The car that went bonkers

Hello folks.. First of all thanks for taking the time to read this.. I appreciate any feedback and will tell the whole story from top to bottom.

This is on a 1989 Jimmy 4x4 4.3 v6 with 121,000 miles on it.

First thing that happened that my contribute to this whole madness is that my water thermostate in the car stuck thus overheating it from 140 degrees to about 220 when I hit the driveway.. Water was replaced and car ran fine from their on in for the rest of that day.. THEN they next day came.

(1) Got up started the car and noticed a couple rough spots in idle but they smoothed out..Went out to get on freeway to go to a job interview.. Then it all started
(a) Car would accelerate then all acceleration would JUST stop and car would BOG like it had nothing working...IT would then jump back in to normal running conditions then BOG..run bog run bog..Went about 7 miles and limped it home.

(2) Talked to about 7 different people..was told to check schrader valve on motor but mine does not have one.. Was told that it could be a dirty fuel filter.. I replaced that..same thing going on.

(3) Was given the option of fuel pump regulator or fuel pump going out. Talked to a mechanic he suggested replacing the fuel pump. I did so ( and if you not mechanically inclined DONT DO IT.) Same thing same issue even though the car did seem to respond a bit better.

(4) Also made sure all wires and such in fuel tank were well grounded and checked to make sure everything was clear of rust etc

(5) Now I had a mechanic where I live come over with a basic code tester and we threw it on the car.. NO CODES..He said the voltage on the MAP sensor was running 4.5 on idle which he said might be high.. Also he pushed in the EGR valve and it seemed to make things worse.. SO he said either the EGR or the map Sensor may need to be replaced.

(6) Replaced the EGR valve.. also if I get my hands on the engineer that designed its location IM going tie him to a stump and pour my old engine oil on him (yes bit of mechanics rage here) GOt it done..thats a story in and of itself

(7) Replaced all spark plugs set to .35 gap and wires. All old plugs were black on left bank.. RIght bank was 1 = black = perfect brown 5 = black. ALso checked distributor inside for anything hitting or being wrong ..bit of rust was about it. ( sidenote that whole distributor was replaced about a year ago as the pickup plate rusted so bad it cracked and was really screwing things up)/

(8) Put compression tester on 1 and turned over to get TDC for engine with max compression..the old screwdriver trick dont work on this engine. Now the engine has had the front timing plate removed on this engine so timing it is a bit of a trick.. BUt setting it to base 0 degrees of TDC or BTDC has worked before with a bit of fine tuning..IN any case thats mild stuff I can get fine tuned with little or no issue/ ( side note chevy with their stupid 2 screw set up for distributors sucks big time..Mopar had it right with the snap clip version..more oil on the engineer under my tree :P)


(9) We did run the engine and spray carb cleaner etc at vacum hoses all around the Map sensor the vacum to egr the one to the aircleaner and wherever else we could find it..Had some loose ones so replaced lines and fixed the othere ones..

(10) Was told if idle control valve was stuck open it would be creating an open vacum which could be causing the whole problem. Now get this could not get that tested by anybody and dealer wanted me to bring it in so they could charge me 100 bucks to test in in car..(the part cost 40 bucks ). Replaced that and NO change accept for it seemed to idle smoother when it did idle.

Ive got over 250 bucks in changes in this car.. IM not stupid but im not going to throw more money at this dumb thing till I get some much more experienced people then me to give me feedback (pretty please)

These are the things I have been mulling over.. Car still starts but bogs when accleration and then cuts out hacks pops and now blows crap out the carb which is a joy.. This is a TBI set up so its a noisy one above the carb which makes it very hard to here anything else going on.. Fuel pump clicks and winds up just fine and fuel spray seems fine into TBI body and does increase with throttle up.

Car will idle sometimes fine and I can rev it up ..then as it winds down I goose it and get burping and cutting out.. THIng that is throwing me is it CUTS OUT for no reason..not ,like it just backfires or something for no reason it just BURPS nothing for a bit fan throttle then BOG then go.

I have been told that the 4.3 v6 had manifold vacum leak issues.. I have been told it can be the map sensor.. I have been told the brain box.. I have been told the fuel pressure regulator. (side note all fuses in box are fine and not burned out) ..

Any help and I mean any help HELP.

And as Men at work said..Blood on the pillow of my bed explains the pain thats in my head ...:(:runaround::runaround::runaround::runaround:

Proper testing will lead you to the problem.

Confirm proper fuel pressure.
Good hot blue spark to all spark plugs.

Have you checked base timing?

Poping back the intake?
If so check for .
Plug wires crossed or bad camshaft lobe/push rod or even cracked dist cap or moisture in it?

Also.
Better recheck that Map sensor reading and engine vacuum reading.
What is map sensor reading and engine vacuum at idle and at 2K RPM?

Confirm proper fuel pressure.
Good hot blue spark to all spark plugs.

Ok these I will do tomorrow

Have you checked base timing?

I reset the timing to base of 0 degrees advance..very hard to tell exact timing as number do not exist on front of my engine..prob have to buy some timing tape and find base TDC for 1 and go from thier..best i can do with that

Poping back the intake?
If so check for .
Plug wires crossed or bad camshaft lobe/push rod or even cracked dist cap or moisture in it?

Will double check sparkplug wires.. Rest Id have to look at after popping the manifold..PREFER to keep this to an extreme response or last action as it requires a ton of work time and money.

Also.
Better recheck that Map sensor reading and engine vacuum reading.
What is map sensor reading and engine vacuum at idle and at 2K

Ok we will double check those for u as well.. Thanks for the tips much appreciated

Hello folks.. First of all thanks for taking the time to read this.. I appreciate any feedback and will tell the whole story from top to bottom.

This is on a 1989 Jimmy 4x4 4.3 v6 with 121,000 miles on it.

First thing that happened that my contribute to this whole madness is that my water thermostate in the car stuck thus overheating it from 140 degrees to about 220 when I hit the driveway.. Water was replaced and car ran fine from their on in for the rest of that day.. THEN they next day came.

(1) Got up started the car and noticed a couple rough spots in idle but they smoothed out..Went out to get on freeway to go to a job interview.. Then it all started
(a) Car would accelerate then all acceleration would JUST stop and car would BOG like it had nothing working...IT would then jump back in to normal running conditions then BOG..run bog run bog..Went about 7 miles and limped it home.

(2) Talked to about 7 different people..was told to check schrader valve on motor but mine does not have one.. Was told that it could be a dirty fuel filter.. I replaced that..same thing going on.

(3) Was given the option of fuel pump regulator or fuel pump going out. Talked to a mechanic he suggested replacing the fuel pump. I did so ( and if you not mechanically inclined DONT DO IT.) Same thing same issue even though the car did seem to respond a bit better.

(4) Also made sure all wires and such in fuel tank were well grounded and checked to make sure everything was clear of rust etc

(5) Now I had a mechanic where I live come over with a basic code tester and we threw it on the car.. NO CODES..He said the voltage on the MAP sensor was running 4.5 on idle which he said might be high.. Also he pushed in the EGR valve and it seemed to make things worse.. SO he said either the EGR or the map Sensor may need to be replaced.

(6) Replaced the EGR valve.. also if I get my hands on the engineer that designed its location IM going tie him to a stump and pour my old engine oil on him (yes bit of mechanics rage here) GOt it done..thats a story in and of itself

(7) Replaced all spark plugs set to .35 gap and wires. All old plugs were black on left bank.. RIght bank was 1 = black = perfect brown 5 = black. ALso checked distributor inside for anything hitting or being wrong ..bit of rust was about it. ( sidenote that whole distributor was replaced about a year ago as the pickup plate rusted so bad it cracked and was really screwing things up)/

(8) Put compression tester on 1 and turned over to get TDC for engine with max compression..the old screwdriver trick dont work on this engine. Now the engine has had the front timing plate removed on this engine so timing it is a bit of a trick.. BUt setting it to base 0 degrees of TDC or BTDC has worked before with a bit of fine tuning..IN any case thats mild stuff I can get fine tuned with little or no issue/ ( side note chevy with their stupid 2 screw set up for distributors sucks big time..Mopar had it right with the snap clip version..more oil on the engineer under my tree :P)


(9) We did run the engine and spray carb cleaner etc at vacum hoses all around the Map sensor the vacum to egr the one to the aircleaner and wherever else we could find it..Had some loose ones so replaced lines and fixed the othere ones..

(10) Was told if idle control valve was stuck open it would be creating an open vacum which could be causing the whole problem. Now get this could not get that tested by anybody and dealer wanted me to bring it in so they could charge me 100 bucks to test in in car..(the part cost 40 bucks ). Replaced that and NO change accept for it seemed to idle smoother when it did idle.

Ive got over 250 bucks in changes in this car.. IM not stupid but im not going to throw more money at this dumb thing till I get some much more experienced people then me to give me feedback (pretty please)

These are the things I have been mulling over.. Car still starts but bogs when accleration and then cuts out hacks pops and now blows crap out the carb which is a joy.. This is a TBI set up so its a noisy one above the carb which makes it very hard to here anything else going on.. Fuel pump clicks and winds up just fine and fuel spray seems fine into TBI body and does increase with throttle up.

Car will idle sometimes fine and I can rev it up ..then as it winds down I goose it and get burping and cutting out.. THIng that is throwing me is it CUTS OUT for no reason..not ,like it just backfires or something for no reason it just BURPS nothing for a bit fan throttle then BOG then go.

I have been told that the 4.3 v6 had manifold vacum leak issues.. I have been told it can be the map sensor.. I have been told the brain box.. I have been told the fuel pressure regulator. (side note all fuses in box are fine and not burned out) ..

Any help and I mean any help HELP.

And as Men at work said..Blood on the pillow of my bed explains the pain thats in my head ...:(:runaround::runaround::runaround::runaround:

Don't listen to ANYONE, ever, about ANYTHING in life, who 'tells' stuff to you. SHOW ME!!!

How are you knowing the thermostat stuck? If it was open at any moment, it did not close and stick shut. Promise...

"Jump back" to normal operation? That's probably electrical...

It has a schrader valve. Just like a bike tire valve stem. You HAVE TO find it, and you HAVE TO check fuel pressure.

You did NOT replace the fuel pump at someone's 'suggestion', did you??? A mechanic should have SHOWED YOU HIS PRESSURE GAUGE, PLUGGED INTO THE SCHRADER VALVE, AND SHOWN YOU WHAT SPEC FUEL PRESSURE IS SUPPOSED TO BE. If you did, DO NOT GO TO THAT MECHANIC AGAIN.

Car SEEMED to run better? You have to know for sure. Unless you were replacing a part that you weren't sure is bad, and it was the plug and PRAY diagnostics repair...

Pushing on the EGR valve will make the motor stumble, since it is allowing momentarily a vacuum leak. Sorry you replaced it, THAT was a waste...

A trouble code for X sensor does not mean the sensor is bad necessarily. A cut wire will make the computer think a sensor is bad.

Get fuel pressure first. Let's untie this ball of string, without wasting time and cash.

Air, fuel, fire.