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Hi All,
I have this weird phenomena recently. When I start my car in the morning while cold outside, it starts right away really good in a touch, but after the car was setting in the sun all day after work and it’s hot, the car has trouble starting!
I can hear the fuel pump working when turning the switch on.
It takes it 2-3 and sometimes more tries to start. I also noticed that when giving it a little throttle while starting (when hot) it helps a bit.
What could be the problem? is it not getting enough fuel or air when hot?
Could it be a bad Air pressure / Air temperature / Throttle Reheating sensor?
It is a 1997 Peugeot 106 GTI 16V. Here’s a detail of the intake / throttle:
Thanks
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Do you have any DTC codes?
It would be best to test this under the conditions. I.E. On a hot day when it doesn’t want to start to check to see if it getting spark and the proper amount of fuel….
Since the engine is still technically cold (not at operating temps) and the only thing that should be warmer is the ambient air temperature. Technically the car still should start as it was when it is a “cold” morning. I.E. in open loop, so your sensors should not play a part in keeping this from starting (but this car is European, so all bets are off I suppose)….. I would check for a fuel delivery issue (possibly fuel filter, possibly the pump itself) or a relay that is going bad. May be interesting to see what the LTFT is when you start it in the morning and what it is when you get get home at the end of the day….
-Karl
I don’t have any codes / don’t have an OBD reader.
I had a feeling it’s a fuel delivery issue since when it does it, at least when it started doing it, it would start if I pushed the gas paddle a bit, but why is it happening only when hot? How does the heat affect if any the fuel filter/pump/RELAY? (if it is the problem).
I was also thinking maybe when the ambient temp is cold, it tells the computer to deliver more fuel so that’s why it starts better? and when hot maybe it’s not getting enough? what should I check?
This is the car:
For the hell of it, try giving the throttle body a good cleaning around and behind the throttle plate..
[quote=”ChrisR1987″ post=67216]Im a little rusty on my knowledge in this field but could this be a sign of vapor lock?[/quote]
Back in the days before fuel injection I would have thought of that.. but that was really hot days on vehicles that were prone to it… I remember wrapping fuel lines in aluminum foil to stop that… 😆
-Karl
[quote=”wysetech” post=67187]For the hell of it, try giving the throttle body a good cleaning around and behind the throttle plate..[/quote]
The throttle body is very clean actually. I’ve just done a head gasket on the car last month and cleaned everything along with new seals / gaskets all around (intake / exhaust / valves..).
The main relay is a double relay for the fuel and ignition and it looks sealed:
It’s pretty expensive too. How do I know for sure if it is bad?
[quote=”ToyotaKarl” post=67256][quote=”ChrisR1987″ post=67216]Im a little rusty on my knowledge in this field but could this be a sign of vapor lock?[/quote]
Back in the days before fuel injection I would have thought of that.. but that was really hot days on vehicles that were prone to it… I remember wrapping fuel lines in aluminum foil to stop that… 😆
-Karl[/quote]
Thats what I thought I just couldnt remember if fuel injected enginess were prone to it too.
[quote=”ChrisR1987″ post=67278][quote=”ToyotaKarl” post=67256][quote=”ChrisR1987″ post=67216]Im a little rusty on my knowledge in this field but could this be a sign of vapor lock?[/quote]
Back in the days before fuel injection I would have thought of that.. but that was really hot days on vehicles that were prone to it… I remember wrapping fuel lines in aluminum foil to stop that… 😆
-Karl[/quote]
Thats what I thought I just couldnt remember if fuel injected enginess were prone to it too.[/quote]
Could it be the problem? can vapor lock happen in fuel injected engines?
Vapor lock is highly, highly, highly unlikely….
What you need to do is be able to read the data that the car is sending you. HF sells a relatively affordable scanner that can tell you what is going on that the computer sees.
If you do not want to purchase such a thing then you are best left taking it to a pro to see what is going on…
I.E. if you think the intake air temperature sensor is not reading the temperature properly, a scanner can tell you what the computer is actually seeing.
Intermittent problems are the hardest to diagnose… The tech must see it when it is happening be able to see what the computer is being told about the situation.
Until you really know, you can parts-mechanic the situation until you may or may not get resolution…..
This is a difficult one because the problem could be caused by:
Fuel pump
Fuel pump relay
Fuel pressure regulator
clogged fuel filter
a bad sensor
bad gas
Dirty fuel injector
Stuck fuel injector
leaking fuel injector
Fuel injector harness problem
Spark plugs
coil packs
ECU
ETC, ETC….Karl
Ive read that it can but its very rare because of the design of the fuel delivery system. The reason vapor lock occurs on carb motors is the system relies on negative fuel pressure and the pump itself is located right by the engine if the fuel heats up and turns to vapor the pump can no longer deliver fuel to keep the engine cool. Fuel injected engines on the other hand use positive pressure and the pump itself is located inside of the fuel tank so its cooler. The only reason an FI engine should develop vapor lock is if the fuel lines reach a temperature that causes to the fuel to vaporize before it hits the injectors. While its not impossible it is rare. The only modern FI engines I know of that can still develop vapor lock is smaller aircraft engines such as those found on single and small twin engine prop aircraft and the reason for that is because of the altitudes and pressures they operate in
Did you have this problem BEFORE you changed the head gasket?
Maybe retrace your steps to see something left disturbed, disconnected etc.With all the info you’ve given I’ll take a stab and say have you tested the crank sensor? I found them to fail on many brands with heat related symptoms. Just a thought.
My first thought is a loose boot or vacuum line that opens up enough to cause problems when the rubber expands from ambient air temperature increase.
Ya know-the more I think about it-the more I’m leaning towards it being an evaporative emission system problem. I don’t know if your car even has one but if it does it could cause your condition. Does it matter how much fuel is in the tank when this occurs? Have you gone back over what you might have disturbed during the head gasket replacement? :stick:
I’ve gone over everything and it seems ok.
I haven’t thought of the fuel amount in the tank, I will pay attention to that and see. Now that you’re mentioning it, I do recall the tank was below 1/4 when that happened the worst.
What I did notice though that after the car was running for a while and stopped / hot, starting is not a problem.
In my car, it has the return gas fumes line going into a carbon canister inside the front right wing.
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