Hey All .... new to the forum here. Thanks for having me.

I'm working on one of our fleet vehicles here, a 1995 Explorer. about 2 months back, it stalled out. Got it back to the shop and turned the key on .... I couldn't hear the fuel pump. I replaced the fuel pump and the fuel pump relay. Vehicle started right up and seemed to run O.K. About 2 weeks ago, it stalled out again, same symptoms, acts like it runs out of gas and can't hear fuel pump.So, I have been playing with it and find that it starts up great in the cool mornings. In the afternoon when the temps are hotter, it won't start (can't hear fuel pump). The following morning when temps are cool, it will start right up and can hear the fuel pump. I almost wrote this one off as a defective fuel pump, but I'm not sure on this one. Does anyone have any ideas or suggestions?? Thanks in advance for any ideas you may have. Timm ....................

 

I'd grab a voltmeter/test light and a wiring diagram. Next time it won't start, check for power at the inertia switch (because it is convenient). If you have 12 V at the inertia switch, then check for power at the fuel pump (on my '92, the fuel pump connector can be accessed in the driver's frame rail above the rear axle, so you don't have to drop the tank). If you don't have power at the inertia switch, then move up to the relay to see if the relay is closing.

 

Thanks mrshorty .... I'll give that a try. Of course, right now it is starting. I'll move it outside and let it warm up abit. Thanks!!! Timm .......

 

Stop replacing them with cheap fuel pumps, I had a similar issue. Every, and I mean, every aftermarket fuel pump I have used in my Aerostars did the exact thing you are describing. The aftermarket fuel pumps would probably work ok for a car that was not used much, maybe drive to work in the morning, drive home in the evening. But for extended length drives, the aftermarket pumps frizzle out. The pump literally overheats and shuts down. My factory Motorcraft pump lasted 168,000 miles or so in my '94 Aerostar. By the time I reached 100,000 miles, I had been through 4 aftermarket fuel pumps, 3 of them left me stranded out of town. I spent the extra to get a genuine motorcraft one, got improved throttle response, better gas mileage, the pump ran quieter, and never had a problem again until the van got totaled, 38,000 miles later.

On my '97 Aerostar, I decided to go with an aftermarket again, thinking maybe try a different brand and a performance oriented pump. A week and a half later, I had to pay a mechanic to fix it while I rented a van to the tune of $380 dollars to finish my business trip. The mechanic installed a Motorcraft pump, I haven't had an issue since.

My solution, genuine Motorcraft pump, problem solved. The aftermarket pumps are not built to the correct specs, they overheat and fail.

 

mrshorty ..... o.k., I was able to catch it when it wouldn't start. I checked the 4 pin plug @ the l/r axle. I got no reading on 2 pins, almost 12 volts on one pin, and almost 10 volts on another. The ones I didn't get a reading on I am assuming are ground???? The one pin with the lower voltage I'm assuming is the fuel gauge, and the higher reading is the pump???? So ....... the pump SHOULD be working, correct ?????

 

It sounds like it. If you can confirm that it has power and ground, and the pump won't run, then something is wrong with the pump.

 

In my experience, the pumps were getting full power. Most aftermarket pumps now are built from the same factories in China. Not saying that Chinese products are automatically junk, but products made by the low bidder are.

If you want a pump that works correctly, you really have only 2 choices. Either a genuine Motorcraft, or a Carter (they make most Motorcraft fuel pumps). The other brands are basically garbage, and do not operate properly at operating temperatures.

 

On your 1995 Explorer, the Pink/Black wire is the power feed from the inertia switch to the pump. The black wire is the fuel pump ground. The black/yellow wire is the ground for the sending unit and the yellow/white wire is the sending unit to instrument cluster gauge signal.

If you confirm that when you first turn the key on you have battery voltage at the connector between the pink/black and black wires the pump is getting voltage. If the voltage is a volt or two lower than battery voltage, the issue may be a high resistance path (dirty/corroded connection) between the inertia switch and the pump connector. This is assuming you are unplugging the connector to make measurements versus back probing the connector.

-Rod