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Back to carb?

Mastiff

Mastiff

1/2 ton status
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Jul 21, 2002
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Tucson, AZ
How weird would it be to undo my TBI conversion and go back to carb? I like to go up to a shooting spot in the boonies and I'm paranoid about the ancient electronics and wiring and all the points of failure (pump, computer, module, etc.). I've had various minor failures in the past few years, none major, but nothing I'd want to figure out away from home. It might be fun to simplify. But I do have the vague memories of hard starts and choke issues and all the rest...
 
I would think that the heat of Tuscon would be the biggest factor to sway you away from going back. Yes, you could run a cooler T stat, but I don't see how you could get a small block to run under 200* in that heat if you aren't moving at a decent pace to keep the airflow up enough.
I would carry a complete spare TBI system rather than go back to a carb. I know that you are looking at the simplicity, but I never had tons of problems with the 3 different TBI trucks that I had. Only after I swapped cylinder heads and installed very short headers, did I have any problems with my '90. One friend and I couldn't hear the exhaust leak without a stethoscope, so I made the choice to go away from TBI. This was poor diagnosis on my part.
 
Mastiff said:
How weird would it be to undo my TBI conversion and go back to carb? I like to go up to a shooting spot in the boonies and I'm paranoid about the ancient electronics and wiring and all the points of failure (pump, computer, module, etc.). I've had various minor failures in the past few years, none major, but nothing I'd want to figure out away from home. It might be fun to simplify. But I do have the vague memories of hard starts and choke issues and all the rest...
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Just do a full tune up, including replacing common sensors that may fail. Then l, carry spares if needed. The TBI is no more or less reliable than a Quadrajet was. It all just requires maintenance.
 
@Mastiff do I remember it correctly that you have a different distributor than a normal TBI? I ask because I carried a complete distributor and coil, ECM, fuel pump, strainer and filter, plus some sensors. I never needed them.
It would be just a little more space to carry a complete throttle body, rather than spare injectors and regulator. Keeping some parts clean and free of damage from shaking all over can be a challenge.

Not really disagreeing with Kenny's idea because the old days made it a good practice, but I personally wouldn't replace many sensors due to the concerns that quality of replacement parts isn't what it used to be. I have been seeing this more lately. ($430 Cummins solenoid that was bad out of the box, was one example last week. ) I would just carry spares and hope the best.

Some may say "If it's not broke, don't fix it."

Cap, rotor wires and plugs, sure. Keep the old plug wires for spares if they are good.
 
All said and done in my time with efi swap ......... i miss my tbi on my ol truck . . It just worked .

Only way anymore if i swap is a gm 8.1L swap and standalone it and run it . Screw aftermarket for 95-98% of us .
 
kennyw said:
Just do a full tune up, including replacing common sensors that may fail. Then l, carry spares if needed. The TBI is no more or less reliable than a Quadrajet was. It all just requires maintenance.
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Spares could make sense. For me I have a EBL modified computer so that would be a big expense, plus getting it set up and programmed the same way. Spare module, spare relays, spare fuel pump? Not so worried about sensors since the truck will at least run without most of them I think. Fuel pump is no point because I'd walk ten miles before trying to drop the tank in the field.

It's a psychological thing I think. There are so many damn wires and relays and fuses and I don't remember what they all do. When it stops I'm immediately online scrounging for wiring diagrams and trying to remember about oil pressure switches. A carb with a mechanical fuel pump is easy to understand and I don't think things tend to fail abruptly so that the whole thing is a brick. The carb vehicle still has the module, but I can carry one of those and it's easy to replace.

The really simple one was the 6.2L diesel on my CUCV. One wire to the whole engine. I'd contemplate swapping one of those in but I think it'd be $10K+ before it was done.
 
I vote stick with the TBI. The EFI and electronic parts boogeymen came from the late 80’s and early 90’s when the technology was new and everyone knew how to work on a carb.
I’d spend the carb money on getting the tbi unit rebushed and put all nex gaskets in, a vortec fuel pump and call it a day.
Tbi works great in stock form, when modifying an engine its not the best.
 
Imo, long term the OE TBI is much more stable and dependable than aftermarket EFI kit (especially those with the ECM in/on the TBI).

@Mastiff are you good at working on carbs? No point in swapping for simplicity if you struggle with working on it (not that they have dependability issues).
 
I'm not great at carbs, but once it's set up it ought to work for a while, and I expect when it starts needing adjustment it doesn't just abruptly leave you stranded. I never had that when I had a carb. I did have hard starts cold and carb icing when I lived in Iowa. And it ran like sh*t when I drove to high altitude in Colorado.

I wish it was easier and cheaper to swap a 4BT.
 
Fear of parts failure is real. Best you can do is figure out your own worst case scenario and plan for that within reason.

If you go camping off grid 2-3 times a year and your worst case scenario means hiking ten miles for cell reception, you should invest in a Garmin unit and a data plan so you can make that emergency phone call and get a tow truck en route or a buddy on the way with some spare parts.

If your worst case scenario is breaking down on the highway, that's just inconvenient most of the time and the cost of a tow isn't going to exceed the cost of all those 'just in case' spare parts that you want to buy and leave rattling around in a trunk. Better off playing your odds and knowing a tow bill might come some day.

In all cases, keep some water, flashlights, and basic tools in the car. Calm your mind by knowing that you aren't going to suffer any great hardship. Life is sucks sometimes and the only way to to be 100% certain you are never left stranded with no help is to trailer another running vehicle with you everywhere, which is also 100% impractical.

All that being said, keep running what you've got unless the vehicle simply isn't reliable at all. Find out what the cost might be to get a tow from that shooting spot in the boonies and compare that to the cost of a carb and all the headaches that come with tuning it. They aren't exactly cheap these days.
 
My worst case scenario is breaking down where a tow truck can't go. Hike out to reception and beg strangers on Facebook to drive out and tow me and possible have my truck ransacked while I'm gone... I have a long standing question in my mind about how to get out of such a situation.
 
I wouldn't swap, at all.

The fact that TBI works as well as it does, is reason enough to leave it be. A failure is an unknown. You don't know if, when, or where something will fail. But that's true of everything. Axle bearings. Piston. Water pump. Alternator. And keep going. Any of those could fail at any time, any place, and leave you stranded.

Driveability is 100% of the time you are using the vehicle however. Go look at how many "my carb doesn't run right" posts there are. They are not foolproof devices. EFI is a better driving experience. Hot, cold, hills, you name it.

In 29 years of owning/driving these trucks I've had a mechanical fuel pump fail and strand me, I've had a carb fail (only reason it didn't strand me was because I could get the truck pointed downhill), I had a pickup coil fail and strand me, and twice Ive needed a tow for what I believe was a counterfeit electric fuel pump (resolved by putting the 20 year old original back in).

I've been running GM EFI for roughly twenty of those 29 years. So twice as much time and the same number of failures. I'm running the same parts that came with the 1988 EFI, that I acquired 20 years ago when I put it in the truck, or have been replaced due to the mentioned failures. Ok, heated O2 sensor as I thought I needed it as an improvement lol.

I just can't see going backwards to get worse driving performance pretty much all the time you use the truck, and really not solve any of the "I'm stranded and there is no way I'm driving this thing out" problems. Carry a spare of everything that fits in a decent sized box, and call it good. All you have to remember is spark and fuel. Then start swapping spares.

Heck, couple years back I had my water pump/alternator belt snap randomly on me in the woods. I didn't know it had happened. I figured out something was wrong in time, but I likely wouldn't have made it out without that simple spare!
 
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I'd opine there is a cutoff point where needing a tow truck and a tow truck not being able to get there is when you need to be towing your toys to the trail and always having more than one vehicle out on the trail in case you need to get towed back to the trailer. And you absolutely need that GPS device in that scenario. A Garmin unit and a data plan costs less than a big mud tire.

I have all these same fears about my '22 GMC pickup. I take the whole family camping in it and it has never let me down. But I always have my Garmin and a jump pack with a tire pump just in case. If it's anything other than a dead battery or a second flat tire, there ain't a damn thing I can do about it but call for help.

It sounds odd, but you can always call some local tow shops and ask what their limits are. In a place as big as Tucson, i'd imagine there is some shop that has a trail worthy tow truck. Find them and keep the number handy

Technology makes cars more reliable but harder (or impossible) to fix on the trail. Pick your poison.
 
You guys all make fair points. Nobody has chimed in in favor of the swap. It would be kind of fun as a project though...

The big unknown in my mind is the computer. It's 35 years old or so. So far so good I guess and I haven't read many accounts of them failing. Getting a spare would be very expensive since I have EBL, and I don't even remember how to program it. One option would be to make the truck work with a fully factory ECM, but my existing one has some emissions stuff and VSS deleted, plus it runs the electric fans.
 
Mastiff said:
The big unknown in my mind is the computer. It's 35 years old or so. So far so good I guess and I haven't read many accounts of them failing. Getting a spare would be very expensive since I have EBL, and I don't even remember how to program it. One option would be to make the truck work with a fully factory ECM, but my existing one has some emissions stuff and VSS deleted, plus it runs the electric fans.
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How much is a new carb, and how much is EBL?
 
Mastiff said:
EBL is $500 and then into the emergency kit never to be seen again. But good point.
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*Hopefully* never to be seen again. Lol

I know some have seen ECM failures, and I know they can happen, but as problems go, these ECMs are pretty darn robust.

Compared with modern vehicle PCM's, BCM's, etc., our ECM's are as antiquated as a carburetor. But that means simple, and a lot less to fail in general. Less components, less heat, less connections, and so on and so on.

I think you can probably look at the OBD1 ECM's like refrigerators from the 1950's. They were new at the time, and the manufacturers had no use history to draw from, so they are what we would consider overbuilt by today's standards, because they didn't have a clue how long they would last, or would need to last. Yes, they don't do things as efficiently, or quickly, or as well as more modern designs, but they last forever.

Nowadays we've been conditioned to pay $25-100k for a vehicle, and have problems right away. Or home appliances having a lifespan of 5 years. It didn't used to be that way, and I think the complexity of modern systems is the reason. There is just far more to fail, so there will be more failures. Your TBI ECM has (basically) one job: run the engine. And fans apparently. :)
 
Mastiff said:
Spares could make sense. For me I have a EBL modified computer so that would be a big expense, plus getting it set up and programmed the same way. Spare module, spare relays, spare fuel pump? Not so worried about sensors since the truck will at least run without most of them I think. Fuel pump is no point because I'd walk ten miles before trying to drop the tank in the field.

It's a psychological thing I think. There are so many damn wires and relays and fuses and I don't remember what they all do. When it stops I'm immediately online scrounging for wiring diagrams and trying to remember about oil pressure switches. A carb with a mechanical fuel pump is easy to understand and I don't think things tend to fail abruptly so that the whole thing is a brick. The carb vehicle still has the module, but I can carry one of those and it's easy to replace.

The really simple one was the 6.2L diesel on my CUCV. One wire to the whole engine. I'd contemplate swapping one of those in but I think it'd be $10K+ before it was done.
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As far as the in-take pump. Most guys put an access panel in the rear floor board. This allows you to put in a new pump, without pulling the tank, and/or skid plate! Makes it a 20 minute job, to diagnose, and/or replace the pump!
 
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