acceleration problem 79 ford 250
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From: East Texas
acceleration problem 79 ford 250
I recently got a 79 ford 250 4x4. It is an automatic and i believe it has a 390. The truck will start immediatly with the turn of the key, but is real sluggish and has no power while going down the road. I have tried new plugs, distributor cap and rotor, coil, fuel filter, carb rebuild and still no change. The max speed I can get is 45mph. Any ideas on what may be wrong?
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Welcome to the site.
They stopped outting FE's in these truck in the mid 70's (76 I think) and the 3690 went in 4x4's.
I suggest you have a 351M or 400.
What was it like before you started buying parts ?
How many miles on engine/distributor ?
Possibly the Distributor is worn out or the vacuum advance seized.
How are the spark plug wires ? do a resistance test with a multi-meter.
Rule of thumb:
parts that turn or move wear out faster than electronics (unless you are operating in a hot climate)
They stopped outting FE's in these truck in the mid 70's (76 I think) and the 3690 went in 4x4's.
I suggest you have a 351M or 400.
What was it like before you started buying parts ?
How many miles on engine/distributor ?
Possibly the Distributor is worn out or the vacuum advance seized.
How are the spark plug wires ? do a resistance test with a multi-meter.
Rule of thumb:
parts that turn or move wear out faster than electronics (unless you are operating in a hot climate)
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From: In the Middle
At the top of the 73-79 forum there is a FAQ post with a lot of info about our trucks in it. Here is the link https://www.ford-trucks.com/forums/1...ease-read.html Scroll down to post #10 to read some tips on how to identify you engine.
Welcome to the forums!
Welcome to the forums!
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my '79 Bronco 4X4 with the 400 V-8 that i recently sold, went back and forth, sometimes it would run like a beast out of hell, and sometimes it would act like an inline 4 cylinder engine was under the hood. it was much better after the new carb and engine rebuild, but it still wasn't great, it accelerated decent, just not as good as it should of. That does sound wierd that the max speed in your F-250 is 45 MPH, sounds like a vacuum line is busted or it popped off. I had a '69 Mustang with a 302 V-8, and the tranny vaccum line got loose a few times, and it would only do about 50 MPH, but once the vacuum line was put back on and tight, it would hall butt and do as fast as 110 MPH.
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From: Sonoma, CA
When I got my truck it started really easily but did not have too much power. I checked the compression and it was acceptable. After checking the timing I found that the timing was set at 12 degrees retarded instead of advanced. Once I retimed it and rebuilt the carb it ran with alot more power. More like a 460 should.
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From: East Texas
Thank you for the replies. The truck ran very well before the parts. The truck belonged to my dad who always bragged about how much power it had. He got a new truck and gave this one to me. It has 150,000 miles on the original motor. We checked the vacuum lines and they are fine. It has dual exhaust with glass packs. I will try and check the timing and distributor this weekend.
Michael
Michael
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From: Northern Illinois
Originally Posted by N7ghtwolf
Does it have a cat on it?
Originally Posted by Allen095
It has dual exhaust with glass packs.
Originally Posted by Allen095
The truck will start immediatly with the turn of the key, but is real sluggish and has no power while going down the road. I have tried new plugs, distributor cap and rotor, coil, fuel filter, carb rebuild and still no change.
Originally Posted by Allen095
The truck ran very well before the parts.
I would also bet to say that it still has the OE plastic cam gear and you have jumped time. Pop off the dizzy cap and put a socket on the crank bolt and turn it back and forth, watch the dizzy rotor to see how much free play is in it.
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From: "Islander"
With a breaker bar and socket on crank you should be able to rotate crank back and forth and feel when the chain tightens up against the cam.
Half the total degrees slack is how retarded your cam is not counting the built in retard by the manufacture. A timing set replacement is a cheap repair.
Go thru dizzy and carb it will wake up unless compressions low and cam lobes are flat.
Half the total degrees slack is how retarded your cam is not counting the built in retard by the manufacture. A timing set replacement is a cheap repair.
Go thru dizzy and carb it will wake up unless compressions low and cam lobes are flat.
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