We had a fuel pump go out in a 89 TBI after dropping in a new 305 Engine with LT4 cam Vortec heads bla bla bla and so on. Anyways first off we couldnt get the timing set right. Well that wasn't the problem it ended up being that the fuel pump would not get wenoug fuel to the engine to run right. Ok fine new pump is in and we have plenty of pressure. So now what? We cant get the base timing set because the car is running like **** and it will just up and die.
So here is the smptom it is WAY TOOOO RICH!!!!!!! at idle black smoke is coming out of the exhaust. Not really thick, but its noticeable. SO whats wrong?
I think the MAP sensor may be bad? what else could it be?

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Yo, for everybody else: I just got back from Brian Felts home and the car has problems. Everything checks out fine but it just doesn't want to run anything more than idle. He has an MSD ignition but I don't know if that has anything to do with the backfires. It idles great ONLY when the tan "advance" wire is plugged in. If you take it out the car almost instantly dies. It isn't running rich after they (Kyle) switched out the MAP. I checked all the sensors and everything is looking normal. When we got it to idle, it seemed like the IAC wasn't working. I couldn't really check because the darn aldl paper clip trick wasn't working. I swapped out his ecm for mine and still a no go. I can't figure it out. I do know that when we gave it some gas at idle (in gear and in park) the thing almost dies and then it burps a nice big backfire. One time it was so bad that the TB caught on fire (not a scary), not a good thing. It seems to me that the engine isn't getting enough fuel(backfire when given gas). He's running with stock 40lb injectors. One time it was chuging at near 100rpm idle and we couldn't figure it out. Next time I go visit I or Kyle should have the diacom/turbo link stuff to watch everything. Anybody have any sugestions to double check.
I really think it is a fuel problem still. I sugested that they take the TB off (have to since we broke off the TPS sensor screws) and make the fuel pressure adjustable. Once that is done, boast the fuel pressure up real high and see if it gets any better.

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, Jon (350 TBI!)
91 Red My website

[This message has been edited by JPrevost (edited June 09, 2001).]

 

Fuel pressure should be between 13-15 PSIG, and the pump should deliver at least one pint on fifteen seconds to the TBI unit. Remove the line from the filter outlet or the pressure line at the TBI to measure the flow rate of the fuel pump.

Saying there is "plenty of pressure" isn't really describing the situation. Quantitative data is a good thing - define "plenty" in terms of PSI, please.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

There is a fuel pressure guage on the line, we have a new pump and plenty of pressure to the TB, but is it enough at the injectors? That is what JPrevost is getting at.

J thanks for comming to help, when will you have more time this comming week? I can get the cale you need fairly easy, but my Laptop is in Athens, though I have the software for turbolink so we could install it on you laptop if you get it running and I will provide the sopftware and cable.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

You said it was a new motor with a new cam.
Double check to see if your lifters are set correctly.It would only take one intake valve staying slitely open to cause the same thing to happen.(backfire into the manifold)

 

I'd try re-stabbing the distributor. If the motor will only run with the advance wire hooked up it may be firing to soon. If it fires when the intake valve is still open it would cause the backfiring out TB. Just a thought.

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'87 Silverado
350 4 bolt main bore .040 over
TB Injected
Ported and Polished heads
Comp cams 268h cam and top end
Flowtech headers

 

JP's buddies problem sounds like an ignition module problem. IE, spark signal ok with timing set disconnected but not working with ECU control? either ign module or ESC module, my guess... Won't get any error codes for them, either. Just gotta try and replace the ign module or try another known good distributor from buddies car.

Other guy = MAP is my best bet but I guearantee there are error codes if you scan the ECU with a paperclip...

 

Ok new Ignition module so thats not it. I know its not firing at the wrong time because it will idle fine and sometimes with the plug disconnected. I think its fuel related so if we can get to the point where we no its not that then we might move onto the other sudgestions. I think maybe the back fire might be to detonation whiole the intake valve is open and then igniting the fuel in the intake manifold maybe? I dunno because it didnt do it until it was a little warm.
We will figure it out soon I am sure



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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Whats the odds of the new module being bad.......Its a wells from AutoZone.


Brian


PS Thanks Jon!!!!!!!!!! Come down anytime I will share any tools you need



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1989 Camaro RS

305 .030 over Hydro Pistons
Vortech heads milled to 58cc...Performer RPM intake....LT4 cam..Crane Gold rockers...FastChip custom chip...ALum. Driveshaft...3.73 gears with Posi...underdrive pullys...Rebuilt 700R4 with Vette Servo and B&M shift Kit...MSD ignition...A/C Delete No SMOG junk....1997 SS leather interior...B&M Shifter... Ultimate TBI mods...14X3 K&N open Element Non-Drop...Hooker headers....3" exhaust with Flowmaster Cross flow 16X8 Wheels from 97 RS Spohn LCA's Spohn Panhard Bar..LETS PLAY FORD!!

 

I have a problem with my 89 firebird formula 305 engine. The idle shifts up and down and sometimes it backfires. I've checked spark plug wires, distributor, spark plugs, throttle position sensor, knock sensor, iac sensor, coolant sensor, corrected timing, rebuilt throttle body, and checked all vacuum lines. Do not think it is the map sensor or the egr valve. If anyone has any suggestions, please let me know.

 

this thread is almost 10 years old...... you should start a new thread.... but it does sound like an EGR problem, i would replace that and the pcv valve, if that didn't do the fix i would suggest inspecting the injectors/ fuel pump pressure