Rough idle
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Rough idle
Hi guys. I have an 83 F250 with a 7.5l. I recently had a problem with my fuel pump that I fixed. Now my truck is idling really rough. Stays around 600 rpm and smokes. The smoke is white but it leaves black sut on the ground. When I drive it down the road it runs great but will back fire occasionally when I push in the clutch. Any ideas why it's running rough?
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Freshman User
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It smokes all the time though and it's not running smoothly. It almost feels and acts as if it has a cam in it. Even if I increase the idle it still runs choppy with smoke
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
Despite the water problem, you say you had a fuel pump problem that you "fixed" but now it runs like crap... nobody can read your mind and we have no idea exactly what you are talking about... what did you do to fix it? Can you un-fix it and see if it runs better?
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
I agree with Chris - white smoke means you have a head gasket leak. You'd better check the coolant level, and run some tests. The best is a leak-down test, which will tell you that you have a leak and where. But, the parts stores should have a strip that you can dip in the radiator and it will tell if you have a head gasket leak.
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pedant
Joined: Jan 2008
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From: EXTREME southwest CT
The parts stores "rent" a cooling system pressure tester that replaces your radiator cap and allows you to find a leak by removing the spark plugs and seeing which cylinder fills with coolant.
It's not too uncommon for 460's to get a crack between the spark plug and exhaust valve seat (I've done it TWICE)
It's not too uncommon for 460's to get a crack between the spark plug and exhaust valve seat (I've done it TWICE)
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pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
When you say "backfire", is it actually blowing back through the carb or is it popping off in the exhaust?
I ask because IME this will point to either a blown power valve or a sloppy timing chain.
I ask because IME this will point to either a blown power valve or a sloppy timing chain.
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It is popping off in the exhaust.
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Joined: Nov 2007
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From: Denver Metro Area, CO
If you make a change, and suddenly something is broken, the most likely cause of that breakage is your change, so change it back to how it was and see if the problem goes away.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
If you make a change, and suddenly something is broken, the most likely cause of that breakage is your change, so change it back to how it was and see if the problem goes away.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
Thread Starter
|
Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
If you make a change, and suddenly something is broken, the most likely cause of that breakage is your change, so change it back to how it was and see if the problem goes away.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
Reading another thread of yours, it seems you have jerry-rigged the fuel pump to be powered from the from the defroster-motor circuit.
The blower/defroster motor generally operates on low/medium/high speeds... which makes me wonder if you're feeding full voltage to your fuel pump and if your engine misbehaving isn't because of low fuel pressure or some other electrical anomaly you have introduced into the system via such a jerry-rigged configuration.
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
Man, you really need to be clear in what you're trying to describe...
In your first post, you tell us you fixed the fuel pump and now you have a rough idle, leading us to believe one event caused one reaction; you are now telling us you already had a rough idle before rigging the fuel pump and we should ignore your initial description?
In which case, chase the water entering your combustion chambers, water doesn't burn. A leak-down test will reveal worlds of stuff....
In your first post, you tell us you fixed the fuel pump and now you have a rough idle, leading us to believe one event caused one reaction; you are now telling us you already had a rough idle before rigging the fuel pump and we should ignore your initial description?
In which case, chase the water entering your combustion chambers, water doesn't burn. A leak-down test will reveal worlds of stuff....
Thread Starter
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Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
Man, you really need to be clear in what you're trying to describe...
In your first post, you tell us you fixed the fuel pump and now you have a rough idle, leading us to believe one event caused one reaction; you are now telling us you already had a rough idle before rigging the fuel pump and we should ignore your initial description?
In which case, chase the water entering your combustion chambers, water doesn't burn. A leak-down test will reveal worlds of stuff....
In your first post, you tell us you fixed the fuel pump and now you have a rough idle, leading us to believe one event caused one reaction; you are now telling us you already had a rough idle before rigging the fuel pump and we should ignore your initial description?
In which case, chase the water entering your combustion chambers, water doesn't burn. A leak-down test will reveal worlds of stuff....