I'm having trouble with my '88 F150. It has the 4.9, M5R2, and is 4 wheel drive. My truck won't start at all. When I pushed in the schrader valve on the fuel rail, it seems like air comes out but no fuel. I hooked up my fuel pressure gauge, and after a couple times of turning the key on and off, it can only build up about 12 psi. I kept messing with it, and still only air will come out of the schrader valve.

Just for a shot in the dark, I changed the fuel filter to see what would happen, and it still does the same thing. With the one fuel line disconnected, I turned the key on, and sure enough it pumped fuel out of it.

It has been under 32 degrees around here for the last couple weeks, so I'm wondering if ice could have something to do with it. Any ideas for stuff to check out?

 

do you have dual tanks? if so the selector valve may be froze up. when you installed the fuel filter did you make sure it went the proper direction?

 

Yes I probably should have mentioned, it does have dual tanks. And the fuel filter is in the right direction. Changing the fuel filter had no effect on the situation.

I did some more messing with it, I used the diagnostic connector to keep the pump constantly on, and the best it could do was 20 psi at the fuel rail. The pump on the frame rail is certainly running. I noticed the in-tank pump at the rear is much louder than the one in the front tank. I'm not even sure the one in the front tank is running. But I get 20 psi from both tanks. It does take quite a while to even get to 20 psi too..probably 20-30 seconds.

Before all this happened, the truck did run fine on both tanks. I didn't get to check voltage at the fuel pump itself, maybe I should do that, but it was a little to dark for that. Is there anything that likes to freeze up on these trucks? Anything I could try to thaw with a hairdryer?

 

check for a kinked fuel line if there o.k. even if the high pressure pump is running it may not be running proper. also as mentioned by another if your fuel selector valve is sticking part-way this would allow fuel to be re-routed to the other tank and drop pressure.

 

I just did a bunch of work on the truck, so maybe I did kink a fuel line...I'll have to check things out some more. If I can't find anything, would it be ok to try to push some compressed air through the fuel system via the test port? I feel like something may be plugged up with ice. I just wish it was warmer out so I could rule that out. I'm considering changing my high pressure pump on the frame rail...it looks pretty beat externally. Very rusty. Maybe the connections are bad too.

What throws me is how long it takes for fuel pressure to build up...pressure should build in a second or two at the most...but it's taking so long. I feel like there's a restriction but I have to think of a way to handle it.

 

you can rule out ice right now. unless you have a whole ****load of water in your fuel then theres a 90% chance nothing is frozen up. try the selector switch as mentioned. also do voltage drops on all 3 pumps. also check your fuel pressure regulator, if its bad it could lower your fuel pressure

 

Ok so after much work, I've come to the conclusion that most of my fuel system was seriously screwed. So, I started with the dual function reservoir, since I broke it trying to untwist a line. Also, I knew it was draining into the front tank, since the rear tank was empty. This did help. It actually started getting fuel at the rail mixed with air pockets, instead of just air. But no start. It was at like 20 psi.

So then, I changed the frame rail fuel pump, since it was easy to do, and the old one sounded like it was on its last leg. This helped some too. Now I was getting 30-40 psi fuel pressure. It still took like 30 seconds to get there. And there was still air coming out of the port mixed with the gas.

Next, I knew my front fuel tank had a small hole, and was dripping gas slightly. So I decided to just get a whole new tank. The in tank pump in the front tank did not run, the gauge sending unit didnt work, so I replaced the whole sending unit w/ fuel pump. Now the truck runs. Now I know my rear in-tank pump is bad as well, although I can hear it running.


I picked up the sending unit and 38 gallon replacement tank for the rear, that comes with all the hardware to make it bolt in and work properly. I'l be rolling around with 57 gallons of fuel capacity. And i'll be keeping a spare in the bed, plus a fix-a-flat can in the cab just in case I need to leave the spare behind to carry stuff.

So to make a long story short, at the least, my in tank pumps needed to be replaced along with the reservoir. I will note, that there was definitly water in my tank once I had it down. I'm not sure how much, but I could see it separated from the residual gasoline that was there after I drained the tank. I'm not sure if this screwed things up for sure, but it was there

 

Glad to see things are on the up and up, even though the funds go down and down. You should be good for another 200k at least for the fuel system (if injectors don't fail)

 

The truck so far has been a money pit, but I pretty much knew that going in. I'm looking at making it as reliable as possible. The way I look at it, It'll always be cheaper than buying a brand new truck...even one that only costs $20k...especially after financing. I'm maybe $3000 into the truck, including the purchase price. But I have a truck that's in almost-new condition, and in many respects could be better than buying a brand new truck. The list of new parts is pretty big.

I will say, this is hands down the most involved fuel injection system I've ever seen, which is pretty intimidating when something goes wrong.