Cold start stalling issue '87 2.9

[El_Capitan]

Well after searching the forum for what seems like forever, I have not found an answer. I'll start with what has been changed or replaced as maintenance, or just plain needing it, since the truck is over 20 years old it's coming up on 250k. All new parts nothing used..

IACV
O2 sensor
ACT sensor
Coolant temp sensor (both of them)
Fuel Injectors
fuel filter
FPR
Cap Rotor Plugs Wires TFI module
TPS
EGR Valve
EGR feedback sensor
EVR solenoid
ALL vacuum lines there are NO vacuum leaks
high pressure fuel pump was replaced about 5 or 6 years
ago...

THERE ARE NO CODES OTHER THAN 11 FOR SYSTEM PASS IN BOTH KOEO AND KOER

Now on to the problem. When the truck is started and the engine is cold it starts then immediately starts to run rough and then will die. You can immediately restart it and it will still run rough then eventually clean up and run decent, and finally upon entering closed loop it runs great, with good power (for a 20+ year old 2.9). This is a new problem it started late last year and has gotten worse over the past month of so. Attempting to drive it when it's cold is difficult to say the least. I have tried a newer ('89) computer but it's the same actually kinda worse. I'm lost as to what this could be, my thoughts are possibly a failing fuel pump maybe the low pressure one?? I'm also a little suspect of the the canister/reservoir thing right before the frame mounted fuel pump. I read those have check valves in them that can stick. My question is has anyone had this problem too? What did you do to cure it? This is annoying as hell. I drive this thing everywhere and I'm afraid it could leave me walking.

Thanks in advance for any help

 

[El_Capitan]

Well went over some of the wiring under the hood today, and found some nasty wires so I cut out the bad parts and spliced some wire new in. Double checked the timing and TPS setting. I also checked the condition of the TFI plug, looks ok. Still have no idea whats up here..

 

[Z3CHYD]

Mine did the same exact thing when i first bought it, but it was only dirty injectors, so i bought some fuel injector cleaner, and it ran fine, but it sounds like something else for u tho, do you possible have the ilde screw adjusted to low for when it's cold?

 

[IMenriched]

there are a lot of grounds, start by rechecking to make sure that they are all good....cab to frame, ground wire on the back side of the head...etc & double check the main battery cables as well.

 

[El_Capitan]

there are a lot of grounds, start by rechecking to make sure that they are all good....cab to frame, ground wire on the back side of the head...etc & double check the main battery cables as well.

I just did a check of the grounds today funny you say that.. I'm starting to think it's maybe an intake manifold leak. It only runs bad when the engine is cold. I really need to find myself a fuel pressure gauge, and see what's up there..

 

[El_Capitan]

So... How about a map sensor? Started it cold today and it was running funky (like usual) fooled around with the vacuum lines, then I completely unplugged the Map sensor (from vacuum source) and It ran the same so I unplugged it from the harness and it ran smooth like it was supposed to

 

[IMenriched]

So... How about a map sensor? Started it cold today and it was running funky (like usual) fooled around with the vacuum lines, then I completely unplugged the Map sensor (from vacuum source) and It ran the same so I unplugged it from the harness and it ran smooth like it was supposed to

give a new one a whirl (MAP sensor that is)...ya tried everything else....trust you've looked the vacuum lines over really good

 

[El_Capitan]

give a new one a whirl (MAP sensor that is)...ya tried everything else....trust you've looked the vacuum lines over really good

Yup I replaced all the vacuum lines..

 

[HndMeDnBroncoII]

use a flamable spray to check for intake gasket leaks not too much at once though and did u check the vaccuum fitting at the brake booster that can leak

 

[El_Capitan]

use a flamable spray to check for intake gasket leaks not too much at once though and did u check the vaccuum fitting at the brake booster that can leak

Replaced the check valve at the booster as well as the gasket, I've tried some brake-clean around the manifold...but.. I've haven't tried it when the engine is cold..

 

[El_Capitan]

Well put in a new MAP sensor... It runs way better, but still a bit shitty when cold. I sprayed brake clean all around the manifold when the engine was cold.. no vacuum leaks found. Just for fun I put on a fuel pressure gauge and fuel pressure is right where it should be. Soo I guess I don't know...