4.9 takes a long time to start

[rameam]

Not long after purchasing this F150, I discovered that once in a while I would have to turn the key on and off 3 or 4 times to get it to start (I'm wondering now if it was actually that action that readied it to start). Over the years it has gotten worse, lately to the point that I have to drag out my roll-around charger/start booster to get it running.

I thought I had narrowed it down to the check valve in the fuel pump, so I spent five hours Thursday installing a new pump. Started fine and ran better than it had in years.

Next morning I went out to check it, and it started right up and ran like a champ. (Before installing the fuel pump it would run very rough up to about one quarter throttle. As it warmed up, the lower the rpm range of rough idling, until finally there was none. However, if I goosed it up to high rpm while driving in lower gears, it would cut out.)

This morning (Saturday) I went out to drive it to the station to put gas in it, and it wouldn't start. It did just like it had done before. I dragged out the booster and cranked and cranked. (I did check again for firing - plenty of spark.) I noticed at first, the fuel pump would run constantly with the key on. Later it would run a few seconds then shut off. I tapped on the fuel pressure regulator (which I plan to replace next), checked for pressure at the pressure relief valve - all to no avail. I did notice the sound of gas spewing through the reg valve when the key was on. Don't know if that's normal or not. The diaphram is good.

Now, the way it usually happens, and did so this morning, after many attempts to start it, I try again and it fires right up just like there was nothing wrong. After it started, I pulled the vacuum line to the reg and it didn't seem to make any difference. Don't know if that's normal either.

I'm stumped. I realize this is a little lengthy, but wanted to give as much info as possible. I hope someone can help. Thanks in advance.

[ModMech]

If you pulled the vacuum hose off the regulator and it did not run worse, the regulator is bad, even if the diaphram does not leak.

Removing the vacuum hose increases the fuel pressure (low vacuum = higher fuel pressure). It also causes a vacuum leak that tends to lean our the engine.

I think you are on the right track with the FP regulator, especially if there is little or no pressure at the schrader valve when this happens.

[rameam]

Thank you. I did close up the vacuum port with my finger. There did not seem to be any difference after the port was closed. I thought there should be, but had no experience with these valves. I don't have a pressure guage, but will try to locate one. Will reply back afterward.

[rameam]

Well, I've replaced the fuel pump and fuel pressure regulator. Still does the same. I have searched the net for a cold start valve, but no one seems to have one. Does this engine even have one? It must have some type cold start mechanism.

I read there is a timer control associated with it that only heats up when the key is in the start position, which seems to fit my problem. I also read about a man who unplugged his and his vehicle starts right up. So, after I crank on mine awhile, it heats that contact and turns off the valve.??

I don't know where it's located, but going to search some more. Any input will be greatly appreciated.

[rhandwor]

What year is this truck? Did you replace the fuel filter and sock on the in tank fuel pump. Certain fords have a primer pump in the gas tank and a main fuel pump and filter back by the gas tank. If you replaced the main pump, filter and the booster pump isn't working it will take you time to prime the pump. The only I way I know to test it is remove one end of the rubber hose suction to main pump and put a coffee can under it have some body try to start and check for fuel. It only pumps 3 or 4 pounds of pressure.
Otherwise check the injectors with a noid light.
My 1984 T-B with a 5.0L was like this.

[rameam]

I thought I had this thing fixed with a new fuel pump, filter and regulator. Since my last post, I have replaced the plugs, wires, dist cap, rotor, and coil. It will start now if I don't let it set more than a day or two without starting it. I sure would like to know what the problem is, so I don't have to keep starting it. I'm afraid to go anywhere in it, fearing I might be stranded.

rhandwor:
The truck is a 1991.
I replaced the whole fuel pump unit. There is no primer pump.
I have no idea what a noid light is.

I have not as yet replaced the unit in the distributor, though I don't think that is the problem. I was reading in another post that it could be the idle air control valve or the idle speed control solenoid. It seems that it might have something to do with the cold start mechanism, whatever and wherever that is. It's not an extra injector. I don't know where it is or how it functions.

I hope someone has the answer. I'm bumfuzzled.

[rhandwor]

A noid light plugs into the connection for the injector it just shows pulse to the injector. If your temperature sensor is out of calibration it will tell the engine it is hot instead of cold. I would ohm yours in the morning then go to a parts store and ask to ohm a new one. If their is a lot of difference buy a new one. Auto zone or advanced will test your module for free. This is on the side of your distributor. Put a 12volt test on the coil negative it should blink when cranking if dim replace pickup in dist. You have a eec relay in right kick panel a ground wire should be close by a loose ground wire will cause this problem.

[rameam]

Originally Posted by rhandwor

A noid light plugs into the connection for the injector it just shows pulse to the injector. If your temperature sensor is out of calibration it will tell the engine it is hot instead of cold. I would ohm yours in the morning then go to a parts store and ask to ohm a new one. If their is a lot of difference buy a new one. Auto zone or advanced will test your module for free. This is on the side of your distributor. Put a 12volt test on the coil negative it should blink when cranking if dim replace pickup in dist. You have a eec relay in right kick panel a ground wire should be close by a loose ground wire will cause this problem.

Thank you for your reply. I'm not sure I'm understanding all you said. I should check my temp sensor with an ohm meter? What is on the side of the distributor? I have a module inside the distributor. Is that what A/Z will check free? What is the function of the eec relay? How and when does it do its job?

Oh, for the good ol' days, when we didn't have all the sensors, relays, computers, etc..

[rhandwor]

The module is on the side of the distributor. The module Advance will test free.The pickup is on the inside of the distributor. The pip fires your coil this is why a test light will blink when trying to start. It has a magnetic switch which opens and closes like your points. The eec relay supplies power for the fuel pump relay and the computer system. The ground wire if it is loose the fuel pump won't start always. This is the ground for the computer system so be sure and check it. The resistance in the temperature sensor tells the computer what the temperature is so it can determine fuel mixture.

[rameam]

Thanks very much rhandwor. I'll check all this out tomorrow. Let you know how it turns out.