87 V10 5.7 Runnin rough

[CSFJ]

I certainly agree with the fuel volume issue too since it really mimics a fuel starvation problem. If it were a carbed engine, I'd be going directly for the accelerator pump. Reason I say that is because you mention mashing the gas and it falls flat on its face, then let up and it recovers.

Dumb Question, and not even sure it can be done, cuz I don't recall if the threads are different on both end or not, but you mention you replaced the fuel filter recently. Is it possible you may installed the fuel filter backwards? It would make sense to me that if the paper collapsed in the filter, it could still push the pressure but restrict the fuel volume. Did the old fuel filter seem to be restricted at all?

If I remember correctly, those filters have the same threads on both ends.

 

[PrairieDrifter]

I think they are the same threads also, not completely sure. To me your situation screams fuel starvation.

That hose inside the tank can also cause fuel leak down which would normally cause extended cranking, so you can kind of tell if that's your problem or not sometimes not

 

[Jims86]

Foamy Nailed it!
The tune is the problem most likely. I would recommend an adjustable regulator and 14psi.
Contact Eldon at Wester's Garage in Canada, he may have a tune loaded and ready to go...at least I expect he would, as Vortec heads are a popular swap. The only alternative, which is labor extensive, is to get harness and PCM from a 94-95 gmt400, and get chip code BNKM which was used in the 96 1 ton van with the factory TBI Vortec. The advantage to this mis you can use this setup if you wanted to install a stronger E transmission, like a 4l60E or better, 4l80E.
And just an FYI, the tear in the in tank line will affect it regardless of fuel level...it ends up just pissing the fuel back into the tank, and drastically reducing pressure.

 

[HotRodPC]

Just seems to me the few times someone struggled with lack of fuel related symptoms, after all was checked and nothing could be found wrong, eventually it was found to be either that split line on the fuel pump or the EGR valve. Hopefully 89S or Jim will drop in shortly. It'll end up being one of those simple things and we'll all be, Why didn't I think of it?

 

[HotRodPC]

OH, and speak of the Devil. There's Jim. Thanks for dropping in !!!

 

[HotRodPC]

Foamy Nailed it!
The tune is the problem most likely. I would recommend an adjustable regulator and 14psi.
Contact Eldon at Wester's Garage in Canada, he may have a tune loaded and ready to go...at least I expect he would, as Vortec heads are a popular swap. The only alternative, which is labor extensive, is to get harness and PCM from a 94-95 gmt400, and get chip code BNKM which was used in the 96 1 ton van with the factory TBI Vortec. The advantage to this mis you can use this setup if you wanted to install a stronger E transmission, like a 4l60E or better, 4l80E.
And just an FYI, the tear in the in tank line will affect it regardless of fuel level...it ends up just pissing the fuel back into the tank, and drastically reducing pressure.

So then if he has 12psi, it's not likely a split fuel line in the tank?

 

[Jims86]

Just seems to me the few times someone struggled with lack of fuel related symptoms, after all was checked and nothing could be found wrong, eventually it was found to be either that split line on the fuel pump or the EGR valve. Hopefully 89S or Jim will drop in shortly. It'll end up being one of those simple things and we'll all be, Why didn't I think of it?

Nope, at this point, that stuff doesn't matter...the fact that he has vortec heads without the proper tune is the big ticket issue...probably didn't install EGR Anyway.

So then if he has 12psi, it's not likely a split fuel line in the tank?

Correct. Split hoses usually bring the pressure down to carb spec..8 and under

 

[HotRodPC]

I'd have thought a tune would only improve performance to take advantage of the Vortec heads, but not hurt the driveability and have a negative impact. So would it be wise and is it possible for him to get a Big Block TBI unit that should also have a higher CFM rating and bigger injectors that would closer match the CFM of the Vortec heads before he got the tune and get it all tuned together at the same time?

 

[Bain1012]

The egr isn't installed. Been really busy lately haven't been able to run any tests other than the fuel pressure. I'm leaning towards what Jims86 said especially since my whole top end has been port/polished and port matched together. But the last thing I can't wrap my head around is it will occasionally drive and pull the way it has been built to do.

 

[Bain1012]

I would go carbureted but I just do too much cross country driving and elevation change.

 

[PrairieDrifter]

I can't remember but I thought it wasn't a very good idea to polish the intake ports on the heads for a tbi? The rough surface is better for the air and fuel to mix giving you a good mixture and if you polish it takes away that roughness and the gas tends to separate from the air. I think it was for tbi cuz port injection doesn't matter because the fuel is sprayed right on the intake valve and it doesn't have to mix in the intake manifold itself.
Just brainstorming!

 

[CSFJ]

I can't remember but I thought it wasn't a very good idea to polish the intake ports on the heads for a tbi? The rough surface is better for the air and fuel to mix giving you a good mixture and if you polish it takes away that roughness and the gas tends to separate from the air. I think it was for tbi cuz port injection doesn't matter because the fuel is sprayed right on the intake valve and it doesn't have to mix in the intake manifold itself.
Just brainstorming!

I think the same applies to carbs too. Want just enough roughness to atomize properly.

 

[PrairieDrifter]

I think the same applies to carbs too. Want just enough roughness to atomize properly.

Yep if the fuel and air mix in the intake you need that roughness, that's why port injection doesn't apply to that rule. You can polish your exhaust ports and manifolds or headers, but you shouldn't really do the intake ports because you want the best mixture you can get.

 

[HotRodPC]

I would go carbureted but I just do too much cross country driving and elevation change.

Nawww, don't go Carb. Best to work the bugs out of the TBI. As you mention, elevation changes, another good reason. Everyone wants to escape issues and go the easy way out and end up Carbing their trucks, but Computer Controlled and injection even if it is just TBI, is really the way to go for efficiency. Pro's and Con's to both but there's more Pro's to the TBI in this case IMO.

 

[Bain1012]

I've built plenty of carb/tbi engines for drags/bogging with the head mech at H&N Motorsports and have never had any complaints about the porting or polishing causing issues.