl to lower level.
Any gas that is from winter blend months would have more of these additives, so if you have leftover gas from last year or spring, it might not help.
Best choice is to use premium gas with no ethanol- 90 or 91 octane, might be labeled as REC-90.

Im fighting the same problem in my 65 Type 34, with gas from before spring.
My next try is to drain my tank fully and fill with only 95 premium (here in Europe it's 100 RON).

I just tried yesterday retarding my timing a hair to see what that does- read here it can help with hot starts. Seems to be cranking easier, so fuel pump will fill lines faster, but I didnt get it on the road to warm it up yet.

Keep us posted.

[Marl1993ey]

Thank you for your message, I didn’t realise that. I do put E5 in the beetle which is super unleaded. Would a 12v fuel pump from the fuel tank feeding to the rear of the engine work better I wonder. Not reliant on the mechanical push rod fuel pump?

[viiking]

Most people in some cold countries do not realise that there are summer and winter fuels. The greater the difference between the summer and winter temperatures, the more likely you will have fuel that is designated as winter v summer.

Winter fuels have more lower boiling point (light) fractions in it to help with cold temperature starts. Summer fuel is the converse i.e. higher boiling point (heavy) fractions to help with hot weather starts.

During the fractionation/distillation step, gasoline/petrol can be removed from the equipment at different levels and so affect what boiling point the fuel is. These can be further blended to achieve what is known as the Reid Vapour Pressure (RVP).

So if you have fuel in the tank from the winter and now it is boiling hot, you will have more problem starting because those lighter fractions will be boiling off. Similarly if you have summer fuel in the car and now it is very cold, those heavier fractions will not be boiling off as easily and again you end up with the same problems.

So if you last filled up when it was cold and now it's hot you might consider to drain and refill your tank.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3

[jinx758]

Choke maladjusted

Too much timing

Dwell not correct

Gas tank not venting

Fuel line/hose near heat source

Possible other stuffs, too but these are simple to check & correct.

Good luck ... stay safe

jinx
_________________
" It's not valuable unless you learn something from an experience. " Henry Ford

It's not unlike the same difference ...

My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor

[VW_Jimbo]

What does your spark look like when tested cold, WOT? Does the choke function? How did you determine that? Gas is new? Last tune up was? Picture of that engine available?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[ashman40]

Next time you drive the car and leave it sitting hot and expect it will struggle to start....

1) Before you make your attempt, walk to the engine and remove the air cleaner so you can look down the carb throat. Give the throttle arm a quick pull and confirm the accelerator pump discharge nozzle instantly squirts fuel down into the intake. This confirms there is fuel in the bowl and now in the intake.
2) Reinstall the air filter.
3) Sit in the driver's seat.
4) Crank the engine without touching the accelerator pedal. You are trying to start the engine with the bit of fuel you squirted down the carb. Does the engine catch?
5) If after a couple tries, press and hold the accelerator pedal down to the floor. Do not pump it. Hold it there. With the pedal held to the floor you are in flood clear mode and are trying to blow out excess fuel in the engine.
6) Crank the engine. Crank for 10-sec at a time, resting 10-sec between attempts. Keep the pedal on the floor. After 3 or 4 attempts you should have cleared any excess fuel from the intake and the engine should start.

Did squirting fuel down the carb before starting make a difference? If so, your problem is a lack of fuel.
Did holding the accelerator pedal to the floor make a difference? If so, you had a flooded engine.
Understanding what was causing your hard start now points you in a direction to investigating WHY there was too little or too much fuel in the engine.

FYI, squirting fuel down the intake before starting is the normal way to start an ACVW engine. Read the second paragraph below.

_________________
AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[sctbrd]

Yes an electric pump up front would get fuel to the pump faster, its a common "fix" for this condition.

I cant find it, but there is an owner's manual that actually says that if youre trying to start a car at operating temperature and the above methods dont work, wait about 20 minutes for it to cool down. Might be a Beetle manual, not sure.

Heat soak on lower pressure gasoline lines was a known thing even with older type gasoline.

[ashman40]

On the points of summer heat causing fuel in the lines to vaporize… I’m sure this is possible (maybe even likely) and would play havoc on a fuel injected car which depends on fuel from the pump reaching the injectors. But engines with carbs run off the fuel in the carb fuel bowl. The bowl acts like a reservoir. Unless all the fuel in the bowl is evaporating or leaking out while the car sits, there should be enough there to get the engine running even if only for a few seconds. This is then enough time for the fuel pump to refill the bowl so the engine continues to run. Even when the bowl is empty there should be enough fuel in the accelerator pump passages to get a squit or two of fuel so the engine will run momentarily.

The OP is reporting nothing from the engine while cranking. This is why i have suggested trying to determine if the engine is either starved for fuel or is flooded. I can see the heat causing the fuel to percolate and flood the bowl and intake once parked and allowed to sit. This can be confirmed by removing the carb top and checking the fuel level on a hot engine before starting it. If the level in the bowl is too high it means the carb inlet valve + float are not controlling the level properly. It shouold he easy enough to clear a flooded state by holding the pedal to the floor while cranking.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[lboos]

Go to page 36 of your owners manual for a 1972 bug, read the
right bottom note: starting the engine at operating temperature, before operating the starter, depress the accelerator pedal fully, DO NOT RELEASE IT, now start.
You might try depressing the accelerator 1/2 way down and hold it there 1st.