At my wits end.. Looking for any idea.

[bobby v]

Way too far but thanks anyways. FYI its a 90 SS454 with 700R4 tranny, ECM I have no idea what it is. I'll screw with it till its right or find someone who can I hope.
Limited resources up here and most guys that I talk to sort of turn their nose away when I say its TBI
Bobby V

 

[Schurkey]

its a 90 SS454 with 700R4 tranny,

Wouldn't that truck have come with a TH400?

What other mods have been made?

 

[PlayingWithTBI]

I'll screw with it till its right or find someone who can I hope.

See if you can find someone with a scanner, it'll hopefully save you a lot of time and money. Good luck with it.

 

[89GMCJOHN]

I don't have a Camaro wire harness diagram, but typical GM practice is to power the fuel pump via the fuel pump relay AND the oil pressure switch in normal operation. The oil pressure switch can turn the pump on, but it can't turn the pump off unless the fuel pump relay or relay wire harness is defective.

If fixing the oil pressure switch made the vehicle run better...I bet the fuel pump relay was cooked.[/QUOTE]

The fuel pump relay and oil pressure switch were in PARALLEL in the Camaro as I recall ... as soon as I cranked it enough times to get around 4-6 psi up in the oil galleys the oil pressure switch closed and completed the circuit finally enabling the fuel pump around the flakey fuel pump relay ( one would just think it is a hard start problem) when in reality your driving around with a bad fuel pump relay and running off the oil pressure switch and experiencing hard starts ..... lose the oil pump switch going down the road one night as I did and your stranded and have an $86 tow bill home....ask me how I know .

 

[Shane Dyer]

Alright fellas, to give yall an update. I checked all the grounds. All of them were solid with the battery voltage. Checked EGR (also changed it from donor vehicle.) No difference. Checked MAP sensor voltage with vaccum, all is well there. Unplugged o2 sensor, no change in vehicle operation but did set a check engine code. So I would be under the assumption that's working as it should. Checked coolant temp sensor resistance. (Well within range for temp). Checked the voltage for the coolant temp sensor shows supplied 5v. Looks like a scan cable is in the works to see what exactly it's doing.

To answer, this happens cold or hot. My previous response of smooth as butter warmed up was with the MAP sensor unplugged.

Changed ECM with one out of a another truck no difference.


If anyone else has any other ideas at this point. I'll take it. Other than that looks like an ALDL cable is going to be ordered here and see what its saying or doing.

Figured I'd keep you guys in the loop.
Thanks.

 

[bobby v]

Shurkey yes its been swapped (tranny), motor is not oem although it is a SS454 truck but not true to its core, been modded with color, saved tailgate, rollpan, color matched trims, dropped, Cowl hood, Tires & Wheels, interior is stock with oem seats recovered with different materials. and of course the smog equip. is gone
Bobby V

Wouldn't that truck have come with a TH400?

What other mods have been made?

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[alpinecrick]

Now here is the fun part. A couple of weeks after replacing the o2 sensor, I was leaving work, started the truck as normal, and about a minute or so later, truck dies. Cranks, but no start. Waited a few minutes, truck started back up and ran like it normally does. Didn't think to terribly much about it. However, yesterday. Was driving it home from work, was working like normal, then just dies again. Okay... odd. Try to start it, cranks, but thats it. Checked fuel pump fuse, checked distributor wires, checked all sensors were plugged in. Nothing. I walk a little over a mile back home, grabbed some starting fluid and drove back to the truck. Got in it before doing anything, truck starts... dies 30 seconds later. Start it again, i'm able to rev it fine, as soon as it goes back to idle, dies again. Wouldn't start again after that. Tried starting fluid, it fires but immediatley dies again. Left it for about 10 minutes, (checking my phone for ideas) try starting it again and it runs and gets all the way back home and hasn't died like that again.

When my '91 did that it was the ignition control module on the distributor.

 

[Shane Dyer]

When my '91 did that it was the ignition control module on the distributor.

It seems that way, however I changed that and it runs the same. Plus I would think if its ignition based then pulling the map sensor wouldn't have changed. Waiting on tracking for the ALDL cable then I'll post a screenshot if I cant figure it out.

 

[retorq]

Way too far but thanks anyways. FYI its a 90 SS454 with 700R4 tranny, ECM I have no idea what it is. I'll screw with it till its right or find someone who can I hope.
Limited resources up here and most guys that I talk to sort of turn their nose away when I say its TBI
Bobby V

I have a cable and probably the closest guy to you on the forum. What is your truck doing?

 

[RoJo2]

I’m not sure if this would cause your problem but I know from personal experience that these trucks have a fuel prime relay and a fuel run relay. I had an issue with my run relay circuit and could never figure it out so I hardwired a switch into the prime relay and solved the issue. I inadvertently also created a theft deterrent as no one can keep my truck running without knowing where the switch is.

The basic issue was that it would run for about 30 seconds until the prime relay cut off and then it would sporadically run when the run relay kicked in. At the end before running the switch, the run relay would not function at all and I could only run for 30 seconds at a time. Makes for an interesting drive home from 10 miles away on the highway... throw in neutral, crank, put in gear, floor it, die, throw in neutral, crank, put in gear, floor it, die... and so on.

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