Motor Pinging...
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Senior User
Joined: May 2002
Posts: 217
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From: Virginia
Motor Pinging...
Valve covers were leaking pretty good. So I pull the upper intake off, take the throttle body off and clean it real well, replace the valve covers, new manifold gasket, put it all back together, and clean the motor with some Gunk.
Now the motor is pinging under a load. And pretty bad. Only when it warms up though.
I didn't move the distributor. All the plug wires went back on where they came off. The upper is torque to specs. And I can't find a vacuum leak anywhere.
So where/what should I check next??
It almost seems to me that it's not physically getting enough gas. Could this just be a coincedental fuel pump failure or fuel pressure regulator failure? The vacuum line is attached...
I did find a dent in the right side fuel rail. But it was there when I pulled the upper off. So if it's been dented for a while, why is it acting up now?
And to top it all off, my IAC motor is screwing up and the truck won't idle less than 2000 rpm...
Ideas? Suggestions?
Now the motor is pinging under a load. And pretty bad. Only when it warms up though.
I didn't move the distributor. All the plug wires went back on where they came off. The upper is torque to specs. And I can't find a vacuum leak anywhere.
So where/what should I check next??
It almost seems to me that it's not physically getting enough gas. Could this just be a coincedental fuel pump failure or fuel pressure regulator failure? The vacuum line is attached...
I did find a dent in the right side fuel rail. But it was there when I pulled the upper off. So if it's been dented for a while, why is it acting up now?
And to top it all off, my IAC motor is screwing up and the truck won't idle less than 2000 rpm...
Ideas? Suggestions?
New User
Joined: Jul 2003
Posts: 5
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Motor Pinging...
i have a similar problem ,but its when i accelerate and take the rpm over 4 the engine starts shaking and i hear a knocking sound and when i drive it while its doing that the car doesnt have any power like if i didnt have enough fuel going in its like chocking any ideals???? at first i thought the motor was the problem so i changed the engine and its still doing that so i figure its something that was already in the car like fuel pump or injectors cause i took my old intake and injectors and put it on the new motor ,so any kind of help would be appreciated!! oh and the distributur is the same one i had on the other motor too and when i drive the car slowly and dont take the rpm pass 3 it runs fine !!!
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Senior User
Joined: May 2002
Posts: 217
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From: Virginia
Motor Pinging...
I checked the TPS and it was at .49 volt. So I fixed that and my idle problem is gone. But it still gets a spark knock under load.
I'm gonna find a good timing light and check that next.
I'm gonna find a good timing light and check that next.
Elder User
Joined: Jan 2003
Posts: 539
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Motor Pinging...
Fuel pressure regulator, check that first. get a fuel pressure guage and hook it up to the shraeder valve on the fuel rail.
You should have around 50 -psi with key on and engine off.
If you have that, start engine and look again. should be 8-10 psi lower, Optimum psi running is 41-44 psi. If you do not have the right pressure (low) more than likely you have a weak fuel pump.
Pull the vacuum line off of the regulator and see what the pressure is now, should be higher. Plug the vac line and take a drive. Better now? You could just need a new fuel filter also. A plugged fuel filter can cause the symtoms you both describe.
If the pressure is high (above 60) you need a new regulator.
Sounds as though you have a weak fuel pump.
Good luck.
You should have around 50 -psi with key on and engine off.
If you have that, start engine and look again. should be 8-10 psi lower, Optimum psi running is 41-44 psi. If you do not have the right pressure (low) more than likely you have a weak fuel pump.
Pull the vacuum line off of the regulator and see what the pressure is now, should be higher. Plug the vac line and take a drive. Better now? You could just need a new fuel filter also. A plugged fuel filter can cause the symtoms you both describe.
If the pressure is high (above 60) you need a new regulator.
Sounds as though you have a weak fuel pump.
Good luck.
Last edited by fishin1976; Aug 27, 2003 at 02:40 PM.
Elder User
Joined: Oct 2002
Posts: 861
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From: Marysville Wa
Motor Pinging...
my motor swap with my 351 has had a slightly off idle with what feels like it is sluggish and possibly underpowerd (when you take off it feels like it has a time delay) i checked the press and it said 35 at idle with the vaccume connected, the fuel filter has been changed, timing set plugs, plug wires, coil have all been changed, O2 has been changed, do you think its bad fuel press?
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Senior User
Joined: May 2002
Posts: 217
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From: Virginia
Motor Pinging...
Well I checked the timing and it was just a hair under 10* btdc. So I didn't mess with it. I also put a new cap, rotor, plugs and wires on. It helped a little with low end responsivness, but it's still pinging.
A friend has a fuel pressure tester, but he didn't have the right size schrader valve adapter for me. So I gotta find one of them.
But I'm pretty sure that's gonna be the problem. He used to work at a Ford/Dodge dealer about 8 years ago. He worked on the Dodge side, but he said he remembered seeing a lot of F series trucks coming in with bad fuel pumps.
So we'll see...
A friend has a fuel pressure tester, but he didn't have the right size schrader valve adapter for me. So I gotta find one of them.
But I'm pretty sure that's gonna be the problem. He used to work at a Ford/Dodge dealer about 8 years ago. He worked on the Dodge side, but he said he remembered seeing a lot of F series trucks coming in with bad fuel pumps.
So we'll see...
