New engine giving problems
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New User
Joined: Jan 2003
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New engine giving problems
Hi everyone,
this is my first post so I will explain my situation first and then get to the specifics.
I have a 1986 f150 4.9L inline 6 4x2 carburated model that I recently put a new(well not new but different better engine) in but I have some problems I would like to ask you guys about.
So everything is hooked up except the thermactor system, I just plugged off the holes for now and disconnected the solenoids. I should mention that on the old engine the thermactor system was partially hooked up as far as vacuum lines and air hoses but I didn't have a belt on the air pump.
before I did all this work the engine ran ok except if you tried to give her gas she would just hesitate and give no power you had to be gentle with the accelerator to get her going, but she started everytime and idled well even after sitting for weeks in sub zero temps.
The new engine is in great shape, got good vacuum, zero oil leaks, and overall I thought it would perform better, but...
after starting in the cold even after sitting for just a day it idles really rough until she warm, when warm she settles in at around 750 rpm I would estimate. when cold it drops to 300 and then kicks up right before it is about to die then lopes right around 500 rpm.
Now when driving (this is going to be hard to explain in writing) it feels as though it is ok then it bogs for 5 seconds then it runs ok then bogs then ok and so on, and in any gear when not giving alot of gas( for example maintaing a speed of 30 mph in third) it feels jerky or like it is hesitating but if y0ou give her good gas you don't really feel the jerkiness just feel the on off bogging.
the only insight I have into this is that with the old engine after letting her sit for the winter I pulled her out started it and drove it to discover that It had the exact same bogging problem I am experiencing now, so I checked under the hood for som loose wires around the carb adn found that a mouse had chewed through two wires, the map sensor ground and ground for another four prong harness connection, which acording to teh wiring diagram goes to the carb dc meter so I re spliced the wires and presto the problem was gone.
but now all wires and connections look good and I still have this problem.
btw the four prong harness isn't hooked up now, but I can't remember if it was hooked up before because I turned my carb in for core exchange adn got a rebuilt one, would it be possible that the rebuilt one did not have the dc meter and I had to put it back on or was it possible that it was never hooked on the old one and that wire harness connection was just not used like some other connections?
sorry this is so long
thanks for any replies
Justin
this is my first post so I will explain my situation first and then get to the specifics.
I have a 1986 f150 4.9L inline 6 4x2 carburated model that I recently put a new(well not new but different better engine) in but I have some problems I would like to ask you guys about.
So everything is hooked up except the thermactor system, I just plugged off the holes for now and disconnected the solenoids. I should mention that on the old engine the thermactor system was partially hooked up as far as vacuum lines and air hoses but I didn't have a belt on the air pump.
before I did all this work the engine ran ok except if you tried to give her gas she would just hesitate and give no power you had to be gentle with the accelerator to get her going, but she started everytime and idled well even after sitting for weeks in sub zero temps.
The new engine is in great shape, got good vacuum, zero oil leaks, and overall I thought it would perform better, but...
after starting in the cold even after sitting for just a day it idles really rough until she warm, when warm she settles in at around 750 rpm I would estimate. when cold it drops to 300 and then kicks up right before it is about to die then lopes right around 500 rpm.
Now when driving (this is going to be hard to explain in writing) it feels as though it is ok then it bogs for 5 seconds then it runs ok then bogs then ok and so on, and in any gear when not giving alot of gas( for example maintaing a speed of 30 mph in third) it feels jerky or like it is hesitating but if y0ou give her good gas you don't really feel the jerkiness just feel the on off bogging.
the only insight I have into this is that with the old engine after letting her sit for the winter I pulled her out started it and drove it to discover that It had the exact same bogging problem I am experiencing now, so I checked under the hood for som loose wires around the carb adn found that a mouse had chewed through two wires, the map sensor ground and ground for another four prong harness connection, which acording to teh wiring diagram goes to the carb dc meter so I re spliced the wires and presto the problem was gone.
but now all wires and connections look good and I still have this problem.
btw the four prong harness isn't hooked up now, but I can't remember if it was hooked up before because I turned my carb in for core exchange adn got a rebuilt one, would it be possible that the rebuilt one did not have the dc meter and I had to put it back on or was it possible that it was never hooked on the old one and that wire harness connection was just not used like some other connections?
sorry this is so long
thanks for any replies
Justin
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
New engine giving problems
morecapitalizationandpunctuationwouldmakethatalote asiertoread
Apparently, you have the feedback carb, which is controlled by an EEC-IV computer. You should be able to pull the codes and find out what's happening. It sounds like an ignition fault (plug wires) because a fuel/air fault isn't usually so "instantaneous".
Apparently, you have the feedback carb, which is controlled by an EEC-IV computer. You should be able to pull the codes and find out what's happening. It sounds like an ignition fault (plug wires) because a fuel/air fault isn't usually so "instantaneous".
Thread Starter
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New User
Joined: Jan 2003
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New engine giving problems
thanks for the reply...
the problem was that I didn't hook up the carb dc meter on the rebuilt carb. so as I said in the "tranny going" post I went to the yard and found one, hooked it up and voila the engine ran ok, so I think the shuddering is the tranny, but then againg it may be the u0-joints as you suspected.
btw what's the cavil for?
the problem was that I didn't hook up the carb dc meter on the rebuilt carb. so as I said in the "tranny going" post I went to the yard and found one, hooked it up and voila the engine ran ok, so I think the shuddering is the tranny, but then againg it may be the u0-joints as you suspected.
btw what's the cavil for?
