'92 WT 1500 4.3L 65,000 Miles Suddenly Slow to Start, Cranks a Lot
I use the truck pretty much only as a truck. So, it sits between loads of whatever. It
has always started right up. (Note: Just replaced fuel filter since it was due anyway.
Problem started before I replaced fuel filter.) Suddenly it takes many seconds to start.
Guess I should check fuel pressure maybe? I can't hear the system
priming/pressurizing when I turn on the key. Should I? Honestly, I can't say if I ever
heard it previously. How long should it prime/pressurize if it does? A couple of
seconds? What could this be other than the fuel system since it's a sudden onset
thing and once it starts it runs just fine?
I have a 95" Silverado, and when I start it I noticed the electric fuel pump running. I always just start it, not waiting for the pump build to pressure. It takes about 5 sec. for mine to turn off without starting the truck. You should have about 20 LBS pressure min. if you check it. I believe it needs 17 LBS to run. I have 90 LBS on mine, but my motor is modified. The thing that dose make a big difference is the distributor cap & rotor. The terminals at each post get corroded for lack of words, adding resistance to the spark. You can clean these off along with the rotor tip, to see if this helps your problem. If so, replace with new. Spark plugs are another factor. Check them for build up and wear. Make sure to set the gap if putting in new. Chevy trucks tell you what to set them at under the hood.
More info. From what I've gathered, it appears as though even if the fuel pump relay is faulty, after cranking enough the oil pressure switch energizes the fuel pump through an alternate pathway so that can keep the vehicle running. So, I bench tested the fuel pump relay . . . and it appeared fine! Next, I reinstalled it and had someone else turn the key while I stayed outside listening. The fuel pump *did* come on to pressurize the system . . . but not always. Dang! So, I decided I had to observe the fuel pump relay activating while *not* hearing the fuel pump pre-pressurizing before cranking. Eventually I did observe this behavior so it seems like I've either got a failing fuel pump or faulty wiring from the fuel pump relay back to the fuel pump. Argh! Nothing is easy.
I need to correct myself, fuel pressure should be at 60lbs. on the line going into the engine bay (min). OK then there should be a plugin on top of the gas tank that goes to the sending unit and fuel pump, you can check for power there, but I'm thinking the fuel pump. If you go that far, you have to drop the gas tank, or lift the box off to get at it. So you might as well replace the sending unit while you are there. I paid someone to do this, a garage, they charged 3 hours labor so you have an idea. There is no extra charge putting in a new sending unit because it has to come out anyway to get to the fuel pump.
I've got to spend a bit more time troubleshooting so I really know what's going on (and what's NOT going on) and when. Then I'll dig in. This is my spare truck so I'll probably go down to my buddies shop and do the fuel pump and sending unit on my own eventually. Thanks. Not sure if I'll pull the bed or drop the tank. Half a dozen of one and six of the other kind of situation? I know of one guy who chopped a hole in his bed. If I knew exactly where to cut that might be a viable option since I have a liner and the bed is like new. Easy patch job.
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