87 Chevy 454 TBI In need of desperate help

[tmacpherson]

Little back ground.
I bought a 1987 Chevy V20 pickup with a 454 TBI swap. I drove the truck 2 1/2 hours home and it ran strong and with out issue. My girl even started it first cold just by turning the key that day.

The truck sat for a few days and would not run, it would start up and die. I kept trying to start it and finally got it running. We took it for a test drive around the area and it started sputtering and finally died. cracked it a few times and it finally started went 20 feet and died. Did the same and it started to run strong again. Parked the truck at my house and it has not ran on its own since.

When trying to start the truck it will start very strong for a second or two and just die. When it dies it will sputter air and fuel out the TBI ports.

Here's what I have changed so far and the issue always stays the same.
Spark plugs
Cap and rotor
ICM
CTS
Map sensor and vacuum line
broken gasket under TBI

Here's what I have checked
Its getting fuel in a nice cone shape from both injectors
Its getting spark when I crank it over
Fuel pressure is 12 PSI
It has compression on all 8 cylinders

I'm in desperate need of help since I'm moving on the 10th of Jan and I also need the truck by the 18th.

Thanks for any advice you can give me.

[pontgta]

Check timing and IAC.....


http://67-72chevytrucks.com/vboard/s...d.php?t=515419

This helped me out a ton....

[tmacpherson]

I think timing is part of it since some of my friends have moved it. The IAC has been disconnected and it made no difference but I will try these steps this weekend.

[rfmaster]

Originally Posted by tmacpherson

I think timing is part of it since some of my friends have moved it. The IAC has been disconnected and it made no difference but I will try these steps this weekend.

Do you have functioning SES light? Jumper pins A & B of ALDL connector to read trouble codes (if any).



87 was a first year of the TBI, so it is possible to have factory harness in your truck. I suspect that BBC was swapped in in place of SBC by PO.

Check base timing - should be 0 deg with EST connector open, but this can only be checked once engine is warm and idling normally. Opening EST connector will set code 42 which can cleared by disconnecting battery for 30 seconds (engine off). With EST connector closed idle timing will be bouncing between 17 to 21 deg BTDC - you'll need dial back light to check.

From the looks of it you are describing fuel delivery problems. I would check fuel pump relay and socket mounted on the firewall. It is not uncommon to have a flaky relay or corroded FPRS contacts. An oil pressure switch acts as a safety backup to FPR, but it only closes its contact once oil pressure builds up to about 4 to 6 PSI. For engine starting FPR (fuel pump relay) closes its contacts powering up fuel pump, or after excessive cranking oil pressure builds up forcing oil pressure switch to close. There is FPR relay bypass pig tail - red wire with black spade plug hanging down from FPR socket. Supply +12 to this terminal and fuel pump be running continuously. This allows fuel pressure check without engine running. This way you can rule out FP and fuel filter and get her to fire quickly.

IAC should be connected it allows additional air during cranking. Once you get her to fire and run perform IAC reset. Search this board - procedure has been posted before.

//RF

[tmacpherson]

Fuel pressure is good and FPR looks new swapped with 2nd tank with no difference.

No codes in the computer.

Checked all the connections and grounds that I could see.

Same issue truck fires up and immediately dies.

[meatwagon83]

does it have gas in it?

[tmacpherson]

yes... I've put 10 gallons in it.

[pontgta]

Dis you try the IAC......instructions are in that link i posted previously.....rfmaster..he is the MAN!....those instruction he posted saved me from going crazy...... anyways here they are word for word....

1. Install a jumper wire between Pins A & B of ALDL diagnostic connector.
2. Turn on the ignition (but don't start the engine)
3. Wait 30 seconds.
4. Leave ignition on and disconnect the IAC connector (four wire plug).
5. Remove the jumper wire from the ALDL connector.
6. Start the Engine. The engine probably will run rough and may stall. Just restart and try again.
7. Adjust the throttle stop screw to set the idle to 500 RPM +/- 50 RPM. - stock camshaft!
8. Turn the engine off and reconnect the IAC connector.
9. Turn ignition on and adjust TPS to proper settings. (0.60 - 0.65Vdc at idle is typical, but 0.3 to 0.9Vdc will work)
10. Repeat procedure until the 500 RPM +/- 50 RPM (stock cam) in step 7 can be maintained while TPS is at proper idle setting. Performance camshaft may require higher idle RPM!

Have some on the gas pedal until it idles when the IAC is disconnected.....

[tmacpherson]

The truck has a aftermarket intake and TBI, I don't see a adjustment for the throttle stop or I'm missing it.

[pontgta]

it should have one... I think even the stock tbi have a plug(set at factory)...normally. just remove the plug and adjust . factory ones are located at front right(as u look at it standing in front of the truck). . Take some pics and maybe we can identify it for you




this is factory http://members.shaw.ca/betterthanyou...le/tbiidle.htm

Holley...http://www.holley.com/data/Products/...199R9813-5.pdf

[meatwagon83]

Originally Posted by tmacpherson

yes... I've put 10 gallons in it.

just wondering, easiest things first!

[tmacpherson]

Truck is up and running.

A weak coil finally failed and showed what the problem was. Installed new coil and it fired right up.

I think the timing is still a little off even after I set it to 4 degrees BTDC.
Is there a way to disable the computer to set the base timing before the computer starts adjusting it while I'm trying to set it?

[pontgta]

Originally Posted by tmacpherson

Truck is up and running.

A weak coil finally failed and showed what the problem was. Installed new coil and it fired right up.

I think the timing is still a little off even after I set it to 4 degrees BTDC.
Is there a way to disable the computer to set the base timing before the computer starts adjusting it while I'm trying to set it?

The wire near your firewall should be disconnected to set timming(mine is brown in color). That is what i believe the "computer control"


Gad you found the problem..

[WestButteTruck]

Yes, you need to find your "set timing connector" should be along the firewall, not sure of color on that year, possibly a tan wire with a black stripe by itself and you will see you can dis-connect it. Disconnect, set you timing to 0 and then connect it back.