Have a 95 f150 5.0, sometimes will not start unless you jumper starter relay.Key turns ok I think it might be the ignition switch. Am I right? Thanks.

 

the relay on the fender? it could be the relay. in fact its most likely the relay. you can get them for like 12 bucks at napa. 10 bucks at oreilly autoparts. but you could check it by having someone turn the ignition switch while you check the voltage to the coil side of the relay. if you have voltage to it then its the relay.

 

i have a 92 f150 with the 4.9l in it. i have to cycle the key to get it to start decently. if i dont it spins for bout 7 seconds. i checked the fuel pressure. the guage reads 0 psi with switch on. and running it reads 46 psi. what would be my problem? im thinkin check valve

 

When you first turn the key from off to on (not to "start") you should hear the fuel pump run for a couple of seconds which should bring the KOEO fuel pressure up to something in the range of 55-58 lbs. Does the pump run?

If the pump does not run, check the fuel pump relay t see if it is getting voltage from signal from the PCM power relay when you first turn the key

 

pumps are good. i just put a new pump in the front tank. i still have 0 psi on the koeo pressure test. and ive tested the regulator and it is good. i noticed today that when i took the gas cap off that it didnt relieve any pressure. could that be the problem or is something else causeing my pressure leak down. truck is a 92 f150 with the inline 6. when running the pressure is in range. i just dont get anything when the fuel pump primes the system. wat else could cause this

 

If you get zero pressure KOEO then the pumps are by definition not priming the system but that does not mean the pumps are the problem. You have two pumps, one in each tank. Does this problem occur on one or on both? If it is both pumps then for it to be the check valve would require a simultaneous failure of the valves in both fuel delivery modules. Unlikely to say the least.

You never answered the question as to whether the pump or pumps run for a couple of seconds KOEO. Failure to do so is not always indicative of a bad pump, can be indicative of problems with the wiring, the power relay, fuel pump relay or the PCM. If it does not run did you check to see if the pump relay is getting voltage? Or if the pump is getting voltage?

How exactly did you test the regulator? Is the 46 PSI running pressure with the vacuum line to the regulator connected or removed. That is way too low a reading for the vacuum disconnected

If the pumps are good, the relays and PCM are good and the regulator is good that leaves a leaking injector. Are any of your sparkplugs gas-fouled?

 

ok. both pumps prime the system for bout 2 seconds. then the relay clicks. and the i only checked the regulator by pullin the vaccum line off to see if gas came out of regulator indicating a bad diaphram. when i did the running test it was when the vaccum line was still connected to the regulator. which puts it in opperating range. indicating a leak down. no my spark plugs are not fuel fouled. i smell no gas or see no gas leaks. truck does not burn rich. bout the only thing i can think of is if the springs are wore out in the regulator causeing it to be stuck open allowing the fuel to drain back to tank even on the fuel prime.

 

So both pumps run and both pumps attempt to prime the system but neither of them holds pressure for more than a couple of seconds? That rules out the pumps, the relays, the PCM and one of the supply backflow check valves. (As I pointed out before having both fail simultaneously is possible but very, very unlikely.)

That leaves the injectors and the FPR.

Take a small pair of vise grips and a strip of leather. Find a spot on the flexible part of the fuel return line (under the plastic sheathing, you just have to slide the sheathing back out of the way) and carefully clamp the flexible return line closed. Do not put bare metal vise grips on the line, use the leather to protect it from damage. Get as far from the nearest metal end fitting as possible.

Run the KOEO test again and see if the system holds prime. If it does, the regulator is FUBAR. If it does not then it is almost certainly an injector leaking

 

Have you checked the spring tension in the igniton switch located at the bottom of the steering column? When you turn the key, inside the column you're using a lever to push a rod that goes into that switch. The lever & rod are made out of really cheap "pot" metal and have been known to break. To view those, one needs to remove the steering wheel. That switch has some adjustment range as well, so it may have just gotten pushed toward the floor a few milimeters and shazam, intermittent starting problems.There was a recall on those switches, the one in my '89 F150 has been changed 3 times in 20 years, I finally bypassed it and put in a starter button. Turn the key, hit the button, cranks every time.