Hesitation on engine
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Hesitation on engine
I have a 91 302 engine in my 84 ford f-150. The engine has a bad hesitation problem and dies at stop signs when it is cold. When going from a dead stop the engine hesitates and wants to die. I think this is a carbeuration problem but im not sure. Is it a carb problem or something else?
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Joined: May 2004
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From: Edwards Air Force Base
Check your EGR valve. Dieing at stop signs is usually a sticking EGR valve.
They get a carbon buildup and then instead of closing like it is supposed to, it stays slightly open. I have had good luck in cleaning them and not replacing them but it all depends on how patient yet thorough you are.
Don't get too radical with it. Take it off, clean the metal parts inside with a brush and some solvent. Make sure and push it in and exercise it back and forth so it is smooth. DONT RIP or TEAR the rubber bladder or it is ruined. A little WD-40 and/or carb cleaner will melt that carbon and it should come right off after a while.
As much as it costs and fancy as it looks, it is just a spring loaded tapered rod that goes in a hole with a vacuum bladder to open it. When you are cruising along, it opens and lets exhuast fumes get sucked in to reburn. When you are at idle or rolling in to a stop sign and coasting, the vacuum drops letting the spring close the rod and letting the mixture go back to rich. If a carbon ring build up is there, it will stay partially open making the mixture too lean and the motor wants to die. When you go to accelerate, the mixture is also lean and also acts like a vacuum leak and thus it hesitates.
It could be something else but this is what I would bet on and it is cheap to do unles you have to buy a new one.
Be careful takking it off and you might be able to reuse the gasket. It is a foil and asbestos gasket and usually will seal back up OK as long as you don't rip it.
Good Luck,
Lee
They get a carbon buildup and then instead of closing like it is supposed to, it stays slightly open. I have had good luck in cleaning them and not replacing them but it all depends on how patient yet thorough you are.
Don't get too radical with it. Take it off, clean the metal parts inside with a brush and some solvent. Make sure and push it in and exercise it back and forth so it is smooth. DONT RIP or TEAR the rubber bladder or it is ruined. A little WD-40 and/or carb cleaner will melt that carbon and it should come right off after a while.
As much as it costs and fancy as it looks, it is just a spring loaded tapered rod that goes in a hole with a vacuum bladder to open it. When you are cruising along, it opens and lets exhuast fumes get sucked in to reburn. When you are at idle or rolling in to a stop sign and coasting, the vacuum drops letting the spring close the rod and letting the mixture go back to rich. If a carbon ring build up is there, it will stay partially open making the mixture too lean and the motor wants to die. When you go to accelerate, the mixture is also lean and also acts like a vacuum leak and thus it hesitates.
It could be something else but this is what I would bet on and it is cheap to do unles you have to buy a new one.
Be careful takking it off and you might be able to reuse the gasket. It is a foil and asbestos gasket and usually will seal back up OK as long as you don't rip it.
Good Luck,
Lee
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From: Virginia
If the egr checks out, then take the aircleaner off, and with the engine off, look down the carb and push the throttle back. You should have two strong streams of gas pouring into the engine. If you don't, or they are weak dribbles, then the accelerator pump is bad.
When you do the test above on a overnight cold engine, you should have to pull the choke door open to see down in the carb after you hit the accelerator. If the choke door is not closed, then the choke is not working correctly and that will make the engine take longer to warm up and stall when it's cold.
When you do the test above on a overnight cold engine, you should have to pull the choke door open to see down in the carb after you hit the accelerator. If the choke door is not closed, then the choke is not working correctly and that will make the engine take longer to warm up and stall when it's cold.
