taylorethomas87

Alright, so I'm new to the forum. Ill give a bit of my background quick. Ive always owned older vehicles because I love working them. I went through automotive school, and decided I didnt want to do it as a job anymore. Its been about a year since ive been out of school, but ive done some tinkering since then.

My problem is....my 1987 Ford f150 Lariat with the 5.0. It's always run grwat. Only about 100,000 miles on it. This morning on my way to work it did. And just wont start. Had it towed home. Basically,Ithe engine will crank, fire up and idle rough. If I hit the gas it dies instantly. If I don't touch the gas it will slowly die, in about 5 seconds. I've replaced the fuel filter. The fuel that came out of the filter was a light rust color. That has me worried. When I check the fuel pressure on the fuel rail with a screw driver the fuel just kind of pours out. Seems like there is barely any pressure. My experience the fuel should almost spray out. Any suggestions?

Rusty but trusty

Fuel pump is clogged up and / or failed. Probably time to drop the tank if you see rust in the fuel lines. And yes, with the fuel pump energized you should be spraying all over not just running out, get a gauge and check it anyway. My bet is you need a new pump and at the very least clean out the tank.

flareside_thunder

Check pressure at the rail for starters.

rikard

IIRC the 87 has two fuel pumps, one in the tank and another on the frame rail under the cab. The tank pump is a low pressure unit and the frame one is high pressure.
Regards
rikard

taylorethomas87

Pressure at the rail is incredibly low. I seem to have misplaced my pressure tester, but I know it's not high enough by how the fuel comes out of the pressure tester.

Rusty but trusty

So that leaves your regulator or one of the two pumps, the fact that you said the fuel in the filter was rusty leads me to an in tank issue, the pickup for the pump could be clogged.

taylorethomas87

Thankga guys. I work until 4pm CTZ tomorrow and will dive a bit deeper. Can a bad fuel pump cause my truck to die when the gas is hit?

Rusty but trusty

Yes, the fuel pressure, rather flow required for idle is low, when you hit the pedal you are requesting much more air which makes your computer want to dump in much more fuel, with a weak pump that fuel is not available and the engine dies..... Basically you either have a failing pump or some restriction to the flow.

flareside_thunder

^^^This. It could be either one of the pumps that is faulty. Need to test them individually.

Just call me Sean

iTrader: (1)

Three fuel pumps if you have two tanks. If it runs the same way on each tank (if they both used to work) then the high pressure frame pump.