Cranks But No Start ... But Runs When Started

[walterbenedikte]

I guess the problem I am having is fuel pump related ... checked all the basics, but do not hear the pump run when I turn the key to ON. I can crank, the engine will NOT start; if I use starter spray, it will start and run just fine.

There is some circuit that controls the fuel pump status when "key on engine off" - and it should be relevant for me because obviously the pump does not run in this status - but it runs when the engine is running (key on engine on), and will not stop running.

SO I cannot start the engine normally, I can start the engine with starter spray easily, and it will run. When warm, just need to turn the engine off, and AGAIN it will not start (without starter spray).

Found many similar threads but nothing that applies to this specific situation ...

Can somebody help?

Thanks !

 

[wmburns]

Here's a crank with no start check list to get started.

1996+ Crank with no start check list
http://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838

However I don't believe that the fuel pump isn't running at all. Likely that you just can't hear it from the other car noises. Sometimes it is necessary to get very close to the gas tank to hear it. A buddy to help turn the key would help.

BUT........ all this is ASSUMING this is a 1999-2004 model year Mustang.

Further, if this is a model year with a Schrader valve, this offers a way to check fuel pressure.

Regardless of the model year it would be handy to know the voltage reading at the trunk mounted IFS switch. Test with the key on using a KNOWN good ground. For the 1999-2004 model year this should be battery voltage.

For the 1996-1998 model year a reading lower than battery voltage may still be OK.

Also, don't discount the possibility this could be MAF/vacuum leak related.

 

[walterbenedikte]

Thank you very much for the reply ! Thought I would get a message is case of a reply but did not, just noticed your friendly advice ...

By now I have extracted the fuel pump and it does not work (direct connect to 12 V no function); have heard that it is not possible that the engine could run without fuel pump, so it might have given its last spins, because when I started the engine with starter spray, as said, it kept running. But, trying to move the car, it had something like 15 - 20 hp, as soon as it went uphill, just a bit, the engine stopped. But it did idle ...

Now I am waiting for a new fuel pump and hope it was the only defect ...

Thanks, again !

 

[walterbenedikte]

Installed the new fuel pump assembly today; first time key on it ran about 2 seconds ... filled 2 gallons of fuel, again key on, 2 seconds, cranked for just a moment and the engine started immediately and actually sounded more 'energetic' than lately before what now I know was a pump failure. Guess the pump slowly died ... can not wait to take her out ...

Thanks for the help !