When running at high elevation 4000ft up she runs rich.

Is it just running rich at 7000' — or as actually compared to lower/sea level? How much change from what altitude to 7000'? Whether it is a barometric correction or tuning issue, I can't say yet.

EFI is awesome for this type of stuff, as it can be set-up and adjusted much easier than carbs to squeak just the right fuel with just the right timing (required to take advantage of the fuel tuning!), for different conditions and loads. Need more info, your tune and logs. Your usual general global location would also be helpful for possible tuning references.

 

The PO set it up for running at sea level.
He drove it from Lompoc on the coast to the Calif central valley pulling his drag boat.
I am at 1600 ft and drive up to 6000ft on my local camping trips.
I have a camera mounted on the pass side and can see the exhaust pipe.
When pulling long grades up the hill I can see the slight dark exhaust coming out indicating running rich.
Also have had family following me said they could smell the exhaust.

 

Do you have your handheld or add-on tablet for the Sniper 2? I'm looking for numbers, and logs would be best, but actual data readings (e.g., AFR, MAP, fuel pressure, etc) from 1600 to 6000 feet would tell us if it's a barometric issue, or a tuning issue. I don't want to assume the issue until we know if there's a problem and where it's coming-from.

 

I do not have a sniper 2 installed just asking questions.
After looking at the Holley Sniper 2 forum there are a lot of people have problems with the system.
It is not as reliable as one would think from all the hype.

 

Have not had hands-on experience with Holley TBI, but EFI tuning can easily be come a overwhelming (Frustrating..!) learning curve at first. Just saying.. some of what you’re reading could be operator too.

I’m sure with your carburetor and going through a little bit of a learning curve tuning it (the way you have been watching the vacuum gauge— just in memory, you’re 1/3 of the way there already. And then along with getting the ignition timing (Distributor) dial in, I would say 10 mpg is in the bag.

 

+1, ▶ all the concepts and principles of fuel and ignition tuning are identical from carbs and mechanical distributors to digital. ◀ This made my transition from one to the other much easier. I found digital is overall easier, as the functions are more clearly separated on fully-tunable EFI (analog carbs and tend to blur functions together), while digital sensor feedback is a huge advantage for what it likes and responds-to, while finally it's much easier and quicker to click a change than pull the carb or distributor apart for one change to test.

I can log or tweak on any start or drive to the grocery, in nice clothes, from the driver's seat. I can test several successive changes in a fraction of the time, yielding a better result. This is big. I can do a change on a carb and say that's 'better' or not. I can do 5 comparative changes on EFI and pick #4 as best. I've done decades of both, and carbs are cool and effective, while digital is just improvements on them. 🤷‍♂️

If you don't already have tuning skills, EFI can make learning the fundamentals much easier, with the separation of function and instant feedback of any change. Moving to carbs from there is learning what functions blend together in a carb to get the same results (this change also affects that and another thing).

Likewise, from carbs is simpler but feels awkward, that this one function is now separated into these other three. Neither direction is difficult, as the concepts and principles are the same, and it's just how you're getting there.

 

After spending time on the Holley Sniper Forum I came to the conclusion that the system is just not reliable enough for my needs.
A failure out in the boonies would lead to a very expensive tow bill.
I have decided to go with the Edlebrock carb that will allow me ease of jet changes on the road vs Holley take the carb off.
That way I can lean it out when driving at 7000ft plus altitudes during the summer then richen it back up in the fall when I head home.

 

I've run a sniper for about 5 years. In general, the sniper product is decent quality, and there are a ton on the road. The forums are mostly all problems. No one reports nothing wrong.

That said they do not conform to SAE OEM quality levels (zero defect) and parts are not available at any local parts store.

I had one injector quit 150 miles from home. long tow. I carry a spare set, an 02 sensor, and a regulator diaphragm.

Carbs have limitations and for the type of hardcore offroading I do, they are a hard fail.

The only better option in my opinion is a complete 7.3 Godzilla.

 

That said they do not conform to SAE OEM quality levels (zero defect) and parts are not available at any local parts store.

I had one injector quit 150 miles from home. long tow. I carry a spare set, an 02 sensor, and a regulator diaphragm.

Exactly I would not trust the system.
At least with a carb I can do a road side repair.
Wont be doing any off roading in a 26ft rv, just forest service roads.

Ul

 

Not to pop your bubble, but reshape it. These forums and many others are full of primarily mechanical and support hardware failures that are far more common. Carb or EFI failures are rarely the "EFI" or "carb". Just a reality check that a "carb" repair is 99% not a screwdriver on the road-side, though people like to hope so, that they will know exactly what to do if the time comes, and will have the parts and tools to do it without an air-drop.

I'm not saying you're screwed. I'm saying you have to look at the entire package and prep it for reliability, in any form. I have done this with real-world African and SoAm safari trucks. Carbs or EFI, carry spares or whatever you need for in-field service. Everything else is supporting hardware, and the most common area to get sloppy for 'failures'.

Treat it like a passenger airliner and enjoy the same reliability. Always tow a backup vehicle, or take a buddy rig. Safaris never go far solo, only in pairs or more, or have at least a dirt bike or other emergency backup. It's exciting to free-climb, but if you don't want to fall use a rope, relax, and enjoy. Choose every supporting component and its installation for optimal goal coordination and reliability. Drive happy.