, Salem, MA

October 5, 2013

Auto Scanner: Recurring problems starting pickup truck

Auto Scanner
Larry Rubenstein

---- — Q: I have a 1997 Chevy K1500 Pickup 350 CID. I have used starting fluid to start it every morning, and now when I leave work. It runs great after it starts. I don’t want to give up on it; it’s a good truck.

A: It sounds like your truck is losing its fuel pressure when it is parked for an extended period of time. The most common cause is the fuel pressure regulator. The regulator’s job is to maintain the fuel pressure that the truck needs and send the rest back to the fuel tank. The way to test this is to put a fuel pressure gauge on the fuel pump rail. Run the truck to build proper fuel pressure. Turn the truck off and watch the fuel pressure gauge. If the gauge drops down, you definitely have a leak. Block off the return, and if the pressure stays, you know you have a bad regulator. If the pressure still drops, it is most likely a leaking fuel injector.

Q: I have a 1999 Lexus RX300 that is having problems. Here are the symptoms: check engine lights (on here and there, sometimes off for weeks after I clear them, then back on again). Codes: P0300, P0302, P0304, P0306, P0171. Also, on the highway, the car starts to buck/hesitate when keeping the speed constant. To remedy this, I either take my foot off the gas or accelerate. This also happened and the engine light flashed as opposed to just lighting up. After this, the code was only P0171, and I can’t seem to clear it. It seems like it happens when the gas tank gets to half or lower, then it goes away when I fill up, although this could be my imagination. Do these symptoms ring a bell?

A: All the codes you list indicate both a lean condition and a misfire. I think you may be on to something when you say the problem happens when the tank is less than half full and goes away when filled up. My thought process goes to a problem that Chrysler had many years ago with the fuel tank pickup tube. These tubes would develop a hole halfway up. When the tank dropped under a half, the fuel system would push air and fuel mix rather than the straight fuel mix. When the tank level was higher than the hole, it would push fuel only, although at a lower pressure. Sounds like an interesting job. It could get expensive, but diagnostics need to be done to be sure.

Car Care Tip: When preparing your emergency winter-driving kit for the trunk of your car, do not forget a blanket and a can of WD-40, along with your usual supplies. It is also a good idea to throw a pack or two of sealed peanut butter crackers in your glove compartment.

