i have a 1990 f150 with a straight six and the problem is i bought it cheap and it wouldnt run when i got it i put some good gas in it and checked the spark and plugs all seemed too look good and started it ran rough really rough just kept dieing so i started timing it using the old number one spark plug and timing light method and got it timed it ran good until it got warmed up and lost fuel pressure and died and didnt wanna start back up so cycled the pump a few times and checked the fuel pressure gauge and had fuel pressure agian until i started it while warm and just lost pressure any ideas would like to get truck running for summer

 

How long had the truck been sitting before you bought it? If you are for sure losing fuel pressure, I would change the fuel filter.

 

going to get one right now thanks ill let you know the trucks been sitting for a few years gas was terpintine looking and smelling then i syphined it all out and put premium in it just took off fuel filter and looks rusty so should i clean the tank or just a new fuel filter

 

It sounds like you will have to eventually remove the tank to clean it out good.

 

ok new fuel filter and started right up then ran at 50 psi for a few mins then lost pressure and started running rough then turned it off and cycled the pump with the key a few times got back up to 50 psi and started right up then started to loose pressure agian after a few mins of running at 50 psi did it agian and got the same result when it looses pressure it drops down to about 25-30 psi and runs crappy or itll die