Why is it every time I borrow something I end up working on it?
I need a little help here guys, I'm a diesel mechanic that knows very little about gasoline fuel injection. I borrowed a friends 89 F250 bucket truck and now it refuses to run. It is a 460 EFI. At first it acted like it was starving for fuel, but would run as long as you kept playing with the accelerator pedal. Now it will attempt to hit when you first turn the key, but will not run.
I have checked and am getting fuel at the schader valve on the fuel rail. It seems to have good spark at the plugs.
I need to get this thing running so I can hang trusses for a roof-over for my trailer and then return it. Any help will be greatly appreciated.

 

Bad fuel pump... do you have a pressure gauge for EFI? If it is that, tow the truck back to him!! It's a job...

 

Same result from both tanks, so I wouldn't think it would be the fuel pumps. I can hear the pump cycle when I first turn the key on also.
No gauge, so I have no idea what the fuel pressure is.

 

Is the Check Engine light on? Maybe you can pull some codes?

 

I use a squirt oil can full of gas to check them. I would try squirting fuel into the intake and see if you can keep it running to make it positive it is lack of fuel and not a electrical issue.
The just have to back check the fuel system. I think on the dual tanks they still only use one filter. It is usually along the frame rail. The ecm is not very smart on those trucks so for the most part plugging a scanner into then is not too helpful
Good luck
Larry

 

Well, it is definately fuel related, it will run on starting fluid sprayed into the intake. Fuel pump on the frame is working, filter is clean, pump in front tank is inop, but the rear tank will still supply fuel. Gauge says rear tank is almost empty and what fuel is coming out smells "bad". I'll put some fresh gas in the rear tank tomorrow and see if I can get it to run. Worst part is, the front tank is almost full

 

Isn't that the way it always works?

I'm not sure but I would gues that when you switch from one tank to the other that the switch, besides controlling the fuel gauge, switches the fuel pump also. I mean it wouldn't make sense for the tank thats not being used to have its fuel pump running all the time.
so, you might try fiddling around with the switch, work it back and forth a bit. Does the pump in the front tank try to do anything? Here's another last ditch effort. You might try whacking the heck out of the fuel tank with someone cranking the engine over (this is easier if the tank does not have a skid guard). Sometimes you can "coax" the fuel pump into at least trying a little bit.

Changing the fuel pumps is not horrible, but its not easy either, especially with a full tank. If you can get the pump to run even a little you could use it to drain the tank into a storage container. There might even be a jumper lead up under the hood somewhere to hot wire the fuel pumps (at least there is on GM vehicles).
If you do have to buy a fuel pump DO NOT skimp and buy one of the cheapos from Autozone, Oreilly, etc. Go to NAPA. their electric fuel pumps are manufactured in the US by Carter.
After going through 3 fuel cheap Autozone pumps in my sons Ranger in less than 2 months I learned that lesson.

You can probably "borrow" a fuel pressure gauge from Autozone, Oreillys, etc. but it sure sounds like you don't have enough pressure. When you depress the schader vavle and kit the key and/or crank on it you should get a pretty good healty spray of fuel out of there.

Good luck
Bobby

 

I'd bet on the switchover too. If you can jumper the front tank fuel pump to battery, and it works, there ya go.

 

Picked up a cheap fuel pressure gauge today. I have maybe 5 PSI of pressure, not nearly enough for the injectors. Guess next step is to jumper the pump and see if I can get it to run.

 

Good luck Jeff. I hate EFI.

 

OK, jumpered the front fuel pump, it runs! Pressure came up to 38 PSI, just where it should be. Cranked the engine and I still have exactly the same problem as before It will run as long as you are steadily pumping the accelerator, sorta like keeping an old cold natured carb running when it has a vacuum leak. Will not rev or idle.
Give me some more ideas here fellows, I'm at a loss

 

Is the cat still on the truck and could it have come apart blocking the exhaust. The cat on my 1990 F-350 with the 460 broke apart internally, blocking the cat. It would not run much above idle but it would idle. I chased my tail a while before I found it.

 

It's not throwing any codes? Does the check engine light work? There should be a way to jumper some pins and get it to flash the codes.

Could be a plugged cat, but normally it would start and gradually choke off if that was the case.

Vacuum leak, throttle position sensor gone bad, temp sensor gone bad (less likely).

 

No check engine light, but who knows if the bulb is good. Don't think the cat is plugged, the exhaust sounds too loud for that.
Unless the accelerator pedal is being moved, the engine shuts off like it runs out of gas. no sputtering or anything, just dies. Don't think it's a vacuum leak, it would still rev up if so. Throttle position sensor is what I am leaning towards, but don't want to start throwing parts at it and hope that fixes it.

 

I'm not too familiar with the Ford EFI set ups. Is this a throttle body type fuel injection or does it have individual fuel inejctors?
If its the type with individual fuel injectors then you might try looking at whatever sensor tells the computer how much air is coming into the engine. GM calls this a MAF or Mass Air Flow Sensor. Basically the computer needs to know how much air is going into the engine in order to supply the correct amount of fuel. If youcan identify this sensor and tap it gently with the handle of a screwdriver it might alter the way the truck is running; either kill it or make it smooth out, etc.

Again, I'm not completely familiar with that particular EFI set-up so I'm just grasping at straws here.
Bobby