Hi,

I was driving home the other night and the truck stalled, then took several minutes to restart. After shutting it off at the house, it would not restart. I checked the fuel pressure and there is not at the schraeder valve. I also noticed there was no pump noise when the key is turned on. I hooked up a code reader and it is giving me 21, 24, and 96.

21 = Cooling temp sensor out of specified range or ECT out of range
24= Intake Air Charge Temperature (ACT, AIT) Sensor or Vane Air Temperature (VAT) sensor out of range
96 = Fuel pump secondary circuit fault / High speed fuel pump relay open

Since 96 dealt with fuel, I changed the fuel pump relay, but had no change. I have also checked all of the fuses in the panel.

Anyone seen this before or have an idea what the problem is?

All help is greatly appreciated.

JD

 

Do you have dual tanks? My '88 does and the front tank pump went out from running it dry every now and then. Luckily I had a rear tank that I would run the truck on. The big high pressure pump on the frame will not pull fuel from the tanks. You can hear this pump when you turn the key on. You can't hear the pumps inside the tanks. I'm thinking you have one of these two pumps out but I'm no truck professional. I usually just break two things when fixing one.

 

Thanks, the front tank is out, but it's been that way for awhile. After pulling my hair out for a while (what little I have left) I found one of the wires in the fuel pump relay socket was corroded completely. I repaired the wire and it's running great again.

JD

 

I also have an 89 5.0.

Is the relay up in the engine compartment?

I have the same symptoms as you did with the stalling, and non-starting, and getting no prime noise when the key is turned on .....

Thanks........

 

I have an 1988 F-150 Custom, great truck (bought it in 2000), 115,000 miles and still going strong. My rear gas tank began to leak...it also sits right above where the spare tire sits. Someone once told me that that model was recalled becasue the tire wold rub on that tank...and validity to this?

 

Fuel pump relay would be my first guess. If I remember correctly, it's on the passenger side under the hood.