TBI Problem - Any Ideas?

J.C.

J.C.

Volunteer
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Joined
Apr 18, 2005
Location
Greensboro, NC
Finally got around to messing with the TBI 350 SBC motor I got several months ago. Engine will fire up every time but will die out in a few seconds to a minute. New Affordable Fuel Injection harness and computer chip, IAC, TCS, O2, cap and rotor, fuel pump. Timing set properly (pretty sure). At key on check engine light flashes and then stays on until engine is started. Jumping pin A and pin B on the ADL connector makes code 12 flash continuously but no other codes present. Looking for any ideas from the TBI gurus. Any chance it could be the TPS? BTW, thanks to Yager for help with getting the distributor installed properly and timing!
 
Is this it dieing out just trying to idle ? or with you providing some throttle to help it ?

What did you set the timing to ? and what is it set to on the chip?

what is the numbers on the ECM ?
 
yager said:
Is this it dieing out just trying to idle ? or with you providing some throttle to help it ?

What did you set the timing to ? and what is it set to on the chip?

what is the numbers on the ECM ?
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The ECM is a 1227747 AKDY (the number the chip is for) also on the case 862271, E380891064, 16082271.

The pump is a new NAPA P74017, the pump recommended on Pirate for this application. It is running straight from a gas can to the TB via the pump. I guess is could be pressure as I haven't checked but it's putting fuel in the TB.

Trying to idle? It will continue to run if I give it trhottle but will stumble and die if I hold it at any particular place for too long. Have to keep blipping it.

I set timing to 0, what Affordable Fuel recommended, with the timing wire that goes to the dist unhooked.
 
did you plug the brake booster vacuum leak ?

Where is your map sensor vacuum hose hooked up to ?

Cap off all other open ports on the TBI?

When you blip the throttle it puts you into AE (accelerator Enrichment aka pump shot) so that says your definitely not getting enough fuel or your getting to much air.

Are your throttle blades able to close completely ? (or close to it)

Are BOTH injectors firing ?
 
Yep plugged the booster vacuum.
Map runs to the front of the TB.
All others capped.
Looks like blades are pretty much flat.
Both injectors firing.
 
One of the guys in our club got an affordable harness and chip, his ran like shit. Swapped a factory computer in and it runs a hundred times better. I'm pretty sure they tried different sensors, etc. but this is the only thing that worked. Maybe affordable's chip burning skills suck.

On a sidenote, I just ordered one of their harnesses, seems to be the way to go, but I will not be running a chip from them.
 
Is your pump grounded very well?
And is the gas can sitting lower than the pump? The pump should be below the fuel level if at all possible.
 
R Q said:
Is your pump grounded very well?
And is the gas can sitting lower than the pump? The pump should be below the fuel level if at all possible.
Click to expand...

10-4 on both. Pump ground straight to battery, pump mounted to top of trans, gas on floor.
 
90xj said:
One of the guys in our club got an affordable harness and chip, his ran like shit. Swapped a factory computer in and it runs a hundred times better. I'm pretty sure they tried different sensors, etc. but this is the only thing that worked.
Click to expand...

Thanks, I'll try the original chip today and repost results.
 
Not sure but I think I remember a few people having problems running that pump "P74017" on a TBI systems. If chip don't fix it. I'd check fuel pressure next.
 
Def check pressure, if you have any problems with chips or whatnot might want to get ahold of Brian at TBIchips.com he burns custom chips for cheap and also supply's the chips for wynjammer. The cool thing is he's located in Randleman so he's local, I'm actually heading over there today to Dyno tune my Z71 now that I have the new motor finally built.
 
OK, I'm heading backwards :( Pulled the Affordable Fuel chip and went looking for my old chip. Found it damaged, pins broken, in a box :( Put the Affordable chip back in and now the check engine light flashes continuously and the injectors don't fire! Might have damaged the new chip? This is getting frustrating, may have to call in the cavalry :) Thanks for all the ideas and tips.
 
John what year is your TBI unit from ? (IIRC you said 95?) Possibly could be part of the problem ? Pull your injector wires off and see what 2 paint colors are on the top of them, and/or write the numbers down..

I was thinking about this last night... and I have a suspicion that your TBI unit (built in regulator) and injectors could be from a 94/95 higher pressure setup while your chip/tune is for a normal lower setup 7747 ECM, This could cause the extreme richness you mentioned.

If this is true, your ECM thinks it has larger injectors with low(er) pressure and is calling for longer on time, when in fact you have smaller injectors with more pressure (~30psi). Your essentially flooding the engine, this could account for the extreme richness your seeing and that it 'runs better' with a vacuum leak.. (I find it hard to believe a purchased chip is SO far off it won't run the engine, even if poorly)

I have some misc. TBI parts I'll bring next week and we'll get to the bottom of it..

side note- I'm sorta wondering if this is part of Ricky's lower than expected HP numbers..
 
John, I have messed with these same things that you are struggling with- and more. Try as best you can to get the numbers list off of Howells web site about compatible parts. You may eventually get it to run with mis-matched parts, but it might not be right. It took me 3 years to finally understand that. I finally gave up and had to buy all new everything from a take off rig at the JY. Mixing and matching just doesnt work, the signal tolerances are just too tight. If all else fails, I have trail spares of everything that I might could Oops to you- but its all for a 93 setup. I will dig it all out and see what the numbers are when I get a chance. I am thinking along the lines of ECM not bring tuned to your injector size. I got a 350 TBI that somebody had stuck 305 injectors in -and I didnt realize it, that really buggered me up for awhile. It ran, but really quirky.
 
my spare comp is a 1227747 860061 E380892224 16120061
 
This is an 89 truck engine rebuilt with a newer block. Thing is, it was pulled from Firetoy's rig and was running OK. Ran OK for me when I first fired it up albeit with a huge vacuum leak (brake booster not hooked to anything) and lots of smoke but after the rotor button crashed I swapped in a new cap and rotor. At this time I discovered that the old cap was apparently wired wrong and the timing appeared to be out about 90 degrees, ie rotor pointed to 3 o'clock at TDC. Haven't been able to get it to run decent since :( The driver side injector is GM5235206*RPD/6159 GM, the passenger side is GM523506*RPD/6149 GM. Got the Moates ZIF adapter and chips on the way, should be here tomorrow or Saturday then hopefully Mike Yager can help me get it straightened out :)
 
Ok, will dig out my spare throttle bodies tomorrow after work and see what the injectors are, numbers wise if I find a matching pair that are what you have I will put them out so you can pick them up- if Im not home. I must be missing something, but why does it matter where the rotor is pointing, as long as its at #1? I guess what I am saying is that if you have enough room in your bay to turn that sucker completely around, what would it matter? I have heard of them running 180 out of phase, but never 90, I didnt think that they would compensate nearly that much in timing. And yes from what I have seen a TBI base timing is from 0 to 4 depending on vehicle, the only good info is on the donors hood/grill tag. Even the dang dealer wont give you reliable info. One more thing, you arent dealing with a mix of Pontiac and Chevy stuff are you? The dizzys arent the same.
 
You are correct on the dist placement as far as I know. The issue is having enough room to turn it around and I'm limited by the intake and dist connections, otherwise I guess it wouldn't matter. Like I said, it did run before I fixed it :)
 
Update and request for any ideas.

It seems my AFI chip went bad, Yager couldn't read it with his chip burner so he burned me a stock replica of what I got from Firetoy. Motor will now start everytime, nice pattern on the injectors, in line fuel pressure gague reading 8-11 psi while running. Engine will not idle. I can keep it running by staying on the throttle or by shooting starting fluid into the TB when it gets ready to die but it will run nicely for 30 secs to a minuite and then die out. Any ideas? Regulator?
 
CYJKrawler said:
Update and request for any ideas.

It seems my AFI chip went bad, Yager couldn't read it with his chip burner so he burned me a stock replica of what I got from Firetoy. Motor will now start everytime, nice pattern on the injectors, in line fuel pressure gague reading 8-11 psi while running. Engine will not idle. I can keep it running by staying on the throttle or by shooting starting fluid into the TB when it gets ready to die but it will run nicely for 30 secs to a minuite and then die out. Any ideas? Regulator?
Click to expand...


EGR???
 
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