Hello all.

I know that this could be a lot of things but I have done damn near everything I can think of to fix the problem and had no luck.

First, I have a 1992 s10 Blazer 4x4 with the 4.3L Vortec. The problem is that whenever I try to accelerate when the truck is moving, it bogs down unless I floor it. Whenever I reach a hill and try to just keep my speed constant, it takes me flooring it to get it to accelerate. The truck does this no matter if it is warmed up or not. This is causing issues when I am hauling my boat or ATV trailer. The truck sounds great and does not hesitate at all when in neutral or park but as soon as you put a load on the motor it starts acting crazy.

Here is a list of things I have changed so far:

Spider assembly
Spark Plug Wires
Distributor cap / Rotor
Ignition coil
Changed the transmission fluid (thought that maybe there was something wrong there - looked clean and there were no metal shavings)

Things I am going to do this weekend:

New spark plugs
Fuel filter
tps sensor

The truck does not have a maf nor cats - (I knew that they could cause the problem.)

Also - the service engine soon light comes on about 10-15 minutes into driving it, it doesn't change anything about the way the truck drives- (the guy I bought it from neglected to tell me that when I bought it but I dont think it matters much.)

My question is: Is there anything else that I am missing? I know that if it were a vacuum issue the truck would idle rough and would have the same problem if it were in park or neutral. Can someone out there please shed some light on this for me? I am completely out of ideas and I desperately don't want to take it to a mechanic. Thank you all very much for the time and help in advance. I will make sure that I keep this thread open till it is fixed as most of the threads I have seen concerning this are open ended and don't have a conclusion as to what the problem was and how it was fixed.

 

what code is the SES light throwing? When you did the spider assembly, you should have pulled off the EGR valve and cleaned it.

 

check fuel pressure. there is a fitting behind the engine right side. black cap. autozone loans a tester out. (leave retail deposit in case u dont bring it back). MUST hit 60 psi at key on. after u turn key. let it set for 10 min. if it drops below 58ish pumps bad. im saying this IF the spiders ok since u replaced it. did u replace the nylon lines too?

clean egr with brake cleaner with your favorite toothbrush.

 

Ok, went to Autozone and they said that they could not check the ses code because they dont have a ODB1 tester. I did not clean the EGR valve when I changed the spider assembly and yes I did change the nylon lines inside the intake. The spider assembly is a few months old but the issue was still there, though not to this extent after I changed it. I have had a fuel pump go bad on me before in a different vehicle and this does not present with the same symptoms. Not saying that it couldn't be bad but doesn't seem like the problem. I will say that the bogging down problem seems to get worse on an incline. There are times when it wont drop down a gear at all when I am going uphill( Could be my imagination...) I hate to rip off the front top half of the motor just to get to the EGR valve but if you think that it might help, then I will add it to the list of things to do this weekend.

Can you please be more specific on where to check the fuel pressure and would it make a difference since the truck idles like a champ and the only time that it acts up is when I accelerate?

I appreciate the help guys, and any more ideas would be greatly appreciated.

 

Update: I took the EGR valve off to clean it. It was extremely gummed up. It would get stuck in the full open position and there was a lot of carbon build up. The truck is a 92 and I can say with all certainty that this has never been cleaned. I can say that for sure because the bolts were completely rusted solid. I dont know if that is the problem or not because as I was taking the bolts out.... One of the heads snapped off and I am going to have to take the upper intake off to get it out. I hit it with some penetrating oil and let it sit overnight. Just goes to show that nothing ever takes as long as it should. I will post back when I get everything put back together.

 

I have now changed.......

Spark plugs
Spark plug wires
Spider assembly
Distributor rotor
Distributor cap
Ignition coil
Cleaned the EGR
New TPS (throttle positioning sensor)
Fuel Filter
Oil and Transmission fluid

I am officially out of ideas..... I can tell that the truck is running a little better and doesn't bog down as bad as it did but there is definitely still something wrong. Now the SES light only comes on when I get the truck up over 25 and goes off when it goes back down below 25. I hate to say it but I am going to have to take it to a mechanic for a diagnostic. I will post back when I learn anything new just so there can be a resolution to this because everything I have seen online doesn't have a solution.

If any of you have any other ideas before I throw in the towel, please let me know. Have a good day.

 

Ok... I ended up having to take it to a mechanic because I was out of ideas. He told me the MAP and Engine Coolant Temperature sensor were going out so I changed those out. He said that the sensor that controls the timing advance was gummed up pretty bad. I had him clean it out and make sure that it was making a good connection and the after he finished that, the truck ran great. I dont have any problem pulling any of my toys and the truck accelerates as if it were brand new.

All of the things that I changed out and cleaned helped to make the truck run a little better but the thing that really fixed the problem was cleaning the sensor that controls the timing advance. The check engine light still comes on when the trucks rpms get above 2500 but it runs great! I hope that this helps someone else out there because I checked everything I could think of and was never able to find a solution. Thanks again for all the help that people offered. Have a great day all!!

 

This is to little to late. but maybe can help someone now. i was having same symptoms driving me insane. changing parts electrical connectors and on and on. Finally took a look inside the intake. and notice a washed out area in front left side. after inspection the poppet for number 2 cylinder wasn’t seated in all the way. ran like new [QUOTE=Jimmy Williams;586983]Hello all.

I know that this could be a lot of things but I have done damn near everything I can think of to fix the problem and had no luck.

First, I have a 1992 s10 Blazer 4x4 with the 4.3L Vortec. The problem is that whenever I try to accelerate when the truck is moving, it bogs down unless I floor it. Whenever I reach a hill and try to just keep my speed constant, it takes me flooring it to get it to accelerate. The truck does this no matter if it is warmed up or not. This is causing issues when I am hauling my boat or ATV trailer. The truck sounds great and does not hesitate at all when in neutral or park but as soon as you put a load on the motor it starts acting crazy.

Here is a list of things I have changed so far:

]

 

I completely misread this latest post initially since the post and quote were backwards and the quote was not in a gray box. I figured it out when I read the whole thread. Ignore my response since I can’t delete my post.


George