1990 dodge b250 318 tbi... pulled codes from ecu... results= 12, 21, and 55. Fuel system is very rich causing flooding and stalling. I would appreciate any input you can provide. I also had a problem where the ignition coil kept burning out. The van did not have a ballast resitor, so I put a two wire resistor inline. This saved my coil from overheating, but I am still having trouble with rich fuel and poor or no driveability. I replaced cap, rotor, coil, and pickup in the distributor recently, but did not help. Plugs and wires are recent within 10k miles.

K1500 PICKUP. ? 5.7 TBI. GAS
i will assume eng. compression good and spark good and timed by the book.
it's staving for fuel.!
fuel pressure not at spec,
fuel pressure regulator bad.
injector clogged (injectors screens inside packed)
bad fuel (was bad now bad fuel is in all that path)
MAP sensor bad or clogged up. EGR stuck open
meter mAp pin out,1.5vdc out,keyon to 4.5V WOT (wide open throttle)

we test fuel pressure 3 ways
key pressure
idle
and WOT
the manual covers that, buy the service manual?
so the pressure specs for TBI are at hand./?
there is no fuel rail like MPI so has very odd connections to do pressure tests TBI. (below)
you do know most injectors have 10micron screens inside,and only ultra sonic reverse cleaning cures them right? (or new injectors) I send mine out for pro cleaning, (Usonic)

the hard part of 1995 TBI is getting the TBI specs.
the manuals were 500 pages paper and nobody digitized all page or skipped most the Injection pages.
it is a problem but the used books are sold at EBAY
from GM (real)

rumor has it
"In stock form a tbi operates 11 to 13 psi running a bit higher makes them run better to a point of about 14.5"
the TBI if you look close has a FPR, seen here
it must be good.(diaphragm)
some TBI have 2 injectors, start+idle (and fast run)
as seen here

https://www.rockauto.com/en/catalog/chevrolet,1995,c1500+pickup,5.7l+v8,1031443,fuel+&+air,fuel+injection+pressure+regulator,6124


next up how to read the pressure (tap ports)
I think this is a returnless system (early)
so they make up filter tap point. fuel. or TEE fitting.


https://www.reddit.com/r/MechanicAdvice/comments/10nz5rd/best_way_to_check_fuel_pressure_gm_tbi/

PICKUP not VAN sold new 6 engines, then, 5.0L yours.
when did it last run good, last week/month/year /????????
well in shop we'd check all fuses..
1995 is long in tooth for ECU problems bad caps
he ECU runs EFI and spark both ( a huge job)
runs ,stalls and not restart.
what you failed to I real testing and is not the starter at all.
first (besides good engine)
is spark if will not start, cranked spark is first unless you learned how to do he ECU CEL blink codes.(more later)
I will not stop and see what is there in your shop manual (service)
5.0L v8 gas, engine, this the horrible old TBI system? 1 injector>?
or is this the MPI , 8 injector engine,
has distributor spark and must be timed correctly to work
the CMP is in the dirtributor,
the CKP is on the crankshaft.
I test for spark first using both ways
a test spark plug, gaped right, (new plug not old) and if spark is good great.
if old plug is fouled;, carbon, oil soaked or soaking in raw fuel
the fuel seen now is flooding,
I then use a timing lite (yes even works cranking dead engines)
and make sure static time is correct the DIZZY.
if not it must be set correctly now. per the manual on car.
I use the light to make sure al spark wires spark(mag pickup lamp)
if not the distributor or the CKP sensor is dead.

if all that seems ok out comes my trusty Instant start spray can.
Air cleaner off, spray fuel here, 3 second blast , crank, and repeat
until it runs 3 seconds to burn up you fuel sprayed.
see? the engine is not dead, now, or IS deaD.
IF FLOODING SEEN, crank with foot throttle depressed WOT
and the trick cuts off the injector and the flood is cleared
even starting an old engine like this with 5% throttle can hide a bad IAC air valve and allow it to start and the a active right foot to keep his beast running.
but spark is first it must be good x8 and battery fully charged.

this 5.0L is a TBI injected engine, 1/2 injectors not 8 with MPI
some have a starting only injector then the signal; main to run
theTBI is old and its pressure regulator can be bad./

one trick I use (means tactics) Is that I kill the fuel pump fuse or its relay pulled.
this hides the bad TBI fully and now test fuel works all I want showing me it is just bad spark or bad fueling just doing that.
the TBI can fail 3 ways, dead, way to lean or way to rich
the latter is flooding and WOT cranking can clear floods.

the goals ARE TO FIND?.

1. bad engine
2. bad spark
3. bad fueling

OR CATS MELTED, OR EGR STUCK WIDE OPEN BUT THOSE TO 2 THINGS MAKE THE ENGINE BAD. SO IS THAT.#!

TBI CAN BE A BIG PAIN
NOW THE FLASH CODES, EVER LEARN THAT/
THIS PRE 1996 CAR USA HAS OLD CHEVY OBD1 DIAGNOSTICS
most folks never heard of it now but gee it is in the manual for sure.
fl\ash codes (blinks) code 13 to 55 or more with A/t box.

steps to do this,
key off
find ALDL connector (DLC modern named ) data link conn.
see my photos. (books says under DASH) some near column
The diagnostic trouble codes can be read by grounding test terminal B. The terminal is most easily grounded by connecting it to terminal A (internal ECM ground).
jumper B to A
THEN KEY ON AND CRANK THE ENGINE (BATTERY ALWAYS CHARGED FULLY BY THE TECH)
AND CRANK FOR 10SECONDS, NO MORE
THE RELEASE THE KEY (NOT OFF)
SEE THE LAMP BLINK OUT FAILURES CODES.AT CEL CLUSTER LAMP, THE CHECK ENGINE LIGHT BLICKS AND THE LAMP MUST BE GOOD. (many are removed by evil sellers)
quote
flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the ECM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent.
then other blink codes are next if stored or are live errors.
2 kinds live and stored, both matter to any tech.
after Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest.
sorry for long post but 1995 cars are super hard to diagnose.
even bad CAPS in the ECU are common now, and show stoppers.
CODE 42 OR 43 IS BAD SPARK , I'D NEVER Forget to ask the PCM what errors there are, ever, ask it and win,
also the lack of errors has meaning too.
full stop this is what I'd do the first hour.

ALDL jack (assembly line data link ) conn. CHEVY ONLY !

Suspect (potentially) either a stuck injector, or a failed/failing fuel pressure regulator. One sign of a failed fuel pressure regulator can be gas in the oil. (I suffered that side effect, along with bogging, and black smoke rich running, worsening as warmed up, turned out to be fuel pressure regulator). If the injector is loose in the throttle body, or has bad o-rings, can also cause some wonky behavior. Good luck.

Well, even the early models in 1986 had an onboard computer. It kind of sounds like the ECU or brain is not working properly. For the problems you have, there should be Codes set. But part of the engine controls apparently are causing the following.

The fluctuating idle can be the controls going from rich to lean and then back to rich. Go to Autozone.com and register your car for free and then print out the chassis wiring diagrams and fusebox layout.

You may find a PCM or ECU relay is bad. The water temperature sensor cancels the cold start loop. If the water temp sensor is bad, the car will run rich. Some cars have 2 water sensors, 1 for the dash and a second for the engine management system. You want the engine water temp sensor for the engine controls.

Both the fuel pressure regulator and the MAP sensors can be tested. There is a test tap on the fuel rail for the fuel pressure. The gauges can be borrowed under the Tool loaner programs at big autoparts shops.

You can probably replace the water sensors for a few dollars. Take the MAP in for testing.

After that you probably should weigh the more expensive guesses against hooking the car up to a first class scanner. Autozone, Oreilys, and Advance have free scans. Yours is an older system and their equipment varies much from location to location.

Looking at the price of parts versus wasting gas and drivebility problems, you might get into an accident or have a big tow bill if it stalls.

Have you cleaned the throttle valve and the air bypass idle speed control valve? If not do that. When they get really gummed up from backwash from the combustion process they cause this problem of stall on cold start.

If it acts like it is flooding while idling, but it runs fine on the road, it could be running too rich and flooding it out due to leaking injectors, bad fuel pressure regulator, or excessive fuel pressure.

I would start by replacing the Fuel Pressure Regulator since it doesn't cost as much as the injectors.
Check your fuel pressure using a Fuel Pressure Check Gauge to see if the fuel pressure regulator is maintaining the proper pressure.

Vacuum is attached to the Fuel Pressure Regulator to control system pressure. When the fuel pressure regulator is not functioning properly it causes the fuel pressure to be above normal operating pressure. This condition causes excess fuel to be injected causing a rich mixture that produces black smoke.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Oxygen sensor. They tend to fail by sending the engine computer a steady lean reading. the computer then runs the TBI rich in order to compensate for the false lean condition.

Also, the Engine Coolant Temperature sensor. If it fails and shows the engine to be ice cold when it is really warm, the computer will schedule lots of fuel.

Intake Air Temperature sensor. same result as ECT above. Computer sees nothing but cold dense air all the time and schedules more fuel.

Stalling and running rich. I have seen this before on a Camero. The fuel pump was weak. Not making enough pressure. This caused the fuel injector to DRIP gas instead of SPRAY gas. This caused the fuel to flow into the cylinder in a liquid form, and it did not burn well. We put in a new fuel pump and the car came to life. Good luck.

Need to check for fault codes. Possibly a faulty sensor causing the fuel system to run rich or lean.

yes it can but you may have a coolant temp sensor acting up which causes the computer to open the injectors to much which can also cause this 02 sensor code. when it stalls do u have spark and fuel pressure.