460 fuel injection problem
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460 fuel injection problem
Hi to the group. We own a 1990 Rexhall motor home with an EFI 460 engine. It has run like a top for years. Last fall it began to backfire like crazy when you took your foot off the pedal. Fuel mileage went in the toilet, it was pouring fuel through the engine. I suspected water in the fuel since the generator, which feeds from the main gas tank, wouldn't start. A mechanic worked on the vacuum system which was leaking and we added all kinds of fuel conditioner to eat water. Barely got home and parked it for the winter. This spring I took it in for an ignition tune which did nothing. It died 3 times on the way home, finally rolling into the yard and dying again. I would suspect the famous Ford fuel pump problem but why is it flooding the engine with fuel? Must be a sensor or computer issue. Any ideas where I can start? Local mechanics are helpless if the computer can't tell them what to do. Ford dealer won't look at me because it is a motorhome.
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So some posts on another forum suggest looking at the fuel pressure regulator. If the diaphragm is breached the vacuum will pull more fuel into the engine. Anybody know where I can get a good parts breakdown for this engine on the web?
Laughing Gas
Joined: Mar 2011
Posts: 811
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From: West Central Southern MN
I would guess your IAB(idle air bypass) valve is faulty. When your throttle body closes, the IAB is supposed to open and let a regulate amount of air through. This may be the cause of the backfire. You need to check the PCM for codes. Most small town mechanics will check them for free if you are nice and willing to work with them. I check my codes with this;
http://m.summitracing.com/parts/ino-...ZOYaApUb8P8HAQ
There are going to be differences between yours and an f-series motor. I usually just look up the parts diagrams on rock auto even though they are not the best.
http://m.summitracing.com/parts/ino-...ZOYaApUb8P8HAQ
There are going to be differences between yours and an f-series motor. I usually just look up the parts diagrams on rock auto even though they are not the best.
Laughing Gas
Joined: Mar 2011
Posts: 811
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From: West Central Southern MN
Originally Posted by Skygeezer
So some posts on another forum suggest looking at the fuel pressure regulator. If the diaphragm is breached the vacuum will pull more fuel into the engine. Anybody know where I can get a good parts breakdown for this engine on the web?
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So I replaced the fuel pressure regulator and the IAC valve. The engine starts and idles but is very rough. I bought an OBD I Ford code reader. With the engine off ( KOEO test ) I got a code 67 on the self test and codes 33 and 87 on the continuous ( memory ) readout. However when I tried to do the engine running (KOER) test the code reader did nothing, just sat displaying zeros and didn't even try to run a test. I followed the manual for the sequence of the test and warmed up the engine. Tried holding the test key down for 10 seconds, turning the code reader on and off etc. Called Innova and they said the OBD I systems are variable and unreliable. They couldn't tell me why the reader would do one test and not the other, but say they run into this on occasion with older vehicles. So, no joy on this problem yet. Guess I will look for an old mechanic somewhere who knows the engine.
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