from injection to carburetor in my XJ

Hi, somebody could help me please.

I got a 1991 XJ I want to convert from Injection to carburetor, I would like to know which manifold and carburetor should I use or if I need somethiing else.

Thanks

Any particular reason?

I'd probably make an adapter plate to go under the carb (don't know which one - hadn't thought about that yet,) and see about getting a later manifold - the "half-moon" from 1999 and up is a candidate. Mainly due to getting better distribution of the fuel mix than anything else.

My original question stands, thought - Why for do you want to do this? Are you having trouble? It may be cheaper to fix the problem you're having than to open up a whole bunch of new ones...

5-90

Why would you want to?

i keep thinking about it also

you might be able to find an Offenhauser intake but the only ones i could find worked for the 258 to 1990.as everybody else has said unless the only thing you do is drive on flat ground its just not worth it.

Fitting a carburetor on to a fuel injected car is somewhat common in countries where the fuel injection parts or qualified mechanics required to fix the car are hard to find or prohibitively expensive.

I have seen it done to cars that were built in transition years from carb to injection where carb and fuel injected models were avaliable around the same time (think 80s Volkswagen, toyota, throttle-body injected cars, etc). Usually this is done to cars where the carb manifold and ignition electronics interchange easily.

The 4.0 motor was never offered with a carburetor in any vehicle so there are no bolt-on parts for this. You would have to adapt a carb system from something else. I have heard distributor and related ignition parts from the eariler AMC/Jeep 4.2 engine work on the 4.0 but I haven't ever confirmed this myself. I would also think the carb used with these motors could be made to fit with a spacer or there may be a single barrel carb that fits the same bolt pattern as the 4.0 manifold, I don't know.

If you have a 2.5l 4 cylinder XJ maybe its easier because that motor came with a carburetor for a while.

Thanks for your help, the reason is that is hard to find a good mechanic in injection in my country Ecuador, and most of the mechanics knows the carburetor
systems, and also this jeep is gonna to work in a ranch where is even harder to find an injection mechacnic.

What really happen is that I had already done this conversion and I had the problems you told me. I show you some pictures, We also work with old jeeps.

So looks like I have to learn injection, Where is a good school to start and what scanner should I look for, Thanks again to all.

Since you have a 1991, it should be OBD-compliant (OBD-1, in fact) and that makes it MUCH easier to find a scanner for. Just find something OBD-1 that understands Chrysler, and you should be able to find it for somwhat under US$200. (I'm not sure about the exchange rate down there, offhand.)

The Chrysler system is a little simpler than the earlier RENIX, but I prefer working on the RENIX because it's more responsive to troubleshooting and diagnosis (I'm just funny that way - I came up on points & condensers and Rochesters, helping an uncle with his collection of Corvettes.)

I think you'll also find that the Chrysler system is easier to find parts for - while RENIX used a lot of GM parts and the Chrysler used somewhat less, there are more Chrysler systems "out there," which makes it more popular with parts manufacturers.

Considering my own experience with the stuff, fuel injection is really not much different from carburetion - once you make shift your mental gears to realise it's a "feedback" system with greater control, and not an "open-ended" system like a carburetor. Meaning that it actually looks at the end products (that's what the Oxygen Sensor is for) and modifies its own output accordingly - which can result in greater efficiency and greater power output. I have actually come to prefer simple fuel injection systems over carburettors - for that reason, mainly.

I don't know what your educational system is like, either - but if you check around for smaller colleges (we call them "community colleges" up here) and get their course catalogues, you might find some basic automotive courses that you could take. This would give you a firm grounding in automotive systems, and you could then decide if you want to take your education further afterwards - many colleges and trade schools up here offer mechanic certification, and I see no reason why that would not hold in any sufficienty industrialised country (one with a sufficient automotive population, for instance, or with a good deal of farming/ranching equipment powered by internal combustion engines.)

On a side note - your English is quite good. Are you using a translator, or were you taught it in school?

5-90

Thnks, Here we use US dollars as normal money, I would like to go USA to learn FI in a fast track or in Self Paced here, I was an exchange student in my senior year in High School at Fillmore Indiana, by the way looks quite interesting your page.

TJ

Thank you. Can you think of anything I should add (I've got a few things in the pipline for addition now, but I'm trying to make it a "community-driven" tech archive.)

Small World Note - I grew up in Lafayette, IN. I've probably been through Fillmore a few times, since I drove all over the place...

One of the best things you can do for yourself is to find a Factory Service Manual (FSM) for your rig, and maybe get a general Fuel Injection or Chrysler Engine Control book as well. Expect to pay US$80-100 for the FSM set, but it's well worth it! Also, it's worth checking Ebay, since they pop up there from time to time (and are usually a little cheaper there.) Also, I have a 1991FSM, and I'd be willing to help you troubleshoot. I'd have to figure out what it would cost to copy Chaper 14 - Fuel Systems to send to you, but I could probably be talked into that as well.

5-90

5-90, I do believe export model XJs destined for countries without strict emissions controls got the O2 sensor deleted. The ECM uses other inputs like the TPS and map sensor to controll the air/fuel ratios though probably not as efficiently. My personal experience is that the Chrysler FI system found in 91 and newer XJs is reliable and that problems can usually be attibuted to a limited range of critical sensors. I think it is possible for the educated owner to diagnose and repair the system using manuals like 5-90 suggested.

I thought I read about there being propane kits out there for the 4.0, it this is the case then you should be able to use most of the conversion parts from that to get the computer out of the loop and then fit the carb on what ever adapter they have.