I own a 1989 Ford Ranger with a 1988 2.9L engine installed. Recently I've been having trouble with the truck idling between 1500 and 2000 rpms and sometimes I had trouble getting it to start. I drained the battery today trying to start it. A code reader read FUEL PUMP CIRCUIT BAD. Does this mean that the fuel pump is pumping at high pressure all the time and not switching to low pressure? Has anyone had a problem like this?

 

Try changing your fuel filter before you jump ahead. Blockage (dirty filter) will keep the pump from operating correctly.

 

I changed the fuel filter and it made no changes to the running or cranking of the truck. Thanks Goingstrong for your suggestion. Do you have another?

 

Could be in the actual circuit. Have you looked at the fuses? Sometimes the wires inside the fuel tank can be compromised if your local fuel station waters down their gas. (Let's use that as a last resort, though). Do you have a one wire 12 volt tester? This comes in handy when checking electrical circuits. Especially if there are any fusible links in the wiring to the fuel pump. Sometimes you'll find a loose or disconnected wire under the hood or under the dash. I've even witnessed solder blow off a single component in a circuit board and shut down the works (but that's usually a long shot). Keep in mind the fuel pump isautomatically controlled. What ever part does the speed increase on the fuel pump could have it stuck on fast speed and be flooding it while idling.

 

Is 2.9 the original engine?

 

Today I took the bed off and check the fuel pump out. It checked out OK. The fuel pressure regulator is sending gas back to the tank on a constant flow. I'm not sure if this is a good thing. I could hear the fuel pump whining when I turned the switch on and when it was idling. The pump seemed to have the same pitch the entire time as if it is locked is high pressure mode. When I turned the switch off and attempted to crank the truck again. It had to turn over many times, then it started to fire, sounded like it was running on two cylinders, puffed out black smoke, and finally straightened out and idled at 1500 rpm. What controls the pump shifting from high to low pressure? The original 2.9 was replaced with a 1988 2.9 engine. Thanks again Goinstrong.

 

Is it a stock pressure regulator? If it's the same size engine the electronics should function the same so the year would be no problem. Is the speed sensor OK?