1978 super beetle will not start when warm outside.

[lakes73]

HELP!!...When the outside temp.gets above about 80 my 78 super beetle w/fuel inj.will not start...It will start right up in the cool morning..but if I leave her outside in the sun,she will crank and crank,but no start...I pulled the fuel line off of the cold start valve...no fuel would come out when I cranked the motor...came back later in the eve,when the temp outside was around 60...cranked the engine..fuel came pouring out of the line..I re-connected the fuel line to the cold-start valve and the bug started right up....What should I check first?..Any help for this noob would be great.Thanks in advance.Chris.

[JerryMCarter1]

Might be just the sitting-- I would start with making sure the fuel filters are new.

Then believe it or not - I could be electrical-- so replace the grounds-- battery to body and tranny cold -- no contact on the grounds

From there the next time you must check for fuel and then check for spark

_________________
Experience always triumphs over hearsay and You get to select which theory to believe

[EVfun]

You pulled the fuel line off the the injector, leaving the injector in place? If no fuel comes out of of that line when cranking you are not getting any fuel when cranking, since the injector pressurized fuel lines are all connected. In this event, you are looking at the double relay and more likely the connections to it.

If you pulled the injector and it didn't spay fuel when warm, but did when cold, then it sounds like the thermo-time switch has failed. My thermo-time switch is marked (faintly, in one of the flats of the hex head) 8S 35C. That means it will only spray for up to 8 seconds or until it reaches 95 degrees Fahrenheit. It has a heater inside to make it reach that within 8 seconds. If the thermo-time switch doesn't turn on the cold start valve when the engine is cold (even if it's 70 outside) starting is slow, though mine will cold start if I crank for a while. The manual says it may not start without the cold start valve. If the trigger temperature on the thermo-time switch drifted down enough starting could be a problem, unless it was even colder so the thermo-time switch still turned on the cold start valve.

[Randy in Maine]

Chris,

Check your PMs. I sent you one yesterday.

[lakes73]

Up-date...Car started up fine yesterday morning...later in the afternoon,when the outside temp.got to 85+,the beetle started and I let her idle for 10 min,shut her off....waited for 30 min...tried to re-start..she would just crank and crank..no start...the car has fuel-injection...When I push in and open the lil door inside AFM,she will start and idle fine...Any ideas on what is making the AFM not to work right when the outside temp is hot?...Summer is short here in Michigan and I want to drive her..Any help would be great..Thanks in Advance.Chris in Michigan.

[EVfun]

The AFM may not be the problem. The double relay may not be starting the fuel pump in response to cranking the engine. It should turn on the pump if either the AFM flap is open a little or if the engine is cranking (that connection is through a diode in the double relay.) If the engine is cold enough that the auxiliary air regulator is open the engine may pull enough air to move the AFM vane and turn on the fuel pump. If you set up the case again where the engine won't start try holding the throttle partly open when cranking and see if it fires.

The AFM may have a sticking problem that is made worse by being hot. It wouldn't take much so you would have to very carefully push the flap and feel for slight sticking, then find it, then fix the interference. If you lucky it may be making a visible mark.
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[lakes73]

ok,I will check that out...I got a new double-relay and tried that,still would not start...If I turn the key on..and push in on the lil flapper-door,I can hear the fuel pump running w/o turning the key all the way to try to start the car..I will let you know what I find out when looking at the AFM.Thanks,Chris.

[webdawg]

Mine used to do that also until someone on here told me to NOT pump the throttle, but push it to the floor. Works everytime!
_________________
My first Bug '63 and My current bug' 73

Kingman, Az VW Club http://www.brownsbacker.com/club/

[ColinB]

I'm having the same problem. I convinced myself it was the fuel injection, then the computer. It didn't correct with a squirt of starter fluid, so how can it be the thermo time switch?

[wrocek]

Tons pages to read

http://manuals.type4.org/ljet/index.html
http://x19.xwebforums.org/wiki/images/e/e4/VW_L-Jetronic_Fuel_Injection_Workshop_Manual.pdf
http://www.vw-resource.com/vw-resource.com_non_ssl/fuel_injection.html
http://www.thesamba.com/vw/archives/manuals/afc_fi...Manual.pdf
http://www.thesamba.com/vw/archives/manuals/afc_fi...r_1974.pdf

then ask Fuel Injection Guru here @

http://www.thesamba.com/vw/forum/viewtopic.php?t=21015&postdays=0&postorder=asc&start=0
_________________
159 2001 678, FI convertible.
AJ 133584*
Made Monday, September 18th, 1978 -> 381-9460

[VWCOOL]

some good reading there

[Yehan73]

Ask yourself this question. What are the components working when the car is cold, and now when it's hot? That your answer. CSV does not spray if engine is hot. AAR is mostly closed off. The temp 2 should have a lower ohm rating. My guess is its your temp sensor or your temp sensor #1 next to the crank pully. Test both hot and cold.

[ColinB]

Will do. Ran fine this weekend. Read through the manuals again. What is the best temp to test the temp senders at?

Not the thermotime switch. Starts fine when the switch is at 135 degrees.

Anything else change at high temperatures?

[VWCOOL]

watching this thread with interest - and sympathy.

Can you check for spark when it doesn't start (hot)? Maybe it is NOT the injection?

[ColinB]

Finally happened with the car at home. Out to check all these things before it cools down and the symptoms go away.

[ColinB]

Ok. The potentiometer tests for the intake air sensor are right. The temp2 sensor shows 1000ohms at 100F. Anybody know if this is right? I'll try later when all the way cool. The only value in Bentley is for 68F. Not sure it will get that cool tonight in Gallup.

Dwell and timing are right (when symptomatic) so I don't think it is the timing.

Anyone know a direct test for the temp1 sensor in the intake air sensor?

Any other suggestions?

I wonder if it will start in the AM.

[Government]

Can you check pressure before and after? Fuel pressure that is.

[ColinB]

Fuel pressure is good.

[ColinB]

Found this link:

http://www.ratwell.com/technical/TempSensorII/TempSensorIIGraph.jpg

So my reading of 1000 ohms at 100F is a bit off. Is this far enough to be a problem?

[wrocek]