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The Yankee Express

A little corrosion is enough to cause problems

John Paul

Q. I have a 15-year-old Chevrolet truck with a V-8 engine, and it cranks forever before it starts. I have replaced the fuel pump, fuel pump relay and the computer and it still doesn’t start correctly. I have spent way too much money and my wife said just get rid of the truck. I don’t have a lot of skill with voltmeters; is there something else I should be looking for?

A. Replacing parts without testing circuits can result in spending a lot of money with no results. Start with looking at power and ground to the fuel pump relay. The first place I would start is to look for a grounding block and check the connections. I have seen on multiple occasions that where several items share one ground a little corrosion it enough to cause problems. 

Q. My 2017 GM truck has both low beams out. One day they worked and one day they didn’t. I have a friend with a fancy computer scanner, and he said there were three codes. The codes were for headlight control circuits. What kind of problems am I looking at? 

A. I suspect there is nothing wrong more than the bulbs need replacing. Headlight bulbs have pretty specific hour ratings and they both likely failed within a few days of each other and you never noticed until both failed. Start with some basic testing at the bulbs. 

Q. In a past column, you had a reader that was looking for a mid-sized SUV that had some off-road capability but wasn’t too “macho.” I believe you recommended the Honda Passport and maybe a Subaru. I’m actually looking for something a bit more rugged. I looked at Jeeps, but there are just too many of them. I looked at the Ford Bronco, but there is a long wait and dealers are marking them up too high. What am I missing?   

A. You are correct there are a lot of Jeeps because they are still wildly popular, and some people are paying $10,000 or more for a Bronco. One vehicle that may work is the Toyota 4Runner. This is a solid vehicle that although matured has not lost its truck roots. The 4Runner is very capable off-road and has all the latest safety and convenience technology. The non-turbo-charged V-6 engine may seem dated by contemporary standards, but it makes 270 horsepower and can tow 5000 pounds. The interior is comfortable and the seats supportive. Fuel economy on the other hand is terrible with an EPA rating of 17 MPG combined city/highway. If fuel economy isn’t a concern the 4Runner by Toyota may be a good fit.

Q. I have a 2010 Hyundai Elantra and the passenger side air conditioner vent has cold air coming from it, but the driver’s side is warm. This is a basic car, so no fancy AC system with dual temperature settings. What is wrong? 

A. The first place to start is to inspect the air conditioner pressure readings. At 12 years old the system has probably lost some refrigerant. Since the air conditioner evaporator is located on the passenger side If in fact the system is low on “charge” it is possible the passenger side would be cooler than the driver’s side air. If this is the case, the system should be checked for leaks. If there appears to be no leaks, recharging the system should get the air conditioner fully operational again.

Q. My 2015 Ford Escape has the oil light on. The engine is quiet, and I replaced the oil sender unit with a Ford part and the light is still on. Any ideas? 

A. Although your ear tells you the engine is quiet, I would still want to check the oil pressure with a mechanical gauge. You should see 30-60 pounds of oil pressure at 2000 RPM. In this case I did a little research on AllData (the technical database I use) in their community page. I found a very similar concern. In this case the BLU/BRN wire from the oil sender to the car’s computer was shorted against the engine block near the starter motor. When the wire was repaired, the light operated normally. This would be a good place to start. 

Q. I just purchased a classic 1994 Chevy Caprice wagon for my beach house. This boat of a car is powered by a fuel injected 5.7-liter V-8 engine. It is like driving around on your sofa. I love this car; I can put my wind surfing stuff in it and carry just about anything. The one problem is the engine stumbles, but never stalls. I have replaced the sparkplugs and the spark looks strong and bright and the check engine light is off. The engine runs smooth so I’m guessing compression is good. Any ideas? 

A. If this was being diagnosed in a shop, the next step or perhaps the first step would have been to check for engine codes and fuel trim reading. The next step would be to look at fuel pressure. In some cases, technicians will hook up a fuel gauge and mount it where they can see it. Then drive the car until it stumbles. With the ignition ON Engine OFF there should be 41.0 to 47.0 pounds of fuel pressure. With the engine running there should be 3-10 PSI less. When driving the car if the fuel pressure drops off considerably the issue could be a clogged fuel filter or weak fuel pump.

John Paul is AAA Northeast’s Car Doctor. He has over forty years’ experience and is an ASE-certified master technician. He will answer readers’ questions each week. Email your car questions to [email protected]. Follow John on Twitter @johnfpaul and friend him on Facebook, mrjohnfpaul.