TBI start up troubles

[RubyRed4x4]

Hey guys, first post here...

my 84 K10 with a 350 TBI out of an 89 is giving me some start up and idle issues...when i purchased it it already had the motor, but the fuel pump was that of a carb vehicle(holley red, 7 psi max). it ran fine, but cut out when I really got on the throttle. so I changed the fuel pump to an inline pump that pressure matched TBI settings. now when i start the truck it runs really rough like it is gonna die, but doesn't until the motor warms up. once the motor is warm it still surges a little and high idols sometimes, but drives great. this is my first square body so I am looking for some insight on potential causes for this symptom. i have checked for vaccum leaks with no avail and the EGR holds suction...HELP!

 

[Jims86]

Hey guys, first post here...

my 84 K10 with a 350 TBI out of an 89 is giving me some start up and idle issues...when i purchased it it already had the motor, but the fuel pump was that of a carb vehicle(holley red, 7 psi max). it ran fine, but cut out when I really got on the throttle. so I changed the fuel pump to an inline pump that pressure matched TBI settings. now when i start the truck it runs really rough like it is gonna die, but doesn't until the motor warms up. once the motor is warm it still surges a little and high idols sometimes, but drives great. this is my first square body so I am looking for some insight on potential causes for this symptom. i have checked for vaccum leaks with no avail and the EGR holds suction...HELP!

Ok...here we go!
Is the check engine light on?
Check the Vacuum hose going to the MAP sensor. The MAP sensor is responsible for determining the engine's fueling needs by measuring Vacuum. The lower the vacuum, the richer the fueling, and vise versa. The line to the MAP should be running off of the rear vac port of the TBI.

While your at it, Make sure your timing is set at 0* BTDC. Don't forget to disconnect the timing bypass wire. Its a black plug, with a tan wire, should be near the brake booster, if the conversion was done right.

Also check the throttle shaft for slop...should be tight, if not, this could be a contributing factor.
Is the engine all stock, or are there any mods that you are aware of?

 

[RubyRed4x4]

Ok...here we go!
Is the check engine light on?
Check the Vacuum hose going to the MAP sensor. The MAP sensor is responsible for determining the engine's fueling needs by measuring Vacuum. The lower the vacuum, the richer the fueling, and vise versa. The line to the MAP should be running off of the rear vac port of the TBI.

While your at it, Make sure your timing is set at 0* BTDC. Don't forget to disconnect the timing bypass wire. Its a black plug, with a tan wire, should be near the brake booster, if the conversion was done right.

Also check the throttle shaft for slop...should be tight, if not, this could be a contributing factor.
Is the engine all stock, or are there any mods that you are aware of?

ok...vac line to map sensor seems to be good. no check engine light. i can't read the timing, it appears to be rusted...engine is all stock that i know of, does have exhaust with no cats, but stock exhaust manifolds. i fired it up after all day being at the fire station and it ran pretty decent within a few seconds...

 

[RubyRed4x4]

also, i took a look at the injector pattern and it appears to be very rich...also it is spitting of alot of unburned fuel out of the tail pipe.

 

[Jims86]

also, i took a look at the injector pattern and it appears to be very rich...also it is spitting of alot of unburned fuel out of the tail pipe.

Clean that timing scale off and get it readable...its very important to make sure it is set properly, so we can cross out improper timing from the list.
Maybe a compression check is in order, but until you can get to that, I would recommend checking all of the engine grounds, and the battery ground as well, cleaning your plugs, then letting the tank run to a little under 1/4, then dump in 2, yes, 2 cans of seafoam, or berrymans fuel system cleaner. Drive it around...Highway speeds in 3rd gear would be best. Take a few spare gallons with you in a can, anless you know your gas gauge really well.

it will always smell rich, due to the cat missing. Also, if you have not done so, get an AC Delco replacement coolant temp sensore, which is located next to the thermostat housing.

 

[RubyRed4x4]

Jim's...thx so much for the help brother! I know with the deleted cats it will always smell rich, but it has never spit fuel out the tail pipe to this level before the new fuel pump. Also, I installed an inline fuel pressure gauge about 18" before the throttle body and it is pegged out at 15psi...think my fuel pressure regulator is bad at the throttle body? I am gonna try to get all of this looked at in the next couple days. Plugs definitely don't look new...is it kosher to just change the plugs without changing the wires?

 

[Chevyguy]

Jim's...thx so much for the help brother! I know with the deleted cats it will always smell rich, but it has never spit fuel out the tail pipe to this level before the new fuel pump. Also, I installed an inline fuel pressure gauge about 18" before the throttle body and it is pegged out at 15psi...think my fuel pressure regulator is bad at the throttle body? I am gonna try to get all of this looked at in the next couple days. Plugs definitely don't look new...is it kosher to just change the plugs without changing the wires?

If the wire's look good just change the plugs.

Clayton