Sometimes car won't start without pumping pedal

golf
volkswagen

#1

Couldn’t find Polo on the list. Have a 2003 VW Polo. Had a fuel pump replaced cost $800 and it didn’t solve the problem for long. After this had two mechanic shops run disagnostics on the car and both found no issues. Sometimes I have to pump the pedal and for 5 mins car won’t start and sometimes the car starts normally and drives normally for a few days. It’s up to date with services and the two recent diagnostics picked up nothing. Can anyone recommend a mechanic in Brisbane that doesn’t rely on computer diagnostics to solve this sort of problem?


#2

It’s curious that pumping the pedal seems to help. That used to be the case w/carbs, but electronic fuel injection like your Polo has, shouldn’t have much of an effect. If anything it would indicate perhaps that the fuel/air mixture is too rich for some reason, and by opening the throttle valve by pushing on the pedal, it is allowing more air into the engine, to counter-act too much gas.

hmmm … my guess – and this is just a guess – is that you have a leaking fuel injector. When you stop the engine no fuel is supposed to leak from them. But if it does, it could flood the engine & could cause this symptom for the next start attempt. One way to tell if this is happening is a fuel pressure leak down test. They’ll presurrize the fuel system, turn it off, and monitor the fuel pressure over time to see if it is dropping. Sort of like checking for a leak in a balloon by blowing it up fully, then watching it the next few hours to see if it gets smaller and smaller.

I presume you mean Brisbane Australia. Not much chance of getting a recommendation here for there. But suggest asking friends, relatives, co-workers, fellow bar hoppers and church goers, anybody you have a trusted relationship with, who they use to fix their VW’s. As a last resort you may have to take it to a VW dealer. A proper diagnosis may require equipment only they have. On the upside, this should be eminently fixable.

If you want to try something yourself, bring all the suggested routine engine maintenance up to date. Engine air filter, fuel filter, spark plugs, spark plug wires, etc.


#3

Try turning the key to ON without starting the engine for 3-4 seconds a few times before turning the key to START. Post the results. If it works, it means your fuel line is depressurizing when the car is shut off, and possibly draining back to the fuel tank… which would suggest also a leaky injector.

As George said, in carbureted cars pumping the pedal sprayed fuel into the throttle body to help start the engine, but in electronically fuel injected (EFI) cars it does nothing. Carburetors fed fuel into the engine from a “float bowl”, which was not at all dependent upon the electrical circuits being energized. EFI cars only feed fuel into the engine when the pump is energized and electrically operated (via solenoids) injectors open and allow fuel to be sprayed into the throttle body. They will not respond to the pedal unless the circuits for the fuel pump, the ECU, and the injectors are enabled.

Post the results of my suggestion. If it works, your choices are to have the reason for the fuel drainback repaired or build the suggested protocol into your morning ritual… which I did on an old truck of mine when I began having your symptoms. :slight_smile:


#4

Thanks for the advice I has been about 2 weeks since I reported this problem. most of the time the car turned on ok only when doing that trick of turning it on/off. Then I had the fuel injectors cleaned and the car is running wells so far straight away turns on. Thank you for the advice it really pointed me in the right direction.