Have a 89 F-150 4.9 6 cyl, Std Trans. Truck had symptoms of a clogged Fuel filter, so I changed and now it is throwing fits. If I get it started, it runs smooth for a few minutes then acts as if it is starving for fuel. I have changed the electric fuel pump on the frame, filter and relay. after it dies it will start but barly run. If i let it sit, it sometimes starts then dies soon. I am also running only the back tank so I changed the port on the rail mounted diverter valve, no change. it once started, ran for 10 minutes at idle, shut if off and 5 minutes later back to the starving symptoms

Help

 

What's your fuel pressure reading?

 

Unfortunatly i do not have a gauge. I do know that after it dies there is nor pressure at all at the schreader valve

 

You still have a fuel pump problem them and the only part left is the intank pump.

 

I puled the line off at the diverter valve and turned over the engine and plenty of fule came out?

 

Clogged diverter valve then? Maybe try bypassing it?

 

I'm having similar problems with my stock '87 4.9, manual trans. It will start right up, but as soon as I put a load on the engine, by either stepping on the gas or going up a hill, it sputters to a stop. I pulled the code...95, fuel pump ground problem. I went thru every ground on the truck, replaced the fuel pump relay, changed the high pressure pump on the rail (had a spare one), and put a new fuel filter on without success. So then I took the plunge and dropped the fuel tank (a one tank truck). I tested the tank's fuel pump and discovered that it would run intermittently which would account for the bad ground code. I put a new pump in the tank and was pretty darn happy until I drove it. The truck still has the same fuel starvation type symptoms. I hooked up a fuel pressure guage to the injection rail, and ran it to the dash so I could see in real time what was happening. Turn the key, +/- 52 lbs of pressure. Starts great and as I put load on the engine, I watched the fuel pressure drop to 20-30 lbs. and unless I bring the engine to an idle right away, the engine will die. If it dies, it starts right up with 52lbs. of pressure. I thought the rail pump was noisy, sounding like it was cavitating. I also put my ear up to the bottom of the tank and could hear my new fuel pump singing in there, but with an occcasional cavitating like sound. I then decided to start working my way back thru the fuel system from the filter, looking for an obstruction. My truck has a water separator type filter on the rail between the tank and the high pressure pump on the rail. I took it out and blew thru it. It was not free flowing. There is a small plastic spring loaded valve on the supply side which seemed to be sticking in the extended/down position, so I pushed it up and out of its channel, to the point where it was basically inoperative. I put it all back together and the truck runs great! Lots of power. Whoa there cowboy, not so fast! I took it in to get it smogged and it failed big time. WTF? I have noticed that the fuel pressure gets up in the 60lb. range when I give it gas. Could this be too much pressure for the injection system, which would then be allowing too much gas into the cylinder with each injection squirt? I thought the pressure regulator would take care of an over pressure problem. Is that little spring loaded valve that important? I hope some of this is helpful to others. I couldn't find any other threads that matched my experiences so here I am!