So I have a 1994 chevy g30 HD 7.4lt 454 big block sometimes it will barley start and others is starts right up but whenever I in reverse or drive if I push more than like an inch down on the gas peddle it will start to stall it is tbi and have replaced tbi gasket tb position sensor idle air motor fuel pump and fuel filter still nothing then a ship said I might have a clogged catalytic converter so I cut it off and straight piped it still same problem just don't know where to go from here
Yeah I changed that last week I don't think it's a fuel problem cause if it's in park or neutral I can Rev the engine just like normal it only happens when there's a load on the engine also have tried spraying fuel from a bottle into the carburetor while it was stalling out and it didn't help what do you think about it being torque converter that's what one of my friends thinks it might be cause the fact it only happens with a load on the transmission I'm really torn on what to do I could just put a torque converter in it but that's basically all my money and this vehicle is a converterted box truck that I made an rv that I live in now I'm an extra 2hrs away from where I normally park and nobody seems to be able to figure it out without just replacing the part
Change the fuel filter and if that doesn't work pressure test the fuel pump a weak fuel pump will often do that. If not that it probably needs new injectors
Yeah I changed that last week I don't think it's a fuel problem cause if it's in park or neutral I can Rev the engine just like normal it only happens when there's a load on the engine also have tried spraying fuel from a bottle into the carburetor while it was stalling out and it didn't help what do you think about it being torque converter that's what one of my friends thinks it might be cause the fact it only happens with a load on the transmission
So iv posted this before this was my last post (
So I have a 1994 chevy g30 HD 7.4lt 454 big block sometimes it will barley start and others is starts right up but whenever I in reverse or drive if I push more than like an inch down on the gas peddle it will start to stall it is tbi and have replaced tbi gasket tb position sensor idle air motor fuel pump and fuel filter still nothing then a ship said I might have a clogged catalytic converter so I cut it off and straight piped it still same problem just don't know where to go from here
) since then I had an auto shop replace my torque converter and still having the same problem they have tested my egr valve , ignition timing , fuel system and literally everything they could think of and still don't know what's wrong I'm at such a loss with this and I really need it fixed cause it's a cutaway box truck I converter to an rv and is my home any ideas would be greatly appreciated
Hard to say since they've tested "literally everything they could think of".
Sounds like a fuel starvation issue but we have to assume one of your mechanics put a fuel pressure gauge on it. So that rules out a bad fuel pump or a clogged fuel filter.
They must have checked the injectors too.
Since the truck is almost 30 years old they should have done a compression test on it also.
We have to assume they did all this stuff.
Yet it still seems like a fuel starvation issue under load and the one thing you didn't mention was if anyone thought about the faulty MAP sensor or its vacuum hose having a small leak.
On yours, in acceleration mode the ECM looks at rapid changes in throttle position (TPS) and manifold pressure (MAP sensor) and provides extra fuel.
The manifold pressure changes much more rapidly under a No Load acceleration as opposed to a Load acceleration.
Of course if the issue was severe enough you'd expect to see a code 32, 33, or 34, on yours but what if it wasn't severe enough to trip a code?
Just something to consider.
One more thing. Before you do something as drastic as cutting out your cat again check into the forum and float the idea past us.
You could have bought a $20 exhaust back pressure gauge and within 10 minutes determined if you had a clogged cat.
I'll talk to them about the map sensor they have been looking for a vacuum leak and haven't found anything what do you think about my actual ecm crapping out? Just an idea iv been thinking about just don't know how to test it iv got no check engine light or codes as far as I know he told me when he hooked a scan tool up it wasn't really helpful
They tried putting a new map sensor in and it didn't help iv got a new ecm on the way and they said if it's not that then next steps would be to look inside the actual engine and see if something in there is clogged or broken
Did the testing include data analysis with a Tech2 scan tool (GM factory diagnostic tool for that vintage)? That might give some clues as to what's going on.
