hey all i am needing some help on my 87 f 150
i only use my back tank and since my front one does not work that said i am wondering why every once and a while it will be running fine and just shut off then whn you crank and crank and crank it does nothing it is not getting fuel it does not matter how much is in the tank. its the 4.9 I6 whn you turn the key you hear the pump just fine it you keep messing with it the truck will eventuly start
has me stumped i have no clue it does not make anysence
thanks ..colby

 

Fuel pump relay and/or the wires leading up to and away from the relay...

 

thanks but it has happened like 4 times but it after that its fine then at random it does it but thank you for the suggestion

 

I have a 1988 f150 with a 302 with the same problem and found that the eec relay was shorting out and getting hot and it whould shut the truck off dead so im trying to fix but i feel it is wiring and that is not cheap

 

fordguy300

When it cranks and cranks if you just turn on the key does the fuel pumps run all the time or do they time out in one second?
Check the injectors and see if they are firing while it cranks and cranks.
Use a rod or something long and put it on each injector and see if you hear them go click, click, click.



/

 

when you turn on the key it will run for about 1 or 2 seconds then shut off like i said it has done it 3 times to me and 1once day on dad and it will crank over and crank over then just one time it will fire right up and not miss a beat it does not make anysence it has full power doesn tlug downor anything just a once and a while thing

 

Are you getting fuel pressure? If you are, maybe it is the ignition switch. I have seen switches that will not let the vehicle start while cranking, but when you release the key from start, once in a while it lets the engine start.

Good luck and let us know what you find out.

Dan Harriman 84 F150 lwb
Orange, Texas

 

i agree with kc5gxl in that it could be the ignition if everthing else checks out. my friends has to hold his ignition switch just right or the truck will just cut off.he is replacing his ignition module to fix the problem.hope this helps.

 

thanks i will check these out its not a normal thing it does it has done it 4times since august then it will crank for a min then be fine

 

does this year truck have a reservoir? If you only use one tank on a dual tank setup, then I think the reservoir vavles get gummed up and won't swtich properly. I THINK that the front tnak is the defualt setting for the reservoir/selector, so whenever you shut off the engine, the pressure from the rear tanks drops down and the reservoir switches back to the front tank. Sometimes, when you start the truck again, the old crummy gas in the reservoir and its valves will hold the selector valves to the front tank (while the power is all going to you rear tank pump due to the in-cab selector switch). There are some links on cleaning the reservoir, or you can get a new one from a Ford dealer (i hear the others don't work) for like $125-$150.

I am not sure of the easiest way to check this. Since your problem is intermittent, you can't really plan on when to try something. But, I would say that if the truck does this again when you have a chance to play around, disconnect the lines coming from the reservoir and check to see if there is gas coming out of it. Them check the lines into the reservoir and see if you have gas coming in. If there is gas out of the reservoir, then you have a problem somewhere else. If there is no gas going into the reservoir, then you have a problem with your tank.

When you get this problem, will the truck fire if you spray starter fluid (ether) into the intake? If so, then you have a fuel delivery problem. If not, then I would look to electrical/ignition.

 

Not true.
The center shaft of the selector valve reservoir has a detent in it and will remain locked in the postition of last selected tank while the the truck is not running. His year truck will also have a filter inside the selector valve reservoir.

 

but, the reservoir could still be acting up, especially since he only uses the rear tank.

Are all the reservoirs made the same way as far as the 'off' position is concerned?

 

None of the reservoirs have an 'off' position.
I think the 1987 and newer ones are the same and 86 an older have a Filter in them. I do not think you can put the filter in the 87 an newer ones.
I think they all lock in position but if the boost pump in the tank is weak it may not be able to lock it. But it may move it far enough to line up its tank while it is running.

 

Bill,

by 'off' position, I meant what happens in the 'key off' position, i.e. like you said, the reservoir locks into position. Thanks.

 

i don't mean to be the guy who jumps in and contridicts everyone... where all of the points are valid, you are skipping the valuable diagnostic period... i am a firm believer in diagnostic before repair... combustion triangle, heat (ignition) air and fuel (and compression)

compression is an easy one to knock off, which means that air is also, as they go hand in hand... which leaves ignition and fuel, easiest way to check that, smell your exhaust when it's cranking, and right as it kicks, if it smells like gasoline, you've got an ignition problem, if it smells like clean air, or clean exhaust, you've got a fuel problem, this is a free, easy way to narrow down your problem areas before you start testing individual parts, and when you do, i personally would start at the engine (cylinder) and work backwards, skipping components,

if it is fuel, which it sounds like, check the injectors, make sure they have pressure, check the clicking, and check for fuel pressure at your fuel rail, clicking but no pressure in the rail? go to the inline pump, check for function and pressure....