TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

need a little TBI help

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Old Jan 30, 2012 | 01:46 PM
  #1  
Seafarer12's Avatar
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Joined: Jan 2012
Posts: 102
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From: Outside of Austin TX
Car: 92 GMC K2500 LD
Engine: 350 TBI with some mods
Transmission: NV4500
Axle/Gears: 3.73
need a little TBI help

Hey Guys.
I just did an engine swap on a TBI truck 92 model. The engine was a rebuild out of an 88. While the engine was out I changed the cam, lifters and chain, CS1014R RV cam. Edelbrock TBI Manifold, 15lb regulator spring, new throttle body (stock), I put a Harris performance chip in it.

Anyway I got it started up but it is running like crap and over heating. I had some issues getting it to fire up (dist was 180 out) but after that it fired right up running a bit rough but not bad. I pulled the advance wire and set the timing to 0. I plugged it back it and attempted to seat in my cam. It ran a few minutes and started over heating. I tried burping it. It wouldn't even idle without over heating. I pulled the tstat and drilled a 1/8" bleed hole, jacked the front end up. I finally got it so where it would run about 240 at idle. As soon as I shut it down and give it a few minutes it cools right down to 120 (like I have an air pocket) I am getting good flow through the radiator and even pulled the temp sender out to make sure there wasn't air. I put the stock prom back in with no difference.


It is also running very bad. It labors to get to 3k rpm and backfires through the exhaust when I let off. Its running a little rough and very slow to respond. I took it down my driveway and it has no power at all. I pulled the valve covers and adjusted the valves, rechecked the plug wires and rechecked the timing. I am running out of things to check.


Thanks for the help.
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Old Jan 30, 2012 | 02:51 PM
  #2  
RFmaster's Avatar
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Joined: Jan 2007
Posts: 1,873
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From: OC CA
Car: 75 Beast
Engine: 383 +EBL Flash
Transmission: 700R4
Axle/Gears: 4.11 with 33"
Re: need a little TBI help

I run CS1014R in my newer 350 engine that I dropped in over the XMAS break. It should run like a champ as it is very TBI friendly cam shaft. I assume that you are not running super high compression pistons and used correct head gasket. If you do not mind list your engine particulars.

To get around a possibility of air pocket in a fresh engine I remove t-stat and poor coolant into intake (with radiator filler open). This allows coolant to fill engine block and heads slowly - forcing air pockets. I also run heater hose from intake manifold into radiator - this will by pass t-stat and will purge air out.

Assuming that all other things are correct check spark-plug wires - make sure that all cylinders are firing. A swapped cylinder pair is a common problem - this will cause rich condition (extra oxygen dumped into exhaust along with un-burnt fuel).

//RF
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Old Jan 30, 2012 | 03:38 PM
  #3  
Seafarer12's Avatar
Thread Starter
Member
 
Joined: Jan 2012
Posts: 102
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From: Outside of Austin TX
Car: 92 GMC K2500 LD
Engine: 350 TBI with some mods
Transmission: NV4500
Axle/Gears: 3.73
Re: need a little TBI help

Thanks RF,
I figured out one of my problems. One of my injectors wasn't firing. I had sent them off to get tested and cleaned. I need to get on the phone and get on someone. I swapped it out with another injector and that thing came alive. It ran like a scalded dog. I am still over heating but I am going to try getting a delco sensor and see if that helps. The amount I have circulated through should taken care of any air pockets.
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Old Jan 31, 2012 | 10:24 PM
  #4  
Seafarer12's Avatar
Thread Starter
Member
 
Joined: Jan 2012
Posts: 102
Likes: 0
From: Outside of Austin TX
Car: 92 GMC K2500 LD
Engine: 350 TBI with some mods
Transmission: NV4500
Axle/Gears: 3.73
Re: need a little TBI help

I put a delco temp sensor in it and all my temp problems vanished except now I think my bleed hole is allowing too much flow with the cooler weather. Oh well if it isnt one thing it is another. But overall I am happy with it. It runs like a champ now.
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Old Feb 1, 2012 | 09:16 AM
  #5  
RFmaster's Avatar
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Joined: Jan 2007
Posts: 1,873
Likes: 0
From: OC CA
Car: 75 Beast
Engine: 383 +EBL Flash
Transmission: 700R4
Axle/Gears: 4.11 with 33"
Re: need a little TBI help

Originally Posted by Seafarer12
I put a delco temp sensor in it and all my temp problems vanished except now I think my bleed hole is allowing too much flow with the cooler weather. Oh well if it isnt one thing it is another. But overall I am happy with it. It runs like a champ now.
The bleed hole should not make that much difference - it just takes a bit longer for engine to come up to final temperature. Good - a simple CTS swap solved the problem!

//RF
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Old Feb 1, 2012 | 06:56 PM
  #6  
Seafarer12's Avatar
Thread Starter
Member
 
Joined: Jan 2012
Posts: 102
Likes: 0
From: Outside of Austin TX
Car: 92 GMC K2500 LD
Engine: 350 TBI with some mods
Transmission: NV4500
Axle/Gears: 3.73
Re: need a little TBI help

Yep sometimes it is worth the few bucks extra buy delco stuff.
Reply
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