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Rob MacGregor (LAURA LEYSHON/LAURA LEYSHON/THE GLOBE AND MAIL)
Rob MacGregor (LAURA LEYSHON/LAURA LEYSHON/THE GLOBE AND MAIL)

Rob's Garage

Why can't I pump my ride? Add to ...

Question:

Dear Rob,

I'm happy to see that there is a site like this and I am hoping you can helpme with an insidious problem I've been having with my truck since it waspurchased three years ago.Periodically, when I try to start my 2000 Ford F-150 with the Triton V8engine, the engine turns over but won't engage. This happens infrequently,sometimes twice in two days, sometimes not for two months. If it's left fora few hours, it always starts. I have tried to correlate it with theweather, i.e. humidity or temperature, but to no avail. I've checked thefuel and there is gas pumping, and also have replaced the solenoids underthe hood. Using a different key doesn't help either. I've taken it to theFord dealership and private mechanics and no one can help me as it's beentowed in before and starts when they try it. I have a feeling that it hassomething to do with the electronic ignition, but don't know how to go abouttesting it. Any ideas?Thanks in advance and I sure hope you have some ideas,

Doug

What a great word - insidious! I can't say that I've ever heard that word used to describe an automotive type problem. I need to use that more often. This is one of the great things about getting feedback from people, you get to hear new terms and stuff.

Doug, not knowing the time at which you had the fuel pressure tested, I'm going go with the most common problem and that is a failing fuel pump.

I say failing, not failed because obviously the truck's engine starts up semi-regularly. I would hate that because with my luck, I'd need to get stuff done in a hurry and that would be the time the engine wouldn't start - I hate it when that happens!

OK, back on topic. Try this the next time your truck is more stubborn than a north-bound mule headed toward a southern uphill climb. Take the fuel filler cap off and have someone turn the ignition key from off to on. You should hear a buzzing noise from the filler neck...not to worry, this is the fuel pump located inside the fuel tank. (Another day, I'll tell you how you can get away with an electric motor running inside a fuel laden container)

If you don't hear any buzzing, give the fuel tank a whack with a rubber mallet, or if you're in the mood, thump it with the bottom of your fist - please don't use your knuckles!

Most of the time this will start the pump running. If it does, you have two things going for you. First, the pump is running and you get to run your errands or go to work. The second thing is that you now know that the pump is hooped (technical term). What has just happened is that by jarring the tank, you jar the pump. The pump is an electric motor with small contact segments on an armature called commutator bars. There is likely at break in the contact or the armature wiring and by tank thumping, you vibrate the pump just enough to pass the contact brushes to the next commutator segment, causing the pump to run.

Next step - get the truck to a shop for the repair.

Word of advice: If you want to be appreciated as customer, no matter what shop you frequent, please try and take the truck to them with as little fuel in the tank as possible. As a technician, it's no fun to try to remove a fuel tank full of gas. Trust me, spillage happens and at the prices we pay for a litre of gasoline, this would be like a DeBeers diamond cutter moving a tray of diamonds and spilling them all over the floor.

Do you have any maintenance questions for Rob? E-mail him at globedrive@globeandmail.com

 

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