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HELP 460 ignition problems

Hi Everyone,

Sorry for the tag line but I am litterally at the end of my rope here.

I have a 460 from a 1988 F250, which has about 35K on a rebuild.

Let me start off by saying I use this truck about 5 times a year to tow my 26ft Pace Trailer and race car about 100 miles round trip.

The issues I am having are relating to stumbling and missing

The truck runs great when cold but once it warms up it is starts to mis and stumble when accelerating under load. The stumble is pretty bad - quite severe.

The following conditions are present:

-Idles very smooth and steady even when warm

-I have been chasing exhaust leaks since I got the truck and there are a few leaks (at manifolds) right now

-Cap, rotor and plug wires are all new

-Fuel pressure was very erratic (bounced between 25 and 45 PSI at idle) but this was fixed with a new filter

-Check engine light came on with a code of (lean) could be attributed to the leaks

I have now replaced the distributor and ignition control module and no change.

My next step is to carefully check all grounds and connections and clean, after that I am going to drive the truck off of a cliff.

Any ideas? Am I on the right track?

Anthony Calgary, AB

Reply to
anaphe
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One thing you didn't mention checking or replacing was the coil. A bad/weak coil can produce the symptoms you have described, especially after everything warms up.

RCE

Reply to
RCE

did you replace the spark plugs?

Reply to
samstone

Yep spark plugs are new.

I will look into the coil.

A
Reply to
anaphe

New coil made no difference. Any other ideas?

Reply to
anaphe

lean condition coud be several things, vacume leak, oxygen sensor,engine coolant sensor. id check all vac hoses first and try to get a scan with a better scanner. lucas

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Reply to
ds549

Exactly what do you think he's going to scan on an 88 F-250?

Reply to
aarcuda69062

because it runs ok cold , and the code comes up as lean- maybe a vacuum leak , even an intake/manifold gasket?

>
Reply to
samstone

Does it smell rich when warm? If so check the O2 sensor.

Al

Reply to
Big Al

88 means Carbereutor (bad spelling)... Check your float, sounds like a sticking float in the carb.. My dad had an 86 with the 460 and the holley 4bbl, did the same thing after a carb rebuild when the guy didnt set the float right.. sounds like the float is sticking in the carb and it needs cleaned..

Ford Tech

Reply to
Ford Tech

Sorry Ford Tech, you are wrong again. 1987 was the last year for the Carburetor on the Ford 460, and 1988 was the first year for the electronic fuel injection on the Ford 460. I will bet you $1000 on this point as I have one (1988 EFI 460) sitting in my tool shed right now, it is my farm truck. I can send you a picture if you like...

Reply to
My Name Is Nobody

Ok my bad. I thought 90 was the first year of the EFI 460...

Reply to
Ford Tech

were is the "ballast resistor" for the coil on that model? I had a Jeep J-20 had a similair sounding issue, turned out the ballast was in the wiring harness, nothing more than a resistor wire, and when she got hot the ignition went all kinds of screwey. I ran a new wire from the ignition switch to the coil and replased the coil with an MSD Blaster with internal ballast. Problem solved.

Whitelightning.

Reply to
Whitelightning

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