Car starts when fuel pumps have runned but dies after a few seconds and then not start at all..

[johan h]

Hi,

Some time ago I was testing to start the car. the fuel pumps (both?) then buzzed and the car started a few seconds, then it died. After that it was impossible to start. It jumped on for a few seconds when I cut off the power, probably due to the pumps then had built up a certain pressure again. I managed to give it some additional gas on the pedal and then it started and worked really well, after that it was impossible to start again. This must show that it cannot be problems with the immobilizer.

Today I changed the fuel filter (not done since at least 2013). After that, the car started and went really well. I tested to turn it off and on without any problems. However, later, when i took it down from the jack stand ( I believe this was the cause), the problems came back again, as if the slope itself helped to supply the engine with petrol. I tried to replicate this again but the car refused to start, back on square one again...

What i have done so far:
I opened the caps and rotors and it was a slight moisture, i cleaned them and sandpapered the surfaces slightly: no difference at all.
Changed fuel filter: the car startet perfectrly and was running for approx 40-45 min without any problems, then it came back.
I oppened the fuelfiller in order to let go of vacuum.

It feels like this problem is from a lack of fuel and that the engines somehow starve..

What do you guys and girls think?

 

[gsxr]

When you turn the key on (engine not running), the fuel pumps should run for 2 seconds and then turn off. It should do this every time you cycle the key. If not, try a different LH module. The pumps will remain on when the engine is running, but I forget if they turn on when the engine is cranking.

For a test, you can connect a fuel pressure gauge to the rail when the engine will not start and see if there is full pressure. If not, temporarily bypass the fuel pump relay (FPR) with a piece of wire and see if that cures the problem - if so, the LH module is the likely fault. If bypassing the FPR doesn't do anything, the problem is elsewhere.

 

[johan h]

Thank you so much Dave, now the pumps always runs the first time i try to start the car, the second attempt they are silent. If i disconnect and connect the battery, they are sounding again (once). Can this be a sign of bad LH module you think? I have a spare module but do we know any that could repair these boxes?

 

[sheward]

Don't forget the fuel pump relay under the back seat. This relay was intermittently bad on my car and produced similar symptoms.

 

[johan h]

Thank you all, I forgot to mention that i tested three different fuel pump relays before. I changed my LH module now for a spare one and now the pumps are running every time i turn the key. The car started as well. It did not however run on all cylinders but that is another thing to look into. I will change caps and rotors, cables and spark plug and then we will see if the car is delivering as it should, anyway, one step further to a working car!