HELP 1988 Ford F-250 460EFI burning way too rich - 460 Ford Forum
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post #1 of 12 (permalink) Old 01-10-2011, 07:56 PM Thread Starter
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HELP 1988 Ford F-250 460EFI burning way too rich

I need some help on my 88 F-250 Ford 460 with EFI. I recently brought it in because it wouldn't start after someone left the key on in it. The computer was fried so he put a new computer in. When I picked it up it topped out at 30, barely made it up small hills, ran really rough and was puffing black smoke the whole way. It took almost 5 gallons and the drive was only 7 miles. Every once in a while it would start running right but when you would hit a bump it would go back to burning really rich. I don't know what is wrong so I figured I would ask you guys for some ideas on what might be wrong. Thankyou
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post #2 of 12 (permalink) Old 01-10-2011, 08:59 PM
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running rich efi 460

things to check check for

vacuume leaks on intake. get a pressure guage and see how much you have 17-22 is the norm for a stock engine. and if its steady or fluxing all over. make sure there is no cracked lines.


map sensor (if its bad the truck will run bad or not at all)

oxygen sensor

air intake sensor (on intake close to the distrubitor)

coolant temp sensor (on intake as well towar the back driver side)

TFI moduel those can be checked at the local autoparts store

possible not likely IAC ( idle air control valve) can affect it while cold but not so much when the the engine is hot.

either way the eec is getting a bad signal from above or massive vaccume leaks. which tells the eec to lengthen the injector duty cycle. hope this helps.
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post #3 of 12 (permalink) Old 01-10-2011, 09:56 PM
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fuel preasure regulator could be bad - pull vaccum line off when running and see if gas comes out of reg.
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post #4 of 12 (permalink) Old 01-11-2011, 10:13 AM
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I would check TFI module and fuel pressure regulator as they seem most likely. I would swap the TFI with a known good one as I went through similar issue with an 86 F150 last year and the module tested fine so I put a new computer in it and still did the same thing, got mad after spending the money on a new computer and pulled a TFI off a spare distributor I had and solved the problem.

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post #5 of 12 (permalink) Old 01-11-2011, 10:24 AM
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My vote is for the map sensor and check the fuel pressure.
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post #6 of 12 (permalink) Old 04-09-2011, 11:01 PM Thread Starter
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where is the fuel pressure regulator?
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post #7 of 12 (permalink) Old 04-10-2011, 01:18 AM
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Quote:
Originally Posted by lowranger View Post
My vote is for the map sensor and check the fuel pressure.
X2, or the E.C.T. Sensor is bad (engine coolant temp) stuck to the cold side.

557ci 70 Maverick, 8.76@153 1.25 60ft.... So far....
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post #8 of 12 (permalink) Old 04-10-2011, 11:22 AM Thread Starter
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I replaced the MAP sensor and that didn't help at all. Should I try the fuel pressure regulator next?
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post #9 of 12 (permalink) Old 04-10-2011, 11:36 PM
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Pull the vacuum line off of it when the engine is running, and see if there is fuel coming out of it.

557ci 70 Maverick, 8.76@153 1.25 60ft.... So far....
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post #10 of 12 (permalink) Old 04-11-2011, 03:51 PM
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What about PIP(profile ignition pickup)? I think it's otherwise known as the pickup coil by most people. When I get issues like this I do diagnostics the hard way because I do not have a scan tool.
#1- I check for proper charging system voltage at the battery
#2- I check the engine vacuum, compression, and general engine condition.
#3- I check the power and ground supplies to the ECM
#4- I check EVERY SINGLE ECM input at the ECM AND at the sensor(tps, iac, egr, o2, map, ect, etc.). This method also checks the wiring between the sensors and ecm if you compare the readings at the ecm to the readings at the sensors. I also determine whether the sensors are bad OR reporting incorrectly because the mechanical element they are measuring is messed up.
The ECM is considered faulty after all of the above has been tested and found to be good.

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post #11 of 12 (permalink) Old 04-11-2011, 04:15 PM
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Most likely ECT or pressure regulator.

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post #12 of 12 (permalink) Old 04-11-2011, 07:15 PM
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Possibly the wrong ECM (possibly misslabled if a flashed one
) or a bad one. Worst fuel issues are most likely a bad thermostat.
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