1990 360 TBI strange problem
 

We have a 1990 D350 Dump "gifted" to us for $300. No rust on body/dump/frame. Came with the wheels for the left rear in the bed, 8 damaged wheel studs and 1 broken left rear spring hanger plate. $234.80 and a few hrs fixed that and now-
The 360 is running so rich on fuel it smokes and has no power. We have found in our shop that-
The emissions light is not on
Turning the key on and off in sequence per repair manual does not produce any codes
Our Snap on Modus scanner will plug in the adl port but says it "cannot communicate with vehicle, incorrect data stream"
There is 12v power into the computer(at the plug)
The computer is running the ign just fine, as in it advances the timing as rpm goes up and varies it around with load.
replacing the egr valve had no effect, air filter, fuel filter, cap/rotor/wires/spark plugs had very little effect. All fuses/relays test good. grounds are clean.
The TBI is pulsing the fuel at idle but it seems rapid/erratic.
Now at this point my shop mech and I think the same, either replace the complete computer/tbi system, or go carb- intake- stand alone ign, but will there be any power gain doing this?

Thoughts any one?

The scanners are hit and miss as to working on the Dodge ODB1 system. Try the key-dance again on-off-on-off-on.

Check your fuel pressure also check to see if fuel is leaking from the vacuum\vent hose on the voltage regulator.

You will gain nothing really swapping to carb. FI is faster starting, more efficient, better all around driveability. SWapping to a carb will also run you $700-900 in parts if you don't have any plus all the rewiring, etc.

My mech just checked that while I did the 2 fingered typing. he says psi at tbi inlet is 14.9 psi. no fuel in vac line. Am looking at all data right now but can't find the pinout test. Modus normally does other obd1 dodge stuff. Just stumped. Nice w150 you have there. key on off on off on does not flash the light, it stays on steady until started

you should have at least 1 code show up even if it is just a code 55. sound like you might be having a few electrical issues. have you replaced the o2 sensor? i think they are suppose to be replaced every 80,000 miles but usually never get replaced until people start having issues with them. if you do replace it you should use a ntk brand o2 sensor. they are the OE brand. if they are too expensive locally you can order one from rockauto for $30 plus shippping.

Today we spent a few hrs testing while leaving the battery unhooked for 24hrs.
The on off on off on key method doesn't give us anything, not even a 55.

[QUOTE=rickpilgrim;3062997]Today we spent a few hrs testing while leaving the battery unhooked for 24hrs.
The on off on off on key method doesn't give us anything, not even a 55.
The connections in the PCM/TBI harness all display some corrosion, rather severe at the main harness connection by the ECM, the green even goes into the wires an inch or more.
At this point I have decided to carb it, I have a Holley 600 cfm, a holley pressure regulater, eBay an intake and use a www. kmjent.com mopar distributor and salvage yard alt/regulator system and call it a day, more or less. And I would like to Thank Everone for the help and advise on the TBI system diagnosis, even if there is too much corrosion in the wiring to save it IMHO

sounds like oxygen sensor or a possibly stuck fuel regulator wich i believe is located on top the in tank pump should be easy to check on a dump bed, dont feel bad im getting ready to carb my 91d250 it burns rich constently just as well get a little more power out of it only gets 8-12mpg on a good day with the tbi thx w.m.