Considering a non electric injection pump. (1 Viewer)

Joined
Dec 15, 2019
Messages
71
Location
Colville Wa.
Expert advice needed
Im getting tired of the smoky choky cold starts. I have replaced everything related to fuel delivery except the ECU and the trouble remains unchanged. I can get a new ECU from Amayama for about $1300 and maybe fix the problem. or I can switch to a not electric pump
and for sure fix the problem. How convoluted is it to swap to a non electric pump. Detailed advice Please. I have a 91 LJ78 with Manual transmission. Completely rebuilt top to bottom. Engine has new everything.
Thanks.
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
7,434
Location
Victoria, BC, Canada
Expert advice needed
Im getting tired of the smoky choky cold starts. I have replaced everything related to fuel delivery except the ECU and the trouble remains unchanged. I can get a new ECU from Amayama for about $1300 and maybe fix the problem. or I can switch to a not electric pump
and for sure fix the problem. How convoluted is it to swap to a non electric pump. Detailed advice Please. I have a 91 LJ78 with Manual transmission. Completely rebuilt top to bottom. Engine has new everything.
Thanks.

I used to have smoky starts too, but my issues was low compression from an abused engine (had rust in the cylinders at one time that had left pitting). I also hated it. With more glowing (up to 3 cycles) I could get a clean start. Since then I replaced the short block with a good compression one. Also lucked upon a brand new injection pump and bought brand new injectors. Runs like a top now.

Air from a bad primer pump or leaky fuel lines can cause the smoky starts too. But from the sounds of it, your problem is a lot more complicated.

Having a manual transmission makes it a lot easier for you to go to a mechanical injection pump. Make sure to buy the injection pump from a 2LT-II (1989 and later). The earlier 2LT pump is different in a few ways, and also only has a 9mm plunger (later one is a 10mm plunger). A 3L pump will be missing the boost compensator, so isn't the best option either.

Go to Megazip, and carefully compare the LJ77 to the LJ78 drawings. This will help you figure out exactly what you need in the engine bay.

I've come across a few threads that have detailed this swap over the years. Try searching to see what you can find. Minor details like throttle linkage, tachometer will need to be overcome.
 

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