1985 F-150 Stalling Problems
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1985 F-150 Stalling Problems
I have a 1985 F-150 4x4 with a 351 H.O. with the 4bbl holley. At about 1500 rpm it will stall out and fall flat on its face and most of the time it will die. But it will immediatley start right back off. If i let off when this does this and then give it throttle I can get past it or shift it into 2. This is an automatic c6 trans. I have replaced the inline filter on the frame and also the one on the carb itself. Air filter is good and it doesnt matter if the engine is cold or warm. I have also checked all vacumm leaks and found none. The engine has new plugs and cap and rotor about 2 months ago and I checked all of those and they seem in good condition. Also I had the trucks timing checked about 4 months ago but this prblem just arose about 3 weeks ago after my brother drove the truck and he doesnt have any clue what he did at all. He said he went over a bump and this started. Any Ideas??
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From: Niceville, FL.
Possibly a bad power valve (PV) in carburetor. A backfire through the carburetor is what usually causes PV failure but sometimes just age. To test: remove the primary float bowl, unscrew PV from main metering block, apply oral suction to threaded end of PV. If you get suction flow, PV is bad. There are numerous PVs that all look alike but operate at different vacuum levels. Make sure you get the proper one for your carburetor number to get best driveability and fuel economy.
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From: new jersey
stalling problem
Hey just my 2 cents,
Have you checked the vacume line to your trany module?? I had a simular problem w/ my 86 f150 351 2wd. it would get to a about 25mph and almost stall, until I would take my foot off the gas then it would come back to idle.
Trany fluid was being sucked through the trany vacume line from the module.
Again Just my 2 cents. Hope this helps
Al
Have you checked the vacume line to your trany module?? I had a simular problem w/ my 86 f150 351 2wd. it would get to a about 25mph and almost stall, until I would take my foot off the gas then it would come back to idle.
Trany fluid was being sucked through the trany vacume line from the module.
Again Just my 2 cents. Hope this helps
Al
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From: Edwards Air Force Base
Find a long hill or extended upgrade that will strain the motor a bit over a time period, say 2-3 minutes and see if you can make it up it. If it stalls out, I am betting you have a pin hole leak in the diaphram of your fuel pump. Happened to me years ago. Low RPMs and level ground I was OK, strain it by high RPM or climbing a hill and I was dead. It kept getting worse and worse until I figured it out.
Idea is the fuel pump works OKfor low load but when it really needs to work hard, it starts sucking air instead of fuel since the air is easier to move.
Just an idea, the above ideas from the others are good suggestions also.
Good Luck,
Lee
Idea is the fuel pump works OKfor low load but when it really needs to work hard, it starts sucking air instead of fuel since the air is easier to move.
Just an idea, the above ideas from the others are good suggestions also.
Good Luck,
Lee
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Well I tried a Coil Test and it passed with flying volts. I have an electric Fuel Pump on this carbed truck because it is a new motor and serp belt system. I checked all vacumm lines and no leaks there. It has started doing it all the time. Everytime I give it lots of fuel. If i ease into it it does not do it. If i get it into the secondaries it runs pretty good.
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From: new jersey
stalling
just another thought! could it be the sock in the tank? callapsing when accelerating? cause you said if you go easy it will go into it secondary's
Another 2cents worth.
Al
Another 2cents worth.
Al
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what do you mean by a sock in the tank? When I ease into the throttle it wont try to stall as bad and once I get it past the stalling part and punch it into the secondaries it runs pretty good. Is the powervalve only part of the primarys?
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From: new jersey
stalling prblem
The sock in the tank is another form of a fuel filter and if it callapses you would not get any fuel to the carburetor. the fuel pump vacume pressure, that sucks the fuel from the tank, on acceloration may be causing it to callaps. But Not sure if thats the case.
Let me ask you this, have you checked the fuel pump for pressure and volume.
you should have about 6-8lbs psi of pressure and on volume you should get about 1/2pint of fuel in 20 seconds. This is just food for thought. But you say the problem started after your brother hit a bump in the road? maybe the floats in the carburetor got wacked out
Al
Let me ask you this, have you checked the fuel pump for pressure and volume.
you should have about 6-8lbs psi of pressure and on volume you should get about 1/2pint of fuel in 20 seconds. This is just food for thought. But you say the problem started after your brother hit a bump in the road? maybe the floats in the carburetor got wacked out
Al
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When this problem started I replaced the fuel filter(s). I retested this and the problem did not go away. I did a fuel test and I filled 1 actual measuring cup to one cup in 15 seconds which means there is plenty of fuel. I checked the coil and that was fine. I replaced the cap and rotor and still did not fix the problem.
So the only thing I can think of that it is the carb.
So the only thing I can think of that it is the carb.
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well i took the sight screw off the side of the float bowl while the tuck was running and shoot the truck a little and it was right there at the bottom of the screw hole on both the primary and secondaries. The carb was rebuilt by a holly professional service mechanic about 1 1/2 years ago.
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From: Terre Haute, IN
plus you just don't want to rebuild hollies (I, personally, would much rather drive a daewoo then do that). Anywho, I have people come in all the time, and I had this same problem with my old '85. I had found that I had a combo problem. Not only did I need to re-tune the carb and dial it in, but I had a bad timing setup.
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From: new jersey
Stalling
Seth,
the float ajustment test is not to be done while the engine is running. Your suppose to run the engine to it's normal running temp, then turn the engine off, then remove the float bowl screw, if the fuel spills out then you must lower the level, if the fuel is below the the plug hole then you must raise the level. don't shake the truck. use a flash light to see fuel level. if the fuel level is at the bottom edge of the plug hole then you ok on the float adjustment.
Al
the float ajustment test is not to be done while the engine is running. Your suppose to run the engine to it's normal running temp, then turn the engine off, then remove the float bowl screw, if the fuel spills out then you must lower the level, if the fuel is below the the plug hole then you must raise the level. don't shake the truck. use a flash light to see fuel level. if the fuel level is at the bottom edge of the plug hole then you ok on the float adjustment.
Al
Last edited by gearshift101; Oct 25, 2006 at 05:12 PM.