stumbles at 160 degrees
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
stumbles at 160 degrees
i have a question here because this is the greatest headscratcher for me ever. i know my carb is 100% dialed in so that cant be the issue, please dont dwell on that with all due respect. i have swapped jets and spent so many sleepness nights wrenching on this thing to get it running the perfect mixture that it is.
the truck runs like a champ hot, and it runs like a champ cold. but it does not like to run luke warm. when sitting in the driveway waiting for it to warm up everything is going fine up until juuuust before the thermostat opens, then she puts up a huge fight and stubles. doesnt load up or anything, just runs real rough and puts up a fight. then when the coolant starts flowing it runs like a raped date. i love my truck and i've spent alot of time and money working on it, everything is real tight and dialed in. the one and only thing thats lingering in my mind is it could be the water pump. maybe the bearings or whatnot are going out and it doesnt like the pressure that the cooling system builds up? around 13 psi i believe....
thanks guys
also can someone please tell me what the fuel pressure is from my stock fuel pump? not that i think this is related i just am wondering
the truck runs like a champ hot, and it runs like a champ cold. but it does not like to run luke warm. when sitting in the driveway waiting for it to warm up everything is going fine up until juuuust before the thermostat opens, then she puts up a huge fight and stubles. doesnt load up or anything, just runs real rough and puts up a fight. then when the coolant starts flowing it runs like a raped date. i love my truck and i've spent alot of time and money working on it, everything is real tight and dialed in. the one and only thing thats lingering in my mind is it could be the water pump. maybe the bearings or whatnot are going out and it doesnt like the pressure that the cooling system builds up? around 13 psi i believe....
thanks guys
also can someone please tell me what the fuel pressure is from my stock fuel pump? not that i think this is related i just am wondering
Last edited by Danger_Dave; Feb 12, 2008 at 01:12 PM.
Elder User
Joined: Feb 2005
Posts: 526
Likes: 1
From: Spokane, WA
That sounds like a simple choke timing problem. The choke is either coming off too fast or too slow. Does the heater hose line go by the choke thermostat? If so I would venture to guess it is coming off too slow and the hot water helps it open quicker once the thermostat opens.
This is assuming you are using a choke thermostat and not a manual choke.
Depending on where you live and the weather, it could be icing up the throttle plates (my V8 Courier did it every year). This is easy to check, start the vehicle with no air cleaner and watch down the throat. If it is icing up, you will see the plates turn white, once the engine is warm it will go away. Wouldn't happen to be running a Holley would you? Icing is usually at its worst just above freezing in damp conditions.
Yeah, I know...no carb stuff...but where else can it be? Timing...no, fuel pressure...no, head gasket...no...if it ran good before and you are having issues now it is something you have done.
Good luck!
Kenny
This is assuming you are using a choke thermostat and not a manual choke.
Depending on where you live and the weather, it could be icing up the throttle plates (my V8 Courier did it every year). This is easy to check, start the vehicle with no air cleaner and watch down the throat. If it is icing up, you will see the plates turn white, once the engine is warm it will go away. Wouldn't happen to be running a Holley would you? Icing is usually at its worst just above freezing in damp conditions.
Yeah, I know...no carb stuff...but where else can it be? Timing...no, fuel pressure...no, head gasket...no...if it ran good before and you are having issues now it is something you have done.
Good luck!
Kenny
Thread Starter
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
the choke is manual. i push the **** back in after about 20 seconds when its capable of combusting a normal mixture. icing is not the issue. its about 40 here in the morning. but she sits in my garage nice and warm and dry. heater hoses just go off the water pump back into the intake.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
I guess you could try it with the belt off and see how it acts at the magic temp . If it goes away, it could be a pump, but you would think the belt would slip first.
Also monitor the alternator voltage to make sure it isn't dropping off causing a weak spark.
Also monitor the alternator voltage to make sure it isn't dropping off causing a weak spark.
Last edited by LxMan1; Feb 12, 2008 at 09:06 PM.
Posting Guru
Joined: Mar 2005
Posts: 2,068
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From: western montana
i'm wondering how you dialed the carb in... using a o2 sensor or...
Not to question whther it's dialed in but i need to do that NOW and am interested in the process you used.
I have no useful input...except that it pretty much seems to be either the pump or spark .... or vacuum if you have any of the temp actuated valves.
Please make sure you update when you get it right.
Not to question whther it's dialed in but i need to do that NOW and am interested in the process you used.
I have no useful input...except that it pretty much seems to be either the pump or spark .... or vacuum if you have any of the temp actuated valves.
Please make sure you update when you get it right.
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