Beachbum1236 Posted March 16, 2008 Share Posted March 16, 2008 I was out with one of my buddies yesterday, and the battery terminals were loose so i popped the hood so he could adjust them. Whil he was doing it, he noticed that my TBI fuel injection was not actually a Fuel injection setup. He said that it was a pressure carb, which he then said was similar to fuel injection, but instead of the TBI it was setup so the carb pressurized the fuel before entering the engine itself. I have no clue about this type of injection and was just wondering if anyone knew anything about it. thanks Chris Link to comment Share on other sites More sharing options...
Pete M Posted March 17, 2008 Share Posted March 17, 2008 Link to comment Share on other sites More sharing options...
Eagle Posted March 17, 2008 Share Posted March 17, 2008 Your friend is badly misinformed. The '86 4-cylinder IS a throttle-body injection system. Perhaps your friend doesn't understand what "throttle body" injection is, as opposed to "multi-port" injection. You have a single fuel injector mounted in the throttle body. You do NOT have a carburetor. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 17, 2008 Share Posted March 17, 2008 Yeah, send a pic. there were some non-TBI carbed 4-banger MJs built in 1986 for "non-regulated" export markets (the Bahamas may have been one). :eek: Link to comment Share on other sites More sharing options...
LEAD_NOT_FOLLOW Posted March 17, 2008 Share Posted March 17, 2008 The carb'd 2.5L was used in 84-85. It "could" of been a late '85 build and sold as a 1986 model... ;) It's unlikely but it's not impossible... Link to comment Share on other sites More sharing options...
Beachbum1236 Posted March 17, 2008 Author Share Posted March 17, 2008 Well I'm pretty sure he knows what he's talking about, him and his dad were some of the BEST mechanics here on our island and His dad now owns a pretty good sized shop in South Africa, he could although be mistaken, I am not 100% sure. Anyway, here are some pictures, They aren't great and they're kind of blocked by the blue hose, but they're the best I've got on short notice. The bill of sale says that the truck is an 1985, I only have 1986 in my sig because I thought the production models began in 86 and not in 85. I will try to get some more pictures tomorrow, and have them online tomorrow night. Link to comment Share on other sites More sharing options...
jtdesigns Posted March 17, 2008 Share Posted March 17, 2008 Take the intake cap off the TB/carb bore.. Take a shot looking straight down into the piece. I still think its TB injected though. Link to comment Share on other sites More sharing options...
MJ'87 Posted March 17, 2008 Share Posted March 17, 2008 it, TBI. i see a MAP(manifold absolute pressure) sensor, so unless I'm mistaken, a carb wouldnt have one. although, it does look like its missing a lot of electrical that my 87 has. not good enough view to truly tell Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 17, 2008 Share Posted March 17, 2008 Looks carbed w. an air horn, export model or variant. Snap off the air horn and send some more pics. Also did you run the VIN and/or build sheet? Might get some info there. Link to comment Share on other sites More sharing options...
Beachbum1236 Posted March 17, 2008 Author Share Posted March 17, 2008 Looks carbed w. an air horn, export model or variant. Snap off the air horn and send some more pics. Also did you run the VIN and/or build sheet? Might get some info there. not sure how to run the VIN number, but the vin is: 1JTHW6693GT106492 I'll try to find a site than can run it. :cheers: Link to comment Share on other sites More sharing options...
86FUBAR Posted March 17, 2008 Share Posted March 17, 2008 it, TBI. i see a MAP(manifold absolute pressure) sensor, so unless I'm mistaken, a carb wouldnt have one. My 86 2.8L with a carb has a map sensor Link to comment Share on other sites More sharing options...
Eagle Posted March 17, 2008 Share Posted March 17, 2008 I didn't notice that you are in the Bahamas. Remove the air intake hose and post a photo of the "air induction device" so we can see if it's a carb or a throttle body. That looks like the intake hose for a TBI model, but a look inside would be definitive. Link to comment Share on other sites More sharing options...
Beachbum1236 Posted March 18, 2008 Author Share Posted March 18, 2008 going to get the pics soon, work got in the way yesterday so i am going to try to get them up soon. :cheers: Link to comment Share on other sites More sharing options...
Beachbum1236 Posted March 21, 2008 Author Share Posted March 21, 2008 Here are some pictures of the inside under the cap. In my opinion from working on 2 stroke engines, it looks pretty similar to the carburetors to those, a it different though. Link to comment Share on other sites More sharing options...
mjeff87 Posted March 21, 2008 Share Posted March 21, 2008 Throttle body injection (TBI) Sounds like a semantic difference to me.... Jeff Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 21, 2008 Share Posted March 21, 2008 Throttle body injection (TBI) Sounds like a semantic difference to me....Jeff Sure is. Your friend probably got the "pressure carburetor" terminology from the pressure regulator package under the injector in the TB. Link to comment Share on other sites More sharing options...
DirtyComanche Posted March 22, 2008 Share Posted March 22, 2008 A pressure carb is those found in chainsaws and some lawnmowers and such. Fuel flow to the nozzle/jet is regulated by air pressure not float bowl fuel height. They can run at any angle (normally). It's sorta like mechanical fuel injection, but it still uses a venturi to provide fuel atomization - a major drawback. And no, I've never seen a pressure carb on a vehicle but if anybody did it it'd be the british. I've seen pressure carbs on aircraft engines though. However, they're crap. Link to comment Share on other sites More sharing options...
mvusse Posted March 22, 2008 Share Posted March 22, 2008 Sure looks like a fuel injector hanging over top of the throttle body to me. Link to comment Share on other sites More sharing options...
Eagle Posted March 24, 2008 Share Posted March 24, 2008 Throttle body injection (TBI) Sounds like a semantic difference to me.... Jeff It is throttle body injection. But the difference is not semantic. A carburetor works on the principle of suction. The high velocity of the air stream as it passes through the carburetor venturi (or venturis, if it's a 2-bbl or 4-bbl) creates a low pressure, which sucks fuel out of the carburetor float bowl(s) through the jets. The fuel pump works at approximately 7 psi, and all it does is pump the gas up to the float bowls. The gas is not pumped from the bowl(s) to the venturis -- it is sucked by vacuum. Throttle body injection is just the opposite. The fuel pump sends gas directly to the injector(s) under relatively high pressure, and when the injector(s) fire(s) the gas is squirted into the air stream under pressure, rather than being sucked in by vacuum in a carburetor. The difference is very much not semantic. It's a fundamental difference in the mode of operation. Link to comment Share on other sites More sharing options...
Beachbum1236 Posted March 25, 2008 Author Share Posted March 25, 2008 thanks for the info guys, I'll be sure to let him know. very good information also, thanks again for the replies. Chris :cheers: Link to comment Share on other sites More sharing options...
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