help my car randomly doesent start, please i need this fixed!!

[dsmoverboosted]

Well sometimes my car wont start for a while and I am having a hard time figuring out whats wrong because it doesent always happen. Usually first thing in the morning and when i get off work my car wont want to start. I will go to fire it up and it will fire for a sec then die and it can take me 1-10 more trys before i get it started again. If I hit the gas while trying to start it, it gets worse, it violently fires up and dies right away with black smoke pouring out the back then it takes even longer to get it going. Once i fire it up it idles fine (a little low at first but my fiav and isc are blocked off so i think thats normal) and drives great with no loss of power at all but it does pop and crackle when i let off the gas to shift or something which i think might be a part of the problem.

My mpi relay clicks on and the pump turns on (brand new walbro so i can hear it) and i got a brand new fuel filter so there should be plenty of fuel at the rail and since it drives fine without knocking at full boost id say theres nothing stuck in the fuel line. I havent checked the injectors yet but if it was the injectors would it not be a constant problem? I think my fpr is fine, i don't think i smell gas in the vac line (I might smell a bit but it is so faint i am not sure if it is gas or just the smell of an old vac line)

As for spark i have 2 coil packs that i have both tried and 2 power transistors with no change and i got brand new 7es gapped to .28 with new wires too.

I had a bad ecu before that flooded my car with gas and i swapped in a new one from a 93 fwd 5 speed turbo i think it was (i will double check the ecu number but when i bought it i checked the ecu # and vfaq sayed it was capatible). I also checked the caps before i bought it and they where fine but right after i swapped the ecu this issue started happening so i don't know if it is the ecu or just a coinsidence.

sometimes it wont happen for 3 days straight (the hard starting, it will still pop and crackle when letting off the gas) and i'll think maybe its ok but then it will start happening again.

I am sorry about the novel but i wanted to give as much detail as possible. What could cause such a random problem like this? What should i maybe check first?

Thanks in advance Axe

 

[diablos991]

Did you put some lube on the O-ring that is on the Walbro when you installed it?
If that O-ring got torn up or kinked while installing it, it can cause the car to have a hard time starting after it has sat for a while.

 

[bmwisthekey]

another thing you could check is your coolant temp sensor when the sensor and/or wiring to it is faulty, it can cause no starts etc.. just a thought, if u have a logger see what its showing for the coolant temp. is the CEL light coming on?, there is also procedure in manuals how to check this sensor. during starting the sensor tells the ecu how much fuel to inject into the mix so if there is a problem with it or the wiring to it, it may act weird

 

[herblove]

Check your ECU. Make sure your cap have not leaked

 

[dsmoverboosted]

I acually did not lube the o-ring (i know dumb) but this was happning before i installed the pump.

well i have not noticed anything wierd about my coolent readings. The readings i get on the logger start at the outside temp and then normally rise to about 210f. It's not just when the car is cold too just most the time. Sometimes it will happen after a long drive and i try to fire it up right after i shut the car off.

As I stated in my first post i just replaced my ecu with a 93 fwd turbo 5 speed ecu because mine had leaky caps. When I bought the new one I opened it up to check the caps and they where fine.

 

[95talon_in_ma]

I know it's slim, but it almost sounds like vapor lock with the fuel system. Maybe keep the fuel cap off for a few days to see if it still happens or not....

 

[bmwisthekey]

i had similar starting issues, sometimes after i drove the car and shut it off a few mins later i go to start it back up and it would just crank over and over no start, let it cool off awhile and bam would start right up. my prob turned out to be the coolant temp sensor, would do that most of the time when engine was warm, also wouldnt start on cold engine either just made it act really weird

 

[dsmoverboosted]

I know it's slim, but it almost sounds like vapor lock with the fuel system. Maybe keep the fuel cap off for a few days to see if it still happens or not....

what do you mean keep the cap off? Just unscrew it when the car is sitting?

 

[dsmoverboosted]

??