First things first, I am new to this forum and I own a 1995 Chevy K1500 with a 350tbi and automatic trans. The truck has 209,000 miles or so on it and I bought it as a daily driver. I knew the engine was needing to be replaced so I got a longblock from Summitracing and have spent the last month or so swapping the motor in my friends shed in my spare time.

Now the problem I'm running into. I got the motor in and replaced alot of things (starter, alternator, belt, distributor, wires, and alot of other small stuff). I got it started up the other night and let it idle for 25-30 minutes and timed it during that period. After that, I went to give it gas and the RPM gauge started jumping SPIRATICALLY, bogging really bad and the SES light came on. After a little bit of thinking and trouble shooting, my friend and I agreed that it could very well be the new distributor so we swapped the new out with the old one. My friend dropped it in a tooth off, but we turned the distributor clear over to allow for the tooth and it started up and we retimed it. It ran pretty good so we went in to Orielly's the next day and swapped the one I had bought for another one.

We then swapped the old one out with the new one purchased and timed it and when giving it gas its bogging down about the same with the SES light still on. I left (in frustration lol) for the night and came back a few days later when I cooled down a bit. I brought a code reader with me to see exactly what code it was throwing and to my suprise the SES light was no longer on. I started it up and it ran great when at idle and under all the way up to 1/2 throttle (all I went) not a single issue. At least until it warmed up. Once it got warm it started bogging only when goosing the throttle and was fine when easing into it.

Anybody got any ideas as I am COMPLETELY stumped... I honestly don't feel like it's a distributor issue, but IDK maybe people have gotten two new distributors that were bad in a row. Any advice would be GREAT!

 

Anybody??? I'm kind of in a hurry... Have to get the truck out of my friends barn hopefully before Friday. Could it be a bad sensor, clogged injector or anything of that nature?

 

Did you disconnect the electronic advance when you timed it? Is the new distributor still a tooth off?

 

Yea, I found it located under the glove box and disconnected it. The distributor is no longer a tooth off and the timing is set at 0 degrees...

 

Did you scan it to see if the code was stored? It may not illuminate the dash light anymore but might still be in memory.

 

Yea, not a trace of it... Oh, I also forgot to mention that the RPM gauge no longer is jumping around and all gauges now read normal. Basically every so often when you step on the gas when it is warmed up it bogs down to 400 RPM and then goes back to idle at 700. When you give it gas while its bogging down it obviously just gets worse and sounds terrible.

 

How does the fuel spray look inside the TBI? It sounds like a fuel issue if you get on it and it stumbles (lack of fuel), but will run OK if gradually accelerated (pressure is able to keep up). I would check the injector spray and the fuel pressure (pain in the *** on the TBI's). Could be as simple as a fuel filter.

 

How would I go about checking the fuel pressure exactly??? I also thought that may have been an issue.

 

You need an adapter that goes in place of the fuel filter and has a schrader valve on it for a gauge to connect to. There are others who installed a permanent schrader valve on the gas lines going to the TBI unit. I am sure a google search will bring up how to do it that way. I always have used the adapter. It's just a pain because you have to remove and replace the fuel filter.

 

You may also want to check your coolant temp sensor (by the thermostat) as it can start acting up without throwing a code and will be dependent on engine temp.