TBI Issues

[cladiesel]

New to this but I'm looking for a little help. I have an 87 1/2ton 2wd that has a crate motor and transmission in it with less than 5000 miles on them. It ran great for the first year and then started giving me issues like misfiring out of no where. Stalled once and the injectors kept dumping fuel in it. Started out with a new set of plugs and wires. Put in a new distributer. Rebuilt the tbi with new injectors and sensors. Still doing the same thing. Help please!

 

[fast 99]

Hear "doing the same thing almost" every day, many times it's not. Really it isn't a good idea to shot gun these sorts of problems. Bad parts are a real problem. I prefer GM used to any new aftermarket part other than Delphi or Delco.

Forget everything already done. Start with basics, codes, spark, injector pulse, fuel pressure, data if available.

Did you use a Delphi cap and rotor? Off brands will crossfire inside the cap and will not have visible carbon tracking.

bad coil, dirty coil tower, coil primary wires rubbing on bottom of air cleaner

 

[gmbellew]

if it is dumping too much fuel, check the coolant temperature sensor. if it goes bad, it can default to low temp and it makes it run super rich. ALDLDroid and a blue tooth ALDL reader helps a bunch for diagnostic on TBI

 

[fast 99]

if it is dumping too much fuel, check the coolant temperature sensor. if it goes bad, it can default to low temp and it makes it run super rich. ALDLDroid and a blue tooth ALDL reader helps a bunch for diagnostic on TBI

Yes, check pin push back/broken wire and corrosion on connector.

 

[Sgt Gus]

if it is dumping too much fuel, check the coolant temperature sensor. if it goes bad, it can default to low temp and it makes it run super rich. ALDLDroid and a blue tooth ALDL reader helps a bunch for diagnostic on TBI

Suggestions, cheap? I have the basic gm reader. Seems like any Bluetooth device is OBDII. Use an adapter, or OBDII won't work.

 

[gmbellew]

Suggestions, cheap? I have the basic gm reader. Seems like any Bluetooth device is OBDII. Use an adapter, or OBDII won't work.

Getting ALDLDroid from the Google playstore (about $20) and a Bluetooth ALDL reader from 1320 electronics or Red Devil River (about $90) is what I recommend. I think 1320 may also have a free app you can use.

 

[cladiesel]

if it is dumping too much fuel, check the coolant temperature sensor. if it goes bad, it can default to low temp and it makes it run super rich. ALDLDroid and a blue tooth ALDL reader helps a bunch for diagnostic on TBI

Its not that its dumping too much fuel its that it stalled and the injectors kept feeding fuel

 

[cladiesel]

Hear "doing the same thing almost" every day, many times it's not. Really it isn't a good idea to shot gun these sorts of problems. Bad parts are a real problem. I prefer GM used to any new aftermarket part other than Delphi or Delco.

Forget everything already done. Start with basics, codes, spark, injector pulse, fuel pressure, data if available.

Did you use a Delphi cap and rotor? Off brands will crossfire inside the cap and will not have visible carbon tracking.

bad coil, dirty coil tower, coil primary wires rubbing on bottom of air cleaner

Put in a new Jegs distributor along with a new Jegs coil and spark plug wires

 

[gmbellew]

Its not that its dumping too much fuel its that it stalled and the injectors kept feeding fuel

hmmm. not sure about that. I'd think once the ECM sees the engine is dead it would stop pulsing the injectors....

you might check for intake manifold gasket or other vacuum leaks. put a timing light on each plug to see if each plug is receiving spark consistently.

I once had an occassional misfire on a cylinder from a bad wire I found with a timing light.

you might do a compression test and put a vacuum gauge on it while idling to look for clues. maybe engine break in didn't go well and a cam lobe is wiped?

really hard to provide much more without more information.

 

[cladiesel]

Compession test showed all cylinders above spec and the same whether it was hot or cold.

 

[cladiesel]

I'm leaning towards the distributor as my issue. I've been looking at the dui 12620bk as a replacement. Whats the pros and cons anyone thats run one has found

 

[cladiesel]

So this may be a stupid question but why if i pull an injector connector off and the truck stalls out the othet injector keeps pulsing and spraying fuel

 

[cladiesel]

And im looking for a pin out of the ecm connector

 

[gmbellew]

https://www.gmsquarebody.com/threads/1973-1991-service-manuals.14499/

find the drivability manual for your year and start reading, it has the knowledge you seek!

 

[cladiesel]

https://www.gmsquarebody.com/threads/1973-1991-service-manuals.14499/

find the drivability manual for your year and start reading, it has the knowledge you seek!

Thank you