[shooter]

Great and you're welcome.

 

[bstrooper]

Hey Shooter, Thanks for the great info, I'm getting ready to do this conversion and have some questions for the group. I read your tutorial and might be repeating some things but the thread has been quiet for a while so I thought I'd give it a bump. My first question is about the fuel pump etc., I recently put a new in tank fuel pump into my trooper and would like to use it if possible. What about a fuel regulator or bypass regulator? Something like this, http://www.amazon.com/dp/B00MWNOEMI?psc=1, I know it is cheap and I will get what i pay for but does anyone think it would work, it does seem to have a fuel return which would make it a bypass regulator, but they don't come right out and say it. Or there is something more like this, http://www.amazon.com/Holley-12-803...sbs_263_1?ie=UTF8&refRID=1Q8J9R5F8PFQKZMY4RCH, but it only goes down to 4.5psi. Or should I just suck it up and put in a new pump and regulator now? I know I will have more questions, but that is all for now. Thanks Ben

 

[Apeiron]

I'm not a fan of using generic chinesium components in the fuel system, and that regulator is for fuel injection. It'd be a PITA trying to set the fuel pressure with any accuracy at 4% of the scale.

That Holley regulator would be fine, but the unpolished version is half that price. Mr. Gasket makes an ok one too, I think it's the 2015. I'm partial to the Mallory 4309 but it's complete overkill (and over budget) in this application

 

[oldestisuzuist]

If you are using a Weber carb use the Holley 12-804 regulator http://www.amazon.com/Holley-12-804-Fue ... ley+12-804
It has two outlet ports, use one for the carb supply, the other for a gauge or a return or plumb in both with a few extra fittings, or just plug it.
I'm not sure if it would reduce the 38psi of a new EFI pump down to the 3psi a weber likes, but it might with a return. I would also be concerned about the clamp type fuel line connections holding the EFI pressure. You may have to use a low pressure electric pump & suck fuel through the in-tank pump & strainer.

 

[Apeiron]

I'm not sure if it would reduce the 38psi of a new EFI pump down to the 3psi a weber likes, but it might with a return. I would also be concerned about the clamp type fuel line connections holding the EFI pressure.

Pumps don't make pressure, restrictions do. If there's no EFI regulator, there's no EFI pressure.

 

[geoffinbc]

Shouldn't be an issue for a bypass regulator, and it would save a lot of plumbing and dropping the tank. It's not the pressure that causes any problems at all, it's the volume. The stock return system can already handle the return volume, so why not use it?

Agreed. Keep the in tank pump and plumb a bypass style fuel system. Fuel stays cooler, pressure stays more consistent and there is never the possibility of vapor lock. Remember pumps don't make pressure they only make flow. The restriction to flow makes pressure. Whatever you set the pressure to with your regulator will be the operating pressure.

The best example of this is a pressure washer. Take the high pressure hose off the pump and fire it up. What happens? Nothing but slightly more water coming out. Without the tiny orifice at the end of the wand there is nothing to restrict flow and build pressure. Fuel systems are the same.

 

[ubs_lover]

Hi, I have a friend who want to convert his 4ZE1 FI to Weber Carb, but it's an auto unit. Is there any sensor or wiring for the Auto Tranny that affected with the conversion?

 

[PPCLI-JIM]

im doing the same thing. From the bits of info im getting the transmission will have to be shifted manually .

 

[RickP]

im doing the same thing. From the bits of info im getting the transmission will have to be shifted manually .

With a little bit of extra work, there is no reason the transmission can't work like it did with EFI. You'll just have to fab up a bracket for the TPS and hook the TV cable up to the linkage also.

 

[ubs_lover]

im doing the same thing. From the bits of info im getting the transmission will have to be shifted manually .

With a little bit of extra work, there is no reason the transmission can't work like it did with EFI. You'll just have to fab up a bracket for the TPS and hook the TV cable up to the linkage also.

Can you gives us some more detail about how to do it?
I think it's still related with this thread's topic.

 

[RickP]

im doing the same thing. From the bits of info im getting the transmission will have to be shifted manually .

With a little bit of extra work, there is no reason the transmission can't work like it did with EFI. You'll just have to fab up a bracket for the TPS and hook the TV cable up to the linkage also.

Can you gives us some more detail about how to do it?
I think it's still related with this thread's topic.

I've personally never did it with an Isuzu, but as I mentioned in another thread, I installed an Aisin transmission in a carburated car using the factory computer and wiring that came with the transmission. Since your buddy's vehicle already has the transmission, wiring and computer, you just need to hook up the things that the transmission computer needs. I would have to see a schematic of the wiring and what the end of the TPS looks like. On my conversion, I made a bracket that I bolted the TPS to and then ran a spring from the TPS arm to the throttle linkage. I also made a bracket that the TV (throttle valve) cable aka kickdown cable attached to the linkage.

 

[hagasn]

what would be some of the reason for converting the EFI motor to carb? if i'm not mistaken the 2.6 had 120hp @ the crank and my 2.3 4DZ1 had 96 hp stock.

 

[DSUZU]

what would be some of the reason for converting the EFI motor to carb?

1. The Isuzu "ITEC" has some nasty habits. Most involve idle issues. Another is the annoying (design) tendency to fast idle if you coast to a stop. This personally irritates me.
2. A carb conversion really cleans up under the hood and makes a lot of stuff easier to get to.
3. A well done carb conversion "might" be more dependable (in the long run) than an EFI given fuel pump failures etc. (ever try to push start an EFI with a dead battery? Ain't happening.
4. Personal "fine tuning". EFI has certain "emission" (and performance) limiting parameters that are not adjustable (spark curve, etc.) that with a carb conversion, you can custom tailor your distributor, carb mixture, size etc.
These are some reasons. Some have claimed to see a boost in performance and fuel mileage too. Dennis
NOTE: technically, it is illegal to convert, and if you have emissions inspection, don't even think about it. D.

 

[oldestisuzuist]

what would be some of the reason for converting the EFI motor to carb? if i'm not mistaken the 2.6 had 120hp @ the crank and my 2.3 4DZ1 had 96 hp stock.

Many foreign countries had a carbureted 2.6 engine rated at 115hp. The US had the EFI version to meet emission standards.

 

[hagasn]

i thought the only difference between the 2.3 and 2.6 was the intake side and EFI, the bottom and top end are the same?

 

[1991Casper]

Tagging this.

Thanks for the awesome thread.

 

[DSUZU]

i thought the only difference between the 2.3 and 2.6 was the intake side and EFI, the bottom and top end are the same?

Other than bore and stroke, valve covers are different, oil pan is different, timing belt and crank pulleys are different. You can swap the oil pans and trade engines back and forth. There is also something about a flywheel spacer, but I don't remember exactly what it was. Tranny bell housing patterns are tha same, but the 2.3s usually had a cable clutch while the 2.6s were hydraulic. Dennis

 

[gruff54]

There is also something about a flywheel spacer, but I don't remember exactly what it was. Dennis

Someone correct me if I'm wrong, just be nice! :wink:
Coming from a fuzzy memory, it's the plate between the block and bellhousing. I think the 2.6 is thicker than the 2.3? If you want to know for sure, ask the man (Jerry).

Mike

 

[speedrover]

How to Convert a 2.6L EFI to Carburetor

This tutorial applies only to non-air conditioned vehicles, manual transmission only and to non-emissions vehicle. Additionally, this applies only to the U.S. model 2.6L (4ZE1) which fits the below description. Vehicles with a/c and automatic transmissions will have issues of which I have no familiarity. The following modifications may only be used on vehicles for off road use only and in compliance with all local, state, and federal laws, rules, and regulations.

Parts Needed

1. Intake manifold with thermostat housing from 2.3L (4ZD1) Isuzu[/*]
2. Stock carburetor (Federal) from 2.3L (California versions have an Electronic Control Module (ECM) Only the Federal Version will be discussed[/*]
3. Distributor w/vacuum advance (Federal) and distributor hold down bracket from 2.3L[/*]
4. If possible, obtain a few inches of the wiring harness and connector which plugs into the 2.3L distributor/coil connector[/*]
5. Low pressure inline electric fuel pump[/*]
6. Fuel Pump Regulator[/*]
7. Tubing for new fuel pickup tube[/*]

Under the Hood (easiest if hood is removed)

Mine did not have the EGR pipe nor any A.I.R. Parts. If yours does, remove any items which would otherwise prevent the removal of the complete intake assembly.

1. Disconnect and remove battery[/*]
2. Put vehicle in neutral and apply parking brake / chock wheel for manual transmission[/*]
3. Drain coolant (radiator petcock) and remove upper radiator hose[/*]
4. Disconnect heater hose at passenger side lower intake fitting[/*]
5. Loosen fuel cap[/*]
6. Disconnect fuel return line from fuel pressure regulator and fuel line from injector rail[/*]
7. Disconnect fuel vapor line from intake[/*]
8. Disconnect ground wires from intake[/*]
9. Disconnect wire to water temperature gauge sending unit (I remove the sending unit and installed it to the 2.3L due to my knowing it was good[/*]
10. Disconnect all electrical connectors routed to engine which would prohibit the removal of the complete intake assembly[/*]
11. Remove PCV hose from intake[/*]
12. Disconnect hose from rear of valve cover at the air cleaner ducting tube[/*]
13. Disconnect MAF sensor from air cleaner[/*]
14. Disconnect hoses/lines form charcoal canister / remove charcoal canister[/*]
15. Remove air cleaner and duct work[/*]
16. Disconnect throttle cable from throttle body[/*]
17. Disconnect electrical connector to coil and remove coil[/*]
18. Disconnect round white connector to distributor/coil[/*]
19. Disconnect vacuum lines in any manner you prefer[/*]
20. Remove throttle body and common chamber[/*]
21. Remove lower intake[/*]
22. Remove brackets on passenger side inner fender along with remaining vacuum lines and associated parts[/*]
23. Though it may not be necessary, loosen power steering belt, disconnect power steering pump bracket and lower the assembly out of your way[/*]
24. Drop the fuel tank or cut an access port through the rear floor so that the fuel pump can be accessed[/*]
25. Remove fuel pump assembly[/*]
26. Remove sediment screen from bottom of fuel pump[/*]
27. Measure and record the overall length of the fuel pump[/*]
28. Remove fuel pump from bracket[/*]
29. Purchase, etc, tubing and cut it to a length equal to that measured from the the bottom of the fuel pump to the end of it's fitting which resides in a short section of rubber fuel line. This will now be the new fuel pickup tube[/*]
30. Insert tubing into rubber fuel line and clamp same[/*]
31. Reinstall fuel pump bracket with new fuel pickup tube to the fuel tank[/*]
32. Reinstall fuel tank or secure floor section to floor. (I cut a rectangular opening in the rear floor. I then used metal stock as "stops" for the cut out section. These were attached underneath the floor on the rear side. I attached two small hinges on the front side. This worked out very well.[/*]
33. Make sure the distributor rotor button has been indexed to the distributor hold down or other location. Do not allow the vehicle to be moved if in gear. This will simplify the installation of the 2.3L distributor.[/*]

Vehicle Cabin / Interior

1. Remove console[/*]
2. Disconnect ECM[/*]
3. Remove ECM[/*]

Installation of 2.3L Manifold / Distributor & Coil / Carburetor

1. Clean passenger side surface of cylinder head thoroughly[/*]
2. Obtain a sheet of 20/1000th brass shim material[/*]
3. Looking at the center of the passenger side cylinder head, you'll see a rectanglar recess. On it's left hand side, you'll observe a small, tube-shaped raised section of aluminum. This is used as an oil return path. The 2.3L intake has an opening which aligns with the recess. This area needs to be blocked or the result will be oil leakage.[/*]
4. Make a pattern to size and shape of the cylinder head side of the intake manifold opening[/*]
5. Transfer pattern to brass shim stock and cut[/*]
6. Sealer should be applied to approximately the 1/8" outside edge of both sides of the plate[/*]
7. I prefer the much thicker fel-pro intake manifold gasket over the factory gasket. Your choice.[/*]
8. Install the intake manifold, gasket, and shim stock to cylinder head. Torque to spec. If done correctly, the shim / block is located between the intake manifold gasket and cylinder head.[/*]
9. An alternative or addition to the brass is to cut to size and shape a good quality intake gasket material and 3/16' or 1/4" steel or aluminum plate. This can be drilled and installed on the "outside" area of the manifold using the two studs to which the 2.3L mechanical fuel pump attached. You'll need two nuts for the studs.[/*]
10. I chose to remove the studs from the cylinder head and went with bolts only for attaching the intake manifold. I thought it gave a cleaner appearance and it appeared that the two upper center studs would interfere with the installation of the weber 32/36 carburetor.[/*]
11. Additional block off plates will be necessary for EGR related equipment[/*]
12. To aid with installation of the manifold, I temporarily installed (finger tight only) studs to the upper rear/front bolt holes. I then slid the intake on, began bolting and removed the studs at the appropriate time and replace them with bolts.[/*]
13. Install the ignition coil[/*]
14. Connect wire to water temp sending unit and to the oil pressure gauge if it was disconnected[/*]
15. Install the distributor (check distributor shaft O-ring and replace if necessary) hold down bracket and distributor (there are two sizes of hold down brackets. My 2.6L bracket would not work, thus the need for the 2.3L bracket)[/*]
16. Connect heater hose to manifold[/*]
17. Examine thermostat and replace as needed[/*]
18. Obtain upper radiator hose for 2.3L and install. I purchased a 2.3L universal ribbed hose[/*]
19. Install new fuel pump as near and below the tank as possible[/*]
20. Install the fuel pump regulator in engine compartment[/*]
21. I removed my charcoal canister, vapor lines and fuel return line. You may or may not choose to follow this path.[/*]
22. I am currently running mine with the fuel cap loosened for venting. I'll do a more permanent fix soon.[/*]
23. Run 12 volt power to the fuel pump. I made a new circuit with a circuit breaker and relay. You can use the wiring which powered the factory fuel pump.[/*]
24. Install carburetor and fuel lines when you're comfortable to do so. Install throttle cable and brackets to carburetor throttle linkage (fabricate as necessary). You will have a much easier time if you replace the f/i throttle cable with the shorter carburetor throttle cable.[/*]
25. Connect PCV to new carburetor[/*]
26. Route hose from rear of valve cover to large fitting beneath carburetor, passenger side. I am installing a small K&N breather to the valve cover fitting; doing away with the hose.[/*]

Wiring Distributor and Tachometer

1. The 2.6L wiring to the distributor consists of four wires; red, green, blue, white. Red will provide switched hot to the distributor/coil. The other three wires became inert upon removal of ECM.[/*]
2. Two wires exit from the 2.3L distributor/coil wiring harness. One wire is black/yellow and the other black/red[/*]
3. Reinstall battery. Connect as necessary to perform any tests[/*]
4. The red wire of the 2.6L harness connects to the black/yellow of the 2.3L for switched hot. The red wire can also be used to provide voltage to the automatic choke.[/*]
5. Remove tachometer from instrument panel[/*]
6. Exiting from the rear of the tachometer circuit board are five wires. One of them is black/red. Be cautious. The black ground wire exiting from the tach has red dots. The signal wire will have a black stripe. I noticed on an 88 model the signal wire was light blue with a black stripe.[/*]
7. Cut the black/red wire a couple of inches from the tach going toward the electrical connector. Strip the end of the remaining black/red wire from the tach.[/*]
8. Splice a new wire to that end. There are 3-4 lugs on the back side of the tachometer. An alternative to cutting and splicing at the tach is to crimp a small ring connector to the wire end and attach to the corresponding lug/terminal. Make sure the new wire can reach the wiring at the distributor.[/*]
9. Splice the other end of the new wire to the black/red wire which originates from the distributor/coil.[/*]
10. Locate and install all ground wires to the manifold which were removed from the 2.6L manifold[/*]
11. Fill the radiator with water only.[/*]
12. Start and run motor[/*]
13. It may be necessary to adjust carburetor and ignition timing[/*]
14. My engine is now happiest at 6* BTDC @ 800 rpm when fully warmed. This coincides with the specs for a 2.3L 4ZD1. I've been advised to move my timing back to it's original 12* BTDC for better fuel mileage, etc. I tried 12* several times and my engine would start and run fine, however, It would run on when I tried to turn it off. With [email protected], it starts, runs, and shuts down just fine. The timing advances well; blah, blah, blah. I have since timed my engine to 12* with no issues.[/*]
15. When all is well, drain water and add proper coolant mix. I would also change the oil/filter.[/*]
16. When all is settled, I am going to begin removing wiring harnesses from the engine compartment and will update this tutorial as I progress.[/*]

Acknowledgments

I wish to thank the following people whom without their help I would have never attempted or successfully completed this conversion:

• moondoggie98. He was the first to respond to my questions, was there for any other question and gave me the confidence to proceed.[/*]
• Jerry (JLEMOND) who provided parts, instructions, and guidance throughout this endeavor. Many times he had to beat it into me until I finally grasped what he was telling me. Thank you forever and a day Jerry.[/*]
• To other members at Planetisuzoo.com who provided assistance, moral support and encouragement, I thank you too.[/*]
• To my good friend Mike who provided the expertise on setting up my carburetor. [/*]

Photos

http://i276.photobucket.com/albums/kk32 ... -Small.jpg

Block - Off Plate Pics
http://i276.photobucket.com/albums/kk32 ... -Small.jpg

http://i276.photobucket.com/albums/kk32 ... -Small.jpg

http://i276.photobucket.com/albums/kk32 ... -Small.jpg

http://i276.photobucket.com/albums/kk32 ... -Small.jpg

Is the "Igniter" used on the carb version?

 

[DSUZU]

No. Whole different type ignition system. 2.6 is an optic, 2.3 is a hall effect. Dennis