Have a 94 4.0 ranger and in the morning it starts and runs fine. Maybe a little bit of rough idle for a second but then it's good. Today I was leaving work and it was good and all of the sudden after parking for a few minutes on an incline it would not start. Finally got it to start and it didnt want to idle at all. I featherd it and it started to clear up a little bit. I would hit the gas and get no response and it would just stall out. Changed the fuel filter this past weekend because this has been happening more and more. Was thinking and told a fuel pump. Any other suggestions? Also I checked codes and find it had the fuel pump secondary circuit code.

 

It could actually be the fuel pump. Can you check the pressure at the fuel rail? There is a Schrader valve at the front passenger side that you can screw a gauge onto. It should read steady around 30-40 psi. The better test is if you can watch it while under load; it should stay around 40 psi.

Sometimes, when the fuel pump is dying, it gets noisy instead of having a smooth whine. Replacing it means dropping the fuel tank, obviously.

 

I had problems with my Ford Escort (same basic fuel system) a month or so ago and rigged up a pressure gauge into the car. Very useful for diagnosis. I could see that the pressure took too long to come up when cranking, and the mysterious random "hiccups" on the highway at speed were coincident with momentary drops in fuel pressure.

Being able to monitor fuel pressure while driving is really useful for diagnosis but I believe it may be illegal or at best, unsafe to have a mechanical fuel gauge in the cockpit of a vehicle. Perhaps one could be temporarily rigged up on the cowl.

 

Right. You don't want pressurized fuel in the cockpit. For many years, the Mustang aftermarket tried to sell a fuel pressure gauge that used an isolator that had the pressurized fuel on one side, kept outside of the firewall, and the other side used antifreeze to drive the gauge. They were terribly unreliable in that they often leaked the gas into the side that was supposed to be isolated, and they were very inaccurate.

I was trying to figure out a way to adapt an electronic sensor, like an oil pressure sensor, to drive an electric gauge. Did not look hard enough for the adapters, so it never came about.

 

Another feature of the gauge mechanically connected to the engine is that it telescopes engine sounds. You can readily hear detonation as sharp raps, and even here when the injectors shut down on deceleration.

An oil pressure gauge connected by a copper tube will also telescope the sound, without the problem of spraying gasoline inside the car in case of a leak.