Doggie 460
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Cross-Country
Joined: Aug 2001
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Doggie 460
Well, not really a high performance question except it might be considered so. I have a 1988 Ford F450 dump bed truck with a 460 and manual 5 speed trans. The motor is several years newer than the old 1988 engine which died from overheating. The new motor has less than 40k miles on it and in my opinion has never run up to its power potential. The only mods I have done to it is to remove the venturi tubes in the air intake and advance the timing 2 degrees over stock. I also put a large free flowing motorhome muffler on it.
Anyway, the engine has always been low on power even though I know it is mechanically sound. I thought the cat converter might be clogged so I removed it. It wasn't clogged and as a matter of fact it was completely empty as the PO gutted the thing. So I put it back on the truck. I did replace the ignition control module and that helped to make it run more smoothly but no huge difference in power.
So now I am wondering if running it with the gutted cat might be messing up the engine controls? Everything concerning emission and engine controls is stock otherwise. Gas mileage is terrible at 9mpg but that is not too surprising I suppose. Thanks for any and all help.
Anyway, the engine has always been low on power even though I know it is mechanically sound. I thought the cat converter might be clogged so I removed it. It wasn't clogged and as a matter of fact it was completely empty as the PO gutted the thing. So I put it back on the truck. I did replace the ignition control module and that helped to make it run more smoothly but no huge difference in power.
So now I am wondering if running it with the gutted cat might be messing up the engine controls? Everything concerning emission and engine controls is stock otherwise. Gas mileage is terrible at 9mpg but that is not too surprising I suppose. Thanks for any and all help.
Cargo Master
Joined: Mar 2010
Posts: 3,342
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From: Laramie, WY
No worries on running without the cat. Your truck has no way of knowing if there's a catalyst or not. On an obdii truck, it will know the cats not working if it's missing, but that has zero effect on drivability.
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Joined: Aug 2003
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It probably doesn't apply here but there was a medium duty version of the 460 for dump trucks and school buses and such, the 7.0 or 429. You might can tell by the crank pulley.
460 has about 35psi at idle and 40psi when you goose it. Making power it should be near the high mark.
Fuel pressure, codes and timing would be a good start.
460 has about 35psi at idle and 40psi when you goose it. Making power it should be near the high mark.
Fuel pressure, codes and timing would be a good start.
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
A common cause of low pressure is weak fuel pumps; they can't keep up with the volume the injectors are using and so system pressure drops under load. However, start with a fuel filter, as a restriction there can cause the same issue. A bad pressure regulator can also open at too low of a pressure. OEM regulators are not adjustable, but even if they were, they won't create the pressure a failing pump fails to generate.
I always advise checking fuel pressure while driving. Too often the pumps can deliver what's needed while idling in the driveway (very short injector pulses) but cannot keep up with longer injector pulses needed in high load situations. The result is "it has good fuel pressure" but "still is low on power". Is it the pressure OK when the power is low?
Is this truck equipped with two fuel tanks? This era of truck has in tank "lift pumps" and one high pressure pump, correct?
I always advise checking fuel pressure while driving. Too often the pumps can deliver what's needed while idling in the driveway (very short injector pulses) but cannot keep up with longer injector pulses needed in high load situations. The result is "it has good fuel pressure" but "still is low on power". Is it the pressure OK when the power is low?
Is this truck equipped with two fuel tanks? This era of truck has in tank "lift pumps" and one high pressure pump, correct?
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