Hey guys,

A few years ago I bought a 1996 F150, with a 5 speed and straight 6. I had it for two years, then I sold it because I needed something bigger. When I sold it, I could not get it the emission systems to ready up for the inspection. The guy who bought it tracked that down to a cracked air tube, and he took it all apart to replace. Once he got it apart he found out he had a baby on the way, and realizing he didn't have time money (and realizing he isn't a great wrench turner) I wound up buying it back very cheap.

I got the air tube, and put it in. I also got everything else back on. Luckily this is a pretty simple engine, because putting something together that somebody else took apart can be a nightmare. Actually, the vacuum lines where a nightmare. I spent hours looking online trying to figure out the routing, then my buddy spotted the diagram on the hood Before I had the lines figured out it would shake violently, then after following the diagram it still shakes some, but I don't know if it is a different issue.

I got them hooked up to what I believe is the correct routing. However, I am still having issues. Before I list the symptoms, I will say that I am not 100% sure it is a vacuum problem, so keep and open mind!!

When you first try to start the truck, it fires right up. Once it is running, it runs well for about 30 seconds, then develops a miss, and the engine starts to shake. It will stay running for as long as you let it; however, if you shut it off by key, it will not start for several hours. Then when it does start again, it goes through the cycle I just listed. I have tried to test drive it, and it has almost no power.

Also, it has a new coil, new rotor, cap, plugs, plug wires, and some miscellaneous parts that don't really pertain to the problems, so I wont list them.

The truck did sit for about a year, could it be a simple case of clogged fuel lines? Maybe a stuck or gummed up injector? While it was sitting the tank was on empty, and I filled it up to half of a tank with fresh gas.

I am really trying to avoid dropping the tank, since the straps and bolts are not looking too healthy; however, I am willing to do it if you guys think that could be the issue. I am not sure where to take my next step, so any advice is appreciated!!

 

during the next 'cranking-no start' period, i would check for spark and test fuel pressure.
1 year old gas is very suspect but i would check spark and fuel pressure first, along with pulling codes, long before i would drop the tank.

 

How do I check fuel pressure?

 

At the fuel rail schrader valve with a fuel pressure gauge. https://www.google.com/url?sa=t&rct=...DiXRUgZtlZ7Ydg

 

You can also try what i have to do, when it runs and you shut it off it wont start again, put your foot to the floor on the gas, mine needs that some days.

 

I tested the fuel pressure, I read that key on, engine off should be 50-60 psi, and key on, engine running should be 45-60 psi. Is this correct? I rented a tester at autozone and hooked it up. When I turned the key on it slowly built up to 10psi. It started right up like usual, then when it started it quickly went up to 35 psi. I shut it off, and it held at 35 psi. I waited a few minutes and when I tried to start it again , it went down to around 25 psi.

clogged fuel lines or filter? maybe the pump?

 

I have tried that, it does not help.

 

A 6 cylinder engine needs at least 45 PSI to run correctly. 35 is way too low. Start with the easy things first....filter.

 

I got a new filter, and one of the quick connect fittings wouldn't come apart. Who knows when the filter was last changed, so it was pretty stuck in there and I would up having to get a new fitting. It should be here on Tuesday and I will update you all then! Thanks for the help!

 

Autozone had gotten the wrong part, so they finally got the correct one yesterday. It wan a little better, but not much. I bought a 94 f150 cheap because it was rolled. It still runs great and everything, so I got it to part out, and take a few things for my truck. It has a 300, and 5 speed just like my truck, it is the same truck just a different color. I decided to take the fuel pump out of that truck, and switch it with the one in my truck. It did not run any different when I switched it. When the pump was in the parts truck you could hear it running when the key was turned on, but not in my truck.Neither the old pump, or the new pump can be heard running. Maybe a mouse ate a wire or something?

 

The fuel pump is energized for 1-2 seconds when cycling the key from the Off to Run position. This is by design. If your parts truck kicked on the pump and stays on, it most likely has a bad computer (common failure mode symptom) or the fuel system wiring may have been molested.

 

Yes, I just listened more carefully in my truck, and like you said the pump goes on then off after a second. I imagine the old pump probably did that too, oh well. At least I know that's not the issue.

Could the injectors be stuck? I know it is a common problem when diesels sit for a long period of time.

 

Any advice or ideas?

 

What is the fuel pressure now with the "new" pump?

Have you ever checked for codes?

 

There are no codes.

Before I did the pump swap I tested pressure again, and it was 0 across the board. I figured the gauge wasn't working, or I had it hooked up wrong, or the pump completely went bad. With the new pump, I tested it and got 0 again. I unhooked it, and hooked it back up, still 0. I brought it back and got a different tester, still 0. Maybe the FPR is bad and letting an pressure go back into the tank?