I have a 1991 Chrysler New Yorker with a 3.3 l engine, over 90K miles. It is getting very hard to start. It cranks a long time before the engine fires. I have replaced the fuel filter, checked fuel pressure(47lbs.) Does anyone have any ideas? Any help would be greatly appreciated. John
It is hard to start if it sets any length of time.
Probably because your fuel system is losing pressure as it sits, so the pump must refill and repressurize the entire system before the engine will start. This could mean the pump's output check valve has failed, or it could mean your fuel pressure regulator is faulty, or it could mean you have a small and undetected leak in the pressure supply side of your fuel system.
DS
Easy way to test that (pump losing pressure). Turn the key on, wait about
5 seconds, then try to start it. If it starts right up, the pump is losing pressure. If it doesn't, you may want to check your spark plugs.
The test you suggest will tell him nothing at all. The fuel pump runs for only a second or so on initial key turn-on, not enough to refill and repressurize a seriously drained system. It is a common myth that there is a pressure sensor and the pump runs until a particular pressure is reached. There is no such sensor.
A variant of your test that would come closer to revealing a fuel system drainback condition would be to turn the key to "on", listen for the fuel pump whirr to begin and to stop, turn the key "off", turn the key back "on", listen for the fuel pump whirr to begin and stop, turn the key "off", wait 45 seconds (induced prime will only occur twice within a
35-second period) , repeat, and *then* try to start the car. If it fires right up, the fuel system is losing pressure.If no fuel pump whirr on initial key-on, there's a problem with the fuel pump relay or its circuit, or there is an engine control module internal problem.
DS
I have the exact same problem in a '94 Ford Tempo (pressure falls off when not running). I have to turn the key on, listen for the pump to stop running, then it starts instant. Otherwise it sits and just cranks away.
I doubt that the entire fuel system from the injectors back to the tank are draining dry, it's just losing it's pressure, and letting the pump run before cranking the engine is an easy way to check that.
The other way is to hook a pressure gauge onto the fuel rail at the injectors and leave it there while it sits overnight. See what pressure the system has before attempting to start.
ok will try the test, if it is infact loosing pressure, is there a way to fix it without replacing fuel pump? Is the check valve on the fuel pump or somewhere on the outside of the tank? I really do appreciate all the help!
Thanks John
I'm sure there's a check valve made by someone, and a mechanic who will splice it into your fuel line just downstream of the pump. Is it a good idea? Who knows?
Built in.
DS
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