What bin to start with?

[eagle mark]

Well your not supposed to go above 100 but if you add VE Main and VE adder in STOCK 1227747 they are above 100...

Suposedly they go static, never close, but they already do that from factory? There's a conversation about it going on including BPW and fooling ECM at other site.

When this happens when I tune I raise fuel pressure and start tuning.

Is this only happening WOT? Have you tried adding some PE?

 

[Mastiff]

The two tables together exceed 100 all over the place right now. I can't believe the injectors go static just because the VE is 100% though. That would mean GM put in no design margin at all. I think VE of 100 means that the engine is operating at 100% efficiency with regard to its displacement. I have two potential problems: first is that I'm not tuning like I think if the computer truncates VE over 100 to exactly 100, second is that VE over 100 would seem to indicate some other problem in the parameters since it shouldn't be theoretically possible if the BPW is set right.

I'm working on my fuel pressure now. I need to figure out how to be able to see the fuel pressure while driving. I have an underhood gauge, but that only tells me things are fine at idle. My fuel filter also looks pretty bad, so I'm replacing that in case that's causing a restriction.

 

[dave w]

I often combine both the VE 1 and VE 2 tables, then ZERO the VE 2 table on the 7747 ECM. Other ECM's like the 1228747 do not have a VE 2 table. I often have to adjust the BPW for engine modifications like an aftermarket camshaft, aftermarket headers, dual exhaust system, aftermarket intake manifold, aftermarket heads, and displacement increase to a 383 cubic inches. A BPW of 140 ~ 145 (stock fuel pressure) is not uncommon for an engine with modifications like I described.

dave w

 

[Mastiff]

Do you also zero the 0 RPM entry in VE2? I understand that the VE2 entries are added to the last RPM data in VE1 to fill in the higher RPMs. I assume its the same kind of thing for RPM 0, but I'm not sure.

 

[dave w]

Do you also zero the 0 RPM entry in VE2? I understand that the VE2 entries are added to the last RPM data in VE1 to fill in the higher RPMs. I assume its the same kind of thing for RPM 0, but I'm not sure.

Here is a sample of VE1 + VE2. Most of the VE numbers are between low 40's and mid 90's. I think something like this will help, once the BPW is set to a new value.

dave w

 

[Mastiff]

140-145 doesn't really seem like much. My initial tune had BLM values around 150 which is about 17% more than stock. If you tried to absorb that all with BPW, you'd be up to 158 (my bin starts with 135). And this is basically where I'm headed since ARJT starts with VE1+VE2 greater than 100 already. I have no headroom there at all.

Maybe I'll get lucky and the fuel filter will explain everything, but I'm not holding my breath.

 

[dave w]

140-145 doesn't really seem like much. My initial tune had BLM values around 150 which is about 17% more than stock. If you tried to absorb that all with BPW, you'd be up to 158 (my bin starts with 135). And this is basically where I'm headed since ARJT starts with VE1+VE2 greater than 100 already. I have no headroom there at all.

Maybe I'll get lucky and the fuel filter will explain everything, but I'm not holding my breath.

Personally, I've not needed to go much above BPW of 150. I personally would install a higher pressure spring and an adjustable pressure regulator when going above BPW of 150. The 4.3 V6 typically has a BPW of 181 or so.

I sometimes will attempt to "Bookend" a BPW by programming a value that should send all the BLM's rich. I think it's worth considering a BPW of 160 just to make sure all the BLM's go rich. Once all the BLM's are rich, then the "Bookend" is known so going any higher in BPW is not needed. Who said black smoke was a bad thing?

dave w

 

[Mastiff]

Okay, so I had the BPW up to 170 and the thing still wants more. This is after replacing the fuel filter. I must have a fuel problem. What do you consider normal fuel pressure on these systems? My gauge is showing 10 at idle. I thought I had 15 before, but I can't be totally sure.

The big thing (maybe) is I went and looked at the filter I just put in while the engine was running and the thing is full of air, just frothing and circulating around in there. I can't tell if it's drawing it in or if it's just trapper air. Either way I'm not liking it. Is there something wrong with this setup?

 

[eagle mark]

I've run that pump with a filter before it at least 30 times in person and know of 100's of others with no issues. 10 PSI is not enough on an accurate gauge!

If when it's running you see air bubbles circulating, not just a bubble on top, then you have a loose connection somewhere from the filter to the tank and it is sucking air!

Since everyone is told to run 3/8th line from tank to TBI unit and the stock fuel tank on a carb truck is 5/16ths this is probably where your issue is.

If you have not taken out the tank and cleaned the sock on bottom of pickup tube, or replaced, I remove them because I run the filter before pump. It will cause a severe suction and can collapse hose!

Rule for pump is below bottom of tank. That is false. If you read the instructions on that TBI in line fuel pump it can be mounted 2 feet above tank. Lower is better. Their is also an identical looking pump for TPI. One id PN5000 one PN5001

EDIT: If that is your ground wire to fuel pump I see it also needs to be put at least to good clean conection on frame and frame needs to be grounded to engine and engine needs to be grounded to body. These are always EFI conversion issues. I run a ground wire from pump to block.

 

[Mastiff]

I like the parallel conversations on multiple boards. Anyway, I considered that it could be sucking air. The clamp is pretty tight on the filter. Maybe I'll snug it a little with everything running and see if I can see any difference in the bubbles. The next interface is at the sender which might be tough to access.

I do need to drop the tank soon because the sender for the level gauge is shot. But if I go to that trouble I'm tempted to use an in-tank submersible and be done with this crap.

 

[dave w]

I like the parallel conversations on multiple boards. Anyway, I considered that it could be sucking air. The clamp is pretty tight on the filter. Maybe I'll snug it a little with everything running and see if I can see any difference in the bubbles. The next interface is at the sender which might be tough to access.

I do need to drop the tank soon because the sender for the level gauge is shot. But if I go to that trouble I'm tempted to use an in-tank submersible and be done with this crap.

I like in tank fuel pumps! Nothing wrong with frame mounted pumps. I just like in tanks pumps best.

dave w