Hard to start when hot?

[Bluedc]

Hi,

I have a 69 Ghia (1600 twin port) which starts perfectly when cold
even when it hasn't been started for a few weeks. However it doesn't
start very well when I the engine is hot. If I am on a long motorway
drive and stop for 10-20 minutes the engine needs to turn over a lot
on the starter motor before it will start. If I stop and start
straight away it will start without any problem. If I stop for an hour
it starts again without any problem.

This has been a problem since I bought the car 3 years a go. Since
then I have had a partial engine rebuild, new fuel filter, new fuel
pump and rebuilt the carb.

The VW garage that rebuilt the engine checked the timing and carb
adjustment. They suggested that the problem may be the petrol
evaporating in the fuel pump but couldn't explain why the evaporation
may be happening or how it happened. The insulation block is in place
under the fuel pump. The oil temperature gauge is reading 220°F
(105°C) when doing about 60mph for an hour or two on the motorway on a
hot (by British standards) day. My VW garage checked the engine over
and suggest that the sensor may not be accurate as there is no reason
for it to be that hot.

Any thoughts would be very appreciated.

Thanks

Will

[P.J.Berg]

Does it have a stock size oilpump? Check valve clearance.

J.

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[Bluedc]

I have an external oil filter with the in and out through the oil pump
and the valve clearances were set by the garage when they did a
partial rebuild earlier this year. The problem was there before this
work as well as now.

Thanks

Will

[Speedy Jim]

I offer 2 possibilities:

1) Failure of Ignition switch contact after long running time.
Easy test: Watch the OIL/GEN lights whilst cranking.
Both should be ON, though the OIL light might go out after
some interval of cranking.

But if *both* go out during cranking, then the switch is failing.
Note that the Starter section of the switch may continue to operate
normally.

2) More likely, I think: Engine bay heat after a long motorway drive
"soaks" into the fuel pump and the carb bowl, raising the petrol temps.
When it reaches a critical point (well below the boiling point of
water), the fuel will begin to boil. In the pump, this will raise
pressure in the outlet pipe to very high levels in a short time.
The pressure may get high enough to overpower the float needle valve,
flooding the carb.

Fuel in the bowl will also boil. Yes! You can actually hear it do so.
And, if you look down the throat, you can see great white clouds of
vapour. There may also be a stream of fuel siphoning out the
brass vent tube. And the accel jet nozzle may begin dribbling raw fuel.

All this raw fuel dumped into the manifold will make the engine very
hard to start.

Later engines (about 1971) had a fuel pump with a pressure relief
built in as VW began to recognize the problem. But the carb situation
remains to this day a baffling problem. I think it is more severe
today due to reformulation of the fuels, but I can't prove that.

There is no one easy fix. You can install an insulating spacer under
the carb. Or block off the manifold heat. Add washers to the float
needle valve to lower the float level. Prop open the deck lid
slightly to increase cooling. No guarantees that any/all of these
will solve the problem.

Speedy Jim
http://www.nls.net/mp/volks/

[Speedy Jim]

Speedy Jim wrote:
> Bluedc wrote:
>> Hi,
>>
>> I have a 69 Ghia (1600 twin port) which starts perfectly when cold
>> even when it hasn't been started for a few weeks. However it doesn't
>> start very well when I the engine is hot. If I am on a long motorway
>> drive and stop for 10-20 minutes the engine needs to turn over a lot
>> on the starter motor before it will start. If I stop and start
>> straight away it will start without any problem. If I stop for an hour
>> it starts again without any problem.
>>

<SNIP>

>
> I offer 2 possibilities:
>

Edit: There could be other ignition-related failures,
such as the Coil failing as it gets very hot. Ditto
for the condensor.

To test for this kind of thing would require checking
spark at the HT lead during the time that the engine
refuses to fire.

Jim

[Jan Andersson]

If the engine overheats, it will become harder to start. Yours does seem
to be running on the hot side, but oil temperature is not the only thing
to look at. You can super-cool the oil and make the gauge happy, but the
heads may still be cooking.

Time to look at all the cooling system components, including engine tin
and engine bay seals, thermostat, flaps, fan blades, belt tightness...

[Jan Andersson]

Don't lower the float level. It makes the engine run leaner, throughout
the range and may cause further overheating and even engine damage.
If the float needle valve leaks and causes flooding, it will continue
doing so no matter where your float level is set at.

Since it starts right away after a longer wait, your carb bowl most
likely never got empty due to boiling and evaporation. Fuel would have
to mysteriously re-appear within an hour, without running the fuel pump,
for that to be possible :)

So maybe it flooded. You'd need to investigate this while it's hot and
not starting well. Check the valve lash too. If you have stock aluminum
pushrods, they make the valve clearances get SMALLER as the engine warms
up. If the valves were adjusted too tight when cold, they may never
close fully when hot.

[dave AKA vwdoc1]

Do you hold the gas pedal to the floor when trying to start that hot engine?
I vote that it is flooded after it sits for a few minutes!

"Bluedc" <wi...@bluedc.co.uk> wrote in message
news:d1c237fd-a3f1-4771...@o6g2000yqj.googlegroups.com...

[John]

Same in my Type 3. Eventually worked out when engine cold floor the
accelerator to set chokes and it starts dead easy but when at working temps
I dont touch the accelerator.
I put it down to just an endearing idiosynchracy!.
John

[Bluedc]

Hi, thanks for all your responses - I'll check through everything
suggested.

I have tried different ways to re start from hot as when I first got
the car and found the problem - I thought I may be flooding it by too
much accelerator. Now I turn it over quite a bit before putting my
foot down. Although as suggested above It does feels to me like trying
to start a flooded engine. And this sound like it could be caused by
too much heat. I will re check all the cooling system and get a carb
spacer.

Thanks for you help.

Will

[Joey Tribiani]

"Bluedc" <wi...@bluedc.co.uk> wrote in message
news:d1c237fd-a3f1-4771...@o6g2000yqj.googlegroups.com...

>Any thoughts would be very appreciated.

>Thanks

>Will

doesn't sound like you are overheating(at least not excessively), and a bit
of carb flooding is "normal" with these engines... do as VW suggested in the
manual when starting a warm engine, hold the accellerator pedal to the
floor(no pumping) then turn the key..

[Jim Ed]

A long time ago during Summer, our old car stalled at an
intersection.
A country boy stopped and helped us.
He said it had a vapour lock.
He walked across the street and bought a cold bottle of pop from a
Coke machine.
Then he slowly poured the cold soda pop onto the intake manifold right
below the carburetor.
The old car started.

Any cold liquid would work.

If no cool liquid is readily available and you are alone out in the
boonies, you could open the deck lid and take a whiz on the fuel pump
to cool it off.

Note : this is also a good last resort remedy for a heat injury.

I have a 1973 VW Beetle with a stock T-1 1600cc DP engine.

I tried the following tips.

Check fuel pump pressure.

For my model, it should be between 3 and 5 p.s.I.

I used the small hole gaskets on the heat riser.

They are kind of hard to find.
I got mine from http://www.aircooled.net.

This is supposed to help keep the heat riser on the intake manifold
from getting too hot.

I wrapped the fuel hoses coming out from the fuel pump with aluminum
foil to help dissipate the heat from the fuel.

Then I covered the foil wrapped hoses with wire loom to help hold it
in place.

But yesterday, I got the engine up to operating temperature and then
shut it off.

After a few minutes I tried to start it.

It was hard to start.

I put the gas pedal to the floor and held it there while cranking the
engine.

It started but I had to use the gas pedal as a foot exerciser to get
the engine running smooth.

This link might help:

http://www.vw-resource.com/vapor_lock.html

<<<<<<<<<<<<<<<<<<<<<<---------------------->>>>>>>>>>>>>>>>>

[Michael Cecil]

On Sat, 29 Aug 2009 07:21:59 -0700 (PDT), Jim Ed <Jim...@msn.com> wrote:

>
> A long time ago during Summer, our old car stalled at an
>intersection.
>A country boy stopped and helped us.
>He said it had a vapour lock.
>He walked across the street and bought a cold bottle of pop from a
>Coke machine.
>Then he slowly poured the cold soda pop onto the intake manifold right
>below the carburetor.
> The old car started.
>
> Any cold liquid would work.

I remember back when I first bought my '70 bug I had a problem with vapor
lock in the fuel line. The metal part of the line inside the engine
compartment rested on the manifold. I used a bit of wire to suspend it
from the fan shroud and never had that problem again.
--
Michael Cecil
http://home.roadrunner.com/~macecil/
1970 VW Beetle "Millennium Sparrow"

[J...@sr.com]

More than likely it is simply purculation of the fuel. The engine temps
transfer to the carb when it sits for a few minutes. There is no air
flowing through the carb to cool it. So the fuel boils and floods the jets
and thus cylinders.
You can usuually add another gasket (as thick as possible) under the carb
and this will help. Also when restarting hot keep the throttle open fully
for a second or two, this will help clear the wet fuel out.