| From | Message |
Aaron_T
Dodge Dakota
JOIN HERE
2/10/2004
08:07:32
|
 Subject: noise before startup
IP: Logged
Message:
I searched for similar reports of this noise but suprisingly did not find anything.
With my 2000 4.7L 4x4 Dakota not running, I turn the key to the accessory position and hear a noise from under the hood. It sounds like a pump running followed by a slight clunk: "vrrrrrrr... clunk". Not exceptionally loud but easy to hear. Total duration of the noise is about 1 to 2 seconds including the clunk.
Most of the time I turn the key from off to start the truck and the sound is lost by the actual sound of the engine starting. But when just turning to accessory I hear the noise every time. After it happens I can turn the key back to off, then turn it to accessory again and have the exact same noise.
I do not believe this indicates a problem as the truck has done this since I bought it a month ago and I have no other symptoms of problems. However I am curious as to what this noise is. Any ideas?
|
nwf_snake
Dodge Dakota
JOIN HERE
2/10/2004
08:50:32
| RE: noise before startup
IP: Logged
Message:
Electric Fuel Pump...
|
Aaron_T
Dodge Dakota
JOIN HERE
2/10/2004
16:44:46
| RE: noise before startup
IP: Logged
Message:
The next question would be... if it is the electric fuel pump, why does it make this sound on the Dakota? I've never heard this sound from any other vehicle, yet I'm sure they have had electric fuel pumps also. What is unique about the fuel pump/fuel delivery system in the Dakota?
|
Nope
Dodge Dakota
JOIN HERE
2/10/2004
18:49:27
| RE: noise before startup
IP: Logged
Message:
The fuel pump makes a distinct whine and can be quite easily heard coming from the back of the truck. Every car with fuel injection makes that noise.
What you are hearing is the actuators in the HVAC plenum. Try turning your HVAC fan to the off position. Do you leave it in defrost or directional heat all the time?
|
Aaron_T
Dodge Dakota
JOIN HERE
2/11/2004
08:07:57
| RE: noise before startup
IP: Logged
Message:
Yes, I do leave it on directional heat (Ohio in the winter, gotta love it). I will try switching it to off before turning the key and see if the noise is gone. I'll post back my findings.
The noise is much better explained by an HVAC actuator, thanks for the info!
|
Aaron_T
Dodge Dakota
JOIN HERE
2/12/2004
08:32:45
| RE: noise before startup
IP: Logged
Message:
I set the climate control dial to the OFF position (the blower was set to its lowest position too), turned the key to accessory... and the noise still occurred.
The sound is coming from the front of the truck but I cannot be more specific about the location. One of these days when it is warmer, I will have my wife turn the key while I listen under the hood.
Does anyone else with the 4.7L experience this sound???
|
Davy
Dodge Dakota
JOIN HERE
4/04/2004
14:17:42
| RE: noise before startup
IP: Logged
Message:
Aaron-T,
I get the EXACT same sound from my truck at startup. Sorry but I can't figure out what it is either. I have a 98 5.2L 4x4 automatic. I tried everything from turning AC on/off, door open/closed, keeping break depressed. Nothing seems to stop it. Doesn't seem to mess anything up, runs like a champ. Sound comes from front of truck (sounds closer to driver side). I was hoping someone on here would know what it was so I could laugh at how stupid I am for not knowing what it was.
|
slopehead
Dodge Dakota
JOIN HERE
4/04/2004
18:01:12
| RE: noise before startup
IP: Logged
Message:
when you turn the key to the "run" position the fuel pump turns on, thus the "rrrrr" the clunk comes from when the fuel injection system reaches full pressure and the pump shuts off. Have a Dak, 2 Concordes w 3.5, Intrepid w 2.7 and even a Sable that do it. also a Omni and a 3.0 Minivan that I no longer own either of did it. Others in my family report the same thing but only with fuel injected cars, running from Saturns all the way to Audi's, Mercedes, and even a Porsche.
|
WipLash
R/T
4/04/2004
18:30:57
| RE: noise before startup
IP: Logged
Message:
Same here.....
I've never really worried about. It would worry me if it didn't make that noise since all of them I’ve owned have made a similar noise. I wouldn't call the sound a clunk, but more of a click when the fuel pump reaches pressure and shuts off. I believe that loud "click" is the 12V solenoid on the fuel pump relay energizing and de-energizing when the fuel pump cycles on and off. I maybe wrong since I've never actually traced the noise down and documented it. I just assumed that was what the noise was since it sounds much like the solenoids I hear everyday in manufacturing engaging and disengaging.
It is one of the many relays somewhere in that large black plastic box located near the firewall/fenderwell.
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
