Reinstalling Mikuni after Chinese Weber fail.

[GodRamIt]

Hey all,

First. Thanks for allowing me to join your cool forum.

Ive been driving Mini-Trux for 35 years, 4wd and 2wd.

This is my first Mitsubishi, so far I have noticed that under the hood these trucks are laid out better than my Toy.

My new pickup is an ‘89 4wd. 2.6L.

The guy that owned it before me installed the China Weber. I’m not a huge fan of aftermarket on Jap trux.

The vacuum lines are numerous and homeless, I need a little help.

Ive seen quite a few schematics in this forum, not quite what I’m looking for.

Does anyone know of a circuit by circuit breakdown of the vacuum lines on these trux ?

As is the truck has is getting 11mpg on my commute and has a pretty bad hesitation so I need help.

Engine is low mile rebuild, 165psi across the board, no cat.

Bought it with an external leak head gasket, I fixed it, gasket was damaged by the rebuilder during installation.

Installed new radiator, and 8” two way truck boxes behind the seat, sounds awesome. Retro sound did a great job on those.

Ordered factory manuals from eBay last night.

Thanks in advance for any help.


Also looking for skid plate, not one that costs half of what I paid for the truck.

Kenny

[FMS88]

Glad to have you aboard. Look at the pdfs in Post#8 of this thread:
http://www.mightyram50.net/vbulletin...3354#post73354 (http://www.mightyram50.net/vbulletin/showthread.php/8147-1988-mighty-max-carburetor-vacuum-diagram-needed(actual-photos)?p=73354#post73354)

The book is for 87-88 models, but the 89 should be very similar if not identical. It contains better hose diagrams than the FSM; even gives the specs of the plastic connectors. It also describes the Mikuni's "features" and how to test or adjust them.

[geezer101]

If you swap the bad Chinese knock off for a genuine, it will radically improve your truck. There are a number of problems with the knock-offs that can't be rectified due to poor manufacturing and design. You already have everything to do the conversion and the Mikuni is not only a step back in all round performance, but is expensive and difficult to work on. A properly set up Weber can improve your economy up to 25mpg which is better than stock. Just an opinion. You also have the option of either the 32/36 Weber or the 38DGES which is another step up in performance.

[GodRamIt]

If you swap the bad Chinese knock off for a genuine, it will radically improve your truck. There are a number of problems with the knock-offs that can't be rectified due to poor manufacturing and design. You already have everything to do the conversion and the Mikuni is not only a step back in all round performance, but is expensive and difficult to work on. A properly set up Weber can improve your economy up to 25mpg which is better than stock. Just an opinion. You also have the option of either the 32/36 Weber or the 38DGES which is another step up in performance.


I realize the Weber is a sound option, have used them on several Toyota’s and Suzuki’s in the past. Your feedback is much appreciated, and well noted.

[GodRamIt]

Glad to have you aboard. Look at the pdfs in Post#8 of this thread:
http://www.mightyram50.net/vbulletin...3354#post73354 (http://www.mightyram50.net/vbulletin/showthread.php/8147-1988-mighty-max-carburetor-vacuum-diagram-needed(actual-photos)?p=73354#post73354)

The book is for 87-88 models, but the 89 should be very similar if not identical. It contains better hose diagrams than the FSM; even gives the specs of the plastic connectors. It also describes the Mikuni's "features" and how to test or adjust them.

Thanks so much for the info, I used your post to well equip myself with every factory manual on eBay.

[GodRamIt]

One more question for the tech savvy Mitsubishi tuners.

Will the distributor function in a stand alone fashion and without the emissions system ?

Thanks in advance for your help.

[geezer101]

The distributor only needs the coil to run. The emissions control module uses signals from the factory carb to open and close vacuum circuits and can't alter ignition timing like an ECU for injection. One of the bonuses for deleting the Mikuni...

[xboxrox]

The distributor only needs the coil to run. The emissions control module uses signals from the factory carb to open and close vacuum circuits and can't alter ignition timing like an ECU for injection. One of the bonuses for deleting the Mikuni...
geezer, is that true for all years of these trucks..?

[SubGothius]

geezer, is that true for all years of these trucks..?

For all carb'd years, yes. For the carb'd years with electronic ignition, the dizzy has its own ECU that operates independently of the Mikuni carb ECU. Vacuum advance can simply be fed directly from the carb or, I recently learned, from the manifold. Turns out the only reason for feeding the advance "ported vacuum" from the carb just above the closed throttle plate is to eliminate vac advance during idle for improved idle emissions. Using manifold vac will apply advance during idle and reduce operating temps at idle. The barb in the base of the carb (not higher up on the carb body) will supply manifold vac, or you can use the "tree" of barbs screwed into the manifold itself. Just make sure you disconnect this and cap the manifold-vac barb if you need an emissions test.

[xboxrox]

Thanks sub :thumbup: