Need Help

[Cb29]

I just bought a 87 Ranger and it ran fine for a week. then it started to idle hunt a little bit but would smooth out. Now It's hard to start you have to cycle the key 6-7 times. I tried to prime it it started in 2-4 key cycles. But then when it running it's rough only at idle but when it's at 70-75 mph it if you let off the gas and try to get back on it i doesn't do anything then it will die but start right back up and be fine. Any help will be appreciated it because i'm lost now.

 

[Earl43P]

I'm fairly certain that your 87 has two fuel pumps.
One is in the tank, it is a low pressure lift pump.
The other is on the driver side frame rail, it is the high pressure pump.

Figure the frame rail pump has to be working if it runs.
The lift pump in the tank delivers fuel to an accumulator so that the high pressure pump can produce flow and pressure. I'd suspect yours is bad.

You could disconnect the fuel line at the fuel filter and and disconnect the connector for the high pressure pump. (some fuel will trickle out of the open filter line from gravity)

Turn the key to run, you should be able to hear the in-tank pump run for 2 seconds each time you go from Off to Run (not crank). Fuel should flow out of the line from the tank pump pumping.

If not, replace it. (and the fuel filter while you are at it)

 

[RonD]

I would also replace the Fuel Pump Relay, it should be on the Passenger side wheel well(engine compartment), there will often be 3 relays in a row, green one is the Fuel Pump relay.

The Fuel Pump relay is a common Ranger failure as they get older, usually they just stop working and you are "dead in the water" but intermittent could be a precursor to total failure.

If you have someone to help you you could test it by turning the key on and off a few times with your finger on the relay, it should come on each time key is on and then go off after 2 seconds.
If it misses coming on once then replace it.
But if it is the original relay then I would just replace it as general maintenance, like the fuel filter.