EEC Problems. Can anyone PLEASE help?
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EEC Problems. Can anyone PLEASE help?
I have a 1991 F-350 XLT lariat Crew cab 4x4 with a 7.5L 5-sp manual and 4:10 gears. The truck came with a E40D transmission but died. So I traded it out with the manaul. I also had a fuel pump that wouldnt turn off, so was led to change the EEC. I did, but from a 1989 with the same comfiguration.
Heres my problem: The truck has the power that you would expect from a 460 in 1st, 2nd, and 3rd gears. When you go to 4 or 5 gears the truck starts fibrating, bucking and obviously lacking in alot of power.
Now a new computer for the exact truck comes up with 3 different numbers, but does not specify what changes the computer.
Does anybody know what either narrows the number down to specific to my truck, or can anybody give me the number on their exact same truck?
Thanks Logan
Heres my problem: The truck has the power that you would expect from a 460 in 1st, 2nd, and 3rd gears. When you go to 4 or 5 gears the truck starts fibrating, bucking and obviously lacking in alot of power.
Now a new computer for the exact truck comes up with 3 different numbers, but does not specify what changes the computer.
Does anybody know what either narrows the number down to specific to my truck, or can anybody give me the number on their exact same truck?
Thanks Logan
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Yeah but the truck would have a million of them. For when I bought the truck he had black tape over the "check engine" light. So I am not certain that would show me what is wrong now. Maybe I am wrong. I did also notice that he had eliminated the "cat" and dead ended a couple of components for the emissions.
Thanks Logan
Thanks Logan
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
Any computer that will run a truck with a 460 will run your truck. You could even use one from a different year and be fine.
I think you should assume that the computer you have is good until you can come up with a good reason otherwise, and treat this as an engine problem. In order for the computer to run things correctly right most of the emissions stuff has to be there and working. You can get away with getting rid of the cats and the air pump and some of the plumbing, but stuff like the EGR has to be connected and working if you have any hopes of making the engine run right.
Also check the fuel pressure, timing and vacuum when you get a chance. These tests, along with the codes from the computer, will point you in the right direction when fixing all the things it sounds like the PO did to it.
I think you should assume that the computer you have is good until you can come up with a good reason otherwise, and treat this as an engine problem. In order for the computer to run things correctly right most of the emissions stuff has to be there and working. You can get away with getting rid of the cats and the air pump and some of the plumbing, but stuff like the EGR has to be connected and working if you have any hopes of making the engine run right.
Also check the fuel pressure, timing and vacuum when you get a chance. These tests, along with the codes from the computer, will point you in the right direction when fixing all the things it sounds like the PO did to it.
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Well that's not encouraging and lets hope the previous owner didn't butcher the wiring harness but there is no other way around this, all these computers work the same and will throw the same codes when they don't get the correct inputs, so replacing it again won't fix anything. You have a bit of a mismatched system now but for the most part everything connects to the computer on the same pins so reading the codes will help narrow down the problem. There may be a lot of codes but many of them can be ignored if you get one or 2 that show a serious problem, focus on those and fix the problem, clear the codes and start over.
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Thanks guys
well thanks guys. I guess I will go and get some codes off it, and run through that. I think you might have saved me a few hundred bucks. I will post back with more codes and problems.
Thanks Logan
Thanks Logan
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1991 fords have high pressure fuel pumps in the tanks.
1989 fords have low pressure fuel pumps in the tanks and a secondary high pressure pump.
These are electrical pumps controlled by the EEC via the fp relay. I don't know how the the 7.5 motor EEC handles the two pump situation.
1989 fords have low pressure fuel pumps in the tanks and a secondary high pressure pump.
These are electrical pumps controlled by the EEC via the fp relay. I don't know how the the 7.5 motor EEC handles the two pump situation.
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thanks
So you think that the computer might be wrong because the pumps are different? I have talked to people from performance shops as well that tell me that only 1991 EEC will work for 1991 truck. So I have got so many different ideas but none of them helps me if I don't know for sure.
I am lost.
I am lost.
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Post Fiend
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From: Bonita Springs FL
So you think that the computer might be wrong because the pumps are different? I have talked to people from performance shops as well that tell me that only 1991 EEC will work for 1991 truck. So I have got so many different ideas but none of them helps me if I don't know for sure.
I am lost.
I am lost.
FTE Legend
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From: Ottawa, Ontario
The pumps are all powered through the pump relay.. doesn't matter what year it is as far as that goes. There could now be a fuel pressure problem so you should check it both at idle and while driving just to see if the pressure is dropping at higher speed. If it doesn't then you can eliminate fueling as the probable cause.
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Sorry for wasting everybodies time. I am a complete idiot. I took the persons word that I bought the truck from that the engine was rebuilt. Then I sunk about 150 hours and tons of money into the transmission and the rest of the truck. Only to at the end of it all take a compression test to find that the motor is sacked!!!
NOT HAPPY
Thanks Logan
NOT HAPPY
Thanks Logan
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