You should have a shrader valve. Keep looking. I think mine is on the drivers side rail, closer to the front of the engine.

 

I know it sounds a little crazy that I don't have one, but I did some searching around online and a few other people have also complained about the same thing; here's one here -- also this poor guy here.

They both appear to have the same truck as I do.

Is the valve somewhere else?

 

alright... I'm back. Things are looking grim.

Sigh...

So I bought the fuel pressure tester adapter thingie which let me hook up a T (basically) to the output of the fuel pump on the frame. So I connected up the pressure guage and turned the ignition key.

(bear with me this gets confusing)

I got nothing on the pump... nothing, even though I could hear the pump running. I'm pretty sure changing tanks changed the tank pump properly, because they sound a little different (one is a bit louder than the other). I tried starting the truck and it started right up, the pressure came up to about 20... the truck ran rough and I killed it. Pressure held at about 20. This time when I turned the key to on the pump pressurized to about 80 psi!!! I started the truck and it immediately fell to about 40, but then skyrocketed up to 80 or 90 again. A few more tries produced pretty random affects. Sometimes the truck would run around 45 (which is the closest it ever got to running right), sometimes it would fall off slowly down to 0 (and die), sometimes it would float around 20 and then shoot up to 60 or 70 or 80, sometimes I couldn't start it and the pressure would stay at 0.

OK, so I just changed the fuel pressure regulator a few weeks ago, but I know I have a vacuum leak -- my brake booster is leaking; I can hear a hiss from the cab. I put a vacuum guage on the truck and it was running between 13 to 17 inches of vacuum... too low. I figured that maybe if the intake wasn't pulling enough vacuum that the pressure regulator wouldn't be working properly resulting in the pretty high fuel rail pressures (I can't explain the low pressure values unless the pump is also bad). So I pulled the hose to the brake booster and plugged it, and still got like 15 on the guage, so I disconnected other hoses.... i ended up disconnected all the hoses (except for the pressure regulator) and there was still only something floating between 12 to 17... but the truck never really ran very well. Are there any other vacuum lines coming off the intake other than at the center top?

Anyway... so about at this time I started noticing a "drip drip" sound when I would shut the truck off. At first, I thought it was the T I put inline my fuel system but there wasn't any gas on the floor.... I ran the truck, shut it off, and listened for the drip drip... and determined it was coming from my oil pan -- which is completely awesome. So I pulled the dip stick and sure enough... gas in the oil.

So now all of a sudden I seem to have a leaking injector... or a lot of leaking injectors. I could run the truck (but after this point I didn't really want to run it much at all) and hear it dripping -- but the weird thing is that the fuel pressure measured at the guage wouldn't change, it would hold steady at whatever it was after I shut the truck off. So what does that mean? If I have a wasted injector shouldn't the pressure bleed down because it's dumping all its fuel into the cylinder?

Anyway, I'm pretty worried at this point. I drained out the oil and it smells pretty heavy of gas. I swear that I hadn't heard this gas dripping thing before tonight, but I can't see that I did anything to cause the high pressure in the fuel line.

I'm completely confused at this point. It seems like I have all sorts of problems. I may have a problem with one (some?) of my fuel pumps because the pressure sometimes stays low. I seem to have a vacuum problem even though I blocked off all the ports at the intake (that I know of), and I have at least one bad injector -- but maybe more? If I can hear the gas running down the inside of the motor it must be a pretty awful leak.

Well... at least I seem to have decent spark.

Anyone have any suggestions what I should do? I really appreciate the help you guys given me so far.

 

the fuel pressure should hold a reading at the gauge after the truck is shut off it does that for easy starting cold so it don't have to prime the entire rail if your oil smells like gas probably the regulator at fault once again leaking fuel into the vacuum port or a vacuum leak at the intake to head seal

 

You may just be hearing oil dripping down, that's what I would expect. The gas in the oil, there could be other possible causes. Don't automatically assume one symptom is directly related to a certain problem, you need to prove it out somehow.

 

well I can say this...
when I turn the truck off the fuel pressure stays solid. The last start, run, stop I did left the pressure at 30 psi about an hour ago, and it's still pretty much at 30 psi now (I just checked it). That would lead me to believe that the regulator and the injectors are holding pressure. I would also say that the dripping sound is unlike anything I've ever heard.... I can't say I've ever noticed it before, and definitely there is gas in the oil now. It smells very strong of gasoline.

I guess I have so many symptoms now I'm not sure what to go back and attack. Should I check the injectors? How do I do that? What about the vacuum leak? Sometimes I get low or no fuel pressure... like just now I turned the key to prime the fuel rail and it just sat at the 30 psi, the fuel pump running didn't pressurize the rail to 40ish (but I heard it run). Sometimes I get crazy high pressure. Does that point to the fuel pressure regulator? Is there a valve somewhere in the return that could be not working or something? How does the return work to whatever tank is selected?

I'm just a little lost.

 

I don't remember where I was reading it the past several weeks over the summer, but I seem to remember having seen that the crzay-high pressure you're sometimes seeing may not necessarily be unusual. Again, I don't remember... was I reading about the Tempo (with CFI)? Or the Taurus? I'll have to see if I can find it again.

Your vacuum readings kind of raise an eyebrow, see if this helps you any:
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Do you have two pumps? Or maybe three? In-tank pumps, and one on the frame rail?

 

I have 3 pumps; one in each tank, and one on the frame rail. The fuel filter is between the tanks and the pump on the rail. I put my fuel pressure guage after the pump on the frame rail. There is nothing on the line after the frame rail pump before the fuel rail itself (so nothing that can cause a restriction on the input side other than the regulator i suppose on the output side of the fuel rail).

 

ctubutis, your vacuum link is interesting. I can check again with that in mind... according to that page, my readings are not too far from ok. It says anything betwee 17 and 22 is ok ... what should a healthy vacuum be for this truck? I've been told something like 22 to 27. Also, the page is talking about a steady low reading could be indicitave of "bad oil". Well, don't I have bad oil? I mean, it's full of gasoline.

Oh and I'm sorry I forgot to add something (not sure how useful it is).
Sometimes... when the truck dies the fuel pump(s?) will stay running. I assume that's not normal.

Are there 2 fuel filters on this truck? Is there one I'm not finding. I found this from a different post about an 86:

"Are you sure it is electrical? The F150's have two fuel filers, the standard forward mounted EFI filter and a paper one. The EFI one is visable and gets changed often, however the paper is buried and does not get changed very often, if at all. This caused what felt like a miss / failure to maintain speed going down the freeway. "

Where is this paper filter? Could that be clogged and causing the high pressures (but only sometimes??)
Could the tank selector return be just... I don't know... "off" and the return doesn't work to either tank?

More thinking out loud... I have about 4 symptoms here so I'll take them each in turn.

1. I get no / low pressure sometimes. I think this must be a pump (or pump control) problem. Sometimes I can hear pumps running (but I can't be positive both are running).... that's one problem.

2. Sometimes I get crazy high pressure... this must be related to the return somehow and not due to the pump, so here I either have some occational blockage or the fuel pressure regulator is not working properly. Correct me if I'm wrong, but I should be able to pickup a vacuum hand pump, prime the rail, and then pump up the regulator to bleed pressure back to the tank right? This should tell me the regulator (that I just replaced) is good.

3. I have low vacuum? Do I have low vacuum? I'm not really even sure about this one yet.

4. I have fuel in my oil. This could either be... injector problems or perhaps fuel pressure regulator -- because I'm told fuel can enter the intake through the regulator; though it seems to be I would hope I'm not getting enough fuel in through the regulator that I can hear it dripping down after I shut the truck off (if what I'm hearing is even fuel).

So I need to test the regulator as step #1. After that it would be nice to figure out what is causing my fuel pressure problems. THEN once I figure that out I can try to see if I have leaky injectors.

 

Man, im a bit confused also. I had some crazy fuel issues with my 86 EFI. What I did was removed the rear tank. Removed the tank selector valve. Now I just run the front tank. I replaced both pumps, fuel regulator and one fuel line that looked chewed up for some reason, and now I have no issues. The Ford dual tank system is the most terrible fuel system I have ever worked on. I just eliminated the rear tank and valve and the pumps now run flawlessly. I was having all sorts of funky things. My rear tank was getting filled up from the front tank and it was gushing gas out the filler neck.

 

I know, I think I'm just confusing myself here. I have codes and this problem and that problem. I think I just need to step back.

to start:

I'll test the fuel pressure regulator with a vacuum hand pump and
I'll check the electric connections on the high pressure pump to (hopefully) help with pressure issues.

I'll do a compression test and see if that sheds light on fuel in the oil issue.

 

Status update.
High pressure pump appeared to be working. I can feel it running but no pressure. I put the gauge before that pump after the filter.
With forward tank pump selected I got barely any deflection on the needle, like one or two psi. Rear tank pump (which worked last week) does nothing when selected. No noise, its dead completely. I can hear the selector valve thing actuating when switching pumps. I'll bypass the filter and see if the forward tank pump is really bad or if its just clogged at the filter.

 

I said to hell with all that selector valve crap. I got a spare tire mount out of an 80 bed to mount the spare, removed the rear tank and selector valve and haven't had a fuel issue since.

 

I'm going to focus on getting the forward tank working first, I think. If that means i have to bypass that selector thing then so be it. I'm looking online to just get an idea what the prices are for these pumps (if I need to buy one) and I'm not really sure which one I need. Does anyone have an idea what the pressure rating should be for the in tank pump? I know that a carb system uses less pressure, but I have EFI of course. Is it the same in tank pump for both systems? So I can't screw up and get the wrong one?

 

This is from the 1986 Engine/Emissions Diagnosis shop manual, I'll see if I can find more fuel system diags in it.