I have a 1987 f150 with a 4.9 stright 6 engine it first started off wut a alternator problem got that fix then a selenoid problem got it fixed then i was gettin no fuild delivery so i changed the fuel pump inside the tank changed the external pump plus the filter so im gettin fuel all the way through the lines to the bleeder and into the rail. STILL WONT START. i talked to many mechanics and im hearing the crank sensor is gon out but there is none and also im hearing that the timing might be off how cn i solve this problem weather its the timing or not

 

See if U have strong intake suction. If low vacuum that is UR problem.

 

Maybe it could be a bad Camshaft or Crankshaft Position Sensor.

The computer needs to know where to pump fuel & which spark plug will ignite. Most of the time mechanic misdiagnose this problem as bad fuel pump & ignition system.

If can easily check if the camshaft sensor is bad by using a multimeter. Rotate the engine slowly using a breaker bar. You should see a pulsing voltage signal. If you see a steady voltage, replacing it will solve the problem.

 

ok but the only thing is when i try to crank it up it turns over but will not stay crank

 

Voltage problem to it ?

 

No I got a brand new battery

 

U need to have the parts store test UR system. Odds are it is a solenoid or relay problem. A VOM and a few tests will tell U where the voltage drop is if U have one. Remove the starter and take it in if U have no other options.

 

I have high voltage

 

I keep it on a battery charger so I have a good battery

 

Probably not the battery charge that is low. It is the current carrying thru the system starter to ground that is off. Testing the starter is easiest with a vom or parts place. I have a tester that couples over the battery cables to register the amp draw and charging capabilities. It works on either cable & wires. + or - and points out the direction the problem points at. Note, all current must register to the battery in both cables or alternator. Sometimes the - cable is best trouble shooter. I have seen a simple battery cable that changes its ability to conduct electricity by heating up when in starter condition amp flows. It can work one minute and not the next. Finally open is the result. GM type are really bad for it. Simple things like cleaning the ground cable connections where they fasten to the motor block or frame are easy. This eliminates one source of problems usually.