87tonkatoy

So I have been fighting with this thing for some time now... read thread after thread after thread..... so here is the issue the truck sat for bout 6 years. before it sat it passed smog and supposedly has a rebuilt engine. When I got it it was pretty dirty from sitting.

Smoked real bad off the get go both white and black....

First problem found.... valve seals were stuck to valves and were moving with them.

So I pulled head changed valve seals, head gasket, bolts.
Cam timing good ignition timing good (5btdc with jumper)
Compression tests at 175 across all four cylinders.

replaced plugs wires cap rotor........

Computer was putting out tps idl circuit code, o2 code. so replaced tps (tested bad) first one I bought was bad straight out of box would not open circuit on E2 IDL. So re replaced.... replaced o2, adjusted TPS.

Black Smoke terrible..... fouling plugs.

Thought maybe fuel pressure regulator was stuck so replaced that and it seemed better... also cleaned up EGR valve. AFM seems to check out to FSM spec... coolant sensor (in front green plug)seems to also check out at multiple temps...... auxillary air valve seems to function.

tested most all the wires for continuity to computer plugs..... pulled EFI harness inspected splices... including injector splices....

TOTALLY LOST!!!! and broke and frustrated....

so it is still extremely rich... black smoke galore... fouling plugs still causing missing problems.... at least I think thats what causing the missing problems..... starts up nice but smokes terribly at idle and when you rev it only close to WOT does it seem ok........ Truck is not driveable.

87tonkatoy

ohh yeah forgot to put that in the first post... but I jumped fuel pump with cold start injector out and it did not leak... I ran power to it and it works fine.... ran engine with it plugged in and unplugged and no difference.... so pretty sure not cold start injector either...

87tonkatoy

no there is no easy way (i think)... Ive read that you can drill and tap the rail and install an isolator and gauge which I will do eventually anyways cause i would like the guarge in cab.... but for now no I havent tested the pressure.... there is vacuum at the regulator though and I ran it direct to the manifold bypassing switch valve thing just to be sure.. could pressure be high still? how hard to hook to rail for pressure test?

87tonkatoy

also I thought it fired two injectors at a time but the way its wired it must fire all four at once?

87tonkatoy

cat was removed by previous owner... the muffler was rusted out so I welded new exhaust from where cat would have been (was just straight pipe there) all the way to back... so exhaust is open for sure..... Ive been through the first set of hoops for rich running I have been reading quite a bit on here very very very informative so far but its getting a bit more in depth at this point..... it is either something very simple or really complicated.... either way its smarter than me!!!

87tonkatoy

maybe injectors stuck open? all cylinders seem carboned up pretty bad.... wet inside of intake...... new pcv as well....... dont think crankcase pressure is to much but not sure either.... blow by? but smoke is black and smells rich

87tonkatoy

have not checked that..... thats an interesting possibility...... to late tonight but i will check that tomorrow.... should be easy enough just blow on the line disconneted..... or run it with return into a gas can... (only for short time)

87tonkatoy

checked return and vapor lines... they were both really hard to blow through but both passed air.. i opened up above tank and disconnected there to check... since there im going to pull pump out to check tank and intake filter ect.... could the lines be partially restricted? no visual kinks or damage to lines..... intake pulled off so cant start with return into can right now.... going to take advantage of intake off and tap the fuel rail for gauge system but out of money grr!!!! anyhow any other possibilities come to mind?

if the ecu was giving the injectors the maximum possible duration open at all rpms how noticable would it be at idle? bad ecu?

connections seem good but I am in the proccess of cleaning every single connection and using die electric on them and inspectin it all.... cant be a bad thing to have nice fresh connections even if not problem....

87tonkatoy

both lines ok... pulled pump and tank was remarkably clean inside.... all lines clear... except one strange thing there is something hard inside the rubber line from tank to metal line on the vapor line.... is it supposed to be in there? air still flows but restricted for sure.... maybe to prevent gas from sucking up to canister while full/sloshing around?

also any one know where the best place to get the system to put an isolator on fuel rail for in cab fuel pressure gauge?

any more ideas out there? what else could be making an extremely rich condition? I will be putting it back together after I figure way to rig the fuel pressure gauge.... but have a feeling nothing will change

Suttree

I know this is a really old post but I’m having an identical issue. Same setup - cat removed, header... my cold start injector has been wired into a toggle by previous owner for use in extreme cold conditions.

Ive been through the system same as you. Fuel pressure tests at 40psi to the rail. If you’re still on here I’d be really curious to know what you found. Assuming you’ve solved it after 9 years.

I’ve suspected the cold start injector could stuck open. But when I pulled it out from the plenum with the fuel line attached and powered it I didn’t notice any spray. Just figure it’s dead and closed, needs replacing but not responsible for the rich burning issue.

AFM checks out. I’ve tried 3. No change.

O2 sensor tests out to FSM spec.

cleaned and replaced seals on injectors. Tested a second set of injectors. Nada.

New fuel filter.

Replaced and properly installed Throttle Position Sensor.

no air leaks.

Was getting a code for the Knock Sensor potentially triggered by this rich running problem. Without any means to test the sensor I replaced it. Code is now gone.

Broke, frustrated, out of ideas...

Suttree

Well after all this hunting it come down to the very last thing in the chain - the computer. I had the truck out in the in the rain and quickly noticed water gathering in the passenger side floor mat. I pull over and find water coming in down the A pillar and drenching the computer! When I bought the truck back in Nov the first thing I'd had done was have the roof straightened out (previous owner in AB had rolled it and importing it to BC meant getting it through a VI) to have a new windshield fitted. I'd had it out in wet weather before and hadn't noticed the water?! Gonna take it back to the auto body and get it sealed up tight this time.

Replaced the computer and plan to rebuild the old one. Found a number of resistors that didn't meet tolerance.

If anyone else out there encounters this way over rich running check your computer and when you get it replaced don't forget to immediately dump and replace the contaminated oil.