My truck wont't run run worth a crap once warm.

[Albino 94LTD]

Have you replaced fuel pressure relay yet?

 

[RockRanger]

No. My thinking on it is that if the relay failed then I would have zero pressure because the pump wouldn't get any power. I get some pressure and can hear the pump running. Am I miss thinking this?

I am assuming the relay for the pump and computer are the same? Probably wouldn't hurt to pick one up as a spare anyway. My truck didn't have AC or fog lights so I don't have those two relays to steel if one of the others went bad. Pretty sure they are both the original relays as they both say ford on them.

 

[Albino 94LTD]

Fuel pump is separate relay. Switch with WOT relay. If its going bad the voltage will drop and pump wont run full pressure. This happens before the relay quits. Completely.

 

[natenkiki2004]

Fuel pump is separate relay. Switch with WOT relay. If its going bad the voltage will drop and pump wont run full pressure. This happens before the relay quits. Completely.

^^ This. There's examples of methodical testing of this in ScannerDanner's videos but basically the relay is failing and can cause voltage drop. This means a drop in pressure but some function. As the relay heats up, resistance values change and it's likely on the verge. If I were you, I'd grab a cheap parts store relay and swap when things start acting up. If that fixes it, either fork over $$ for an OEM Ford relay or grab several from a junkyard and put them in the glove box.

 

[2stroke]

Since you have the tank down, you might as well replace the pump. Also Its a good idea to change your fuel filter at the same time, and since its so cheap, buy a new relay as well. With those three things you can totally eliminate the fuel pump as an issue. The only other possibilities are a bad FPR, or a pinched fuel line. Since its load/heat related, I'm leaning more towards fuel pump. I doubt you have a pinched fuel line, but just visually check it under the hood connected to the fuel rail. I'm thinking a bad FPR (or missing/cracked vacuum line) would raise pressure, not lower it, I suppose anything is possible though.

I'm having fuel pump issues of my own right now, but I'm confident a new pump, filter, and relay will fix yours.

 

[RockRanger]

Picked up a new pump and relay and will install them tomorrow. I forgot to get the fuel filter part number before I left so I will get it tomorrow. However I am having a hard time finding one part for my fuel tank. It is a rubber grommet that goes into the top of the tank. the check valve breather thing goes into it with a line running to the charcoal canister I believe. See the attached pictures. Anyone have an idea on a part number on it. The truck is a 93 but the tank is out of a bronco II if that makes a difference.

20160702_193610 by Matthew Dresselhaus, on Flickr

20160702_193619 by Matthew Dresselhaus, on Flickr

20160702_193633 by Matthew Dresselhaus, on Flickr

 

[RockRanger]

Installed the new pump, relay and filter, took the truck for a drive and no problems. Roughly the same temps outside as yesterday as well. Hopefully my problems are solved. Over the next few months as I get chances to drive the truck hopefully this issue doesn't come back. I sure would like to find that grommet if anyone has any ideas on what it is called or a part number for it.

 

[damnford]

i worked on my friends 85 f-150 the other day and replaced all the fuel lines to the front tank. he couldn't fill the tank because it would spit back at him. found out whoever worked on the truck before didn't put the vent hose inside the big hose and used fuel injection hose for the fuel line. put regular 3/8 fuel line up to the switch and 1/2 in line inside the big hose. the check valve up on top of the tank was leaking as well and we got the part at the ford dealer for about 8 dollars, just took in the old part and they matched it up no problem.

 

[damnford]

Picked up a new pump and relay and will install them tomorrow. I forgot to get the fuel filter part number before I left so I will get it tomorrow. However I am having a hard time finding one part for my fuel tank. It is a rubber grommet that goes into the top of the tank. the check valve breather thing goes into it with a line running to the charcoal canister I believe. See the attached pictures. Anyone have an idea on a part number on it. The truck is a 93 but the tank is out of a bronco II if that makes a difference.

20160702_193610 by Matthew Dresselhaus, on Flickr

20160702_193619 by Matthew Dresselhaus, on Flickr

20160702_193633 by Matthew Dresselhaus, on Flickr

dealer item, take old one with you costs about 10 bucks.