bigliltruck

So i am a new member and am hoping to find some help here. I have a 1989 p/u with a 3.0 the engine was junk and i swapped in a lw milage engine from an 88 runner. well after learning that nothing wa the same between these two engines as far as every sensor,injectors,engine harness and ect i finally got it all swapped over and it will start and run for about 3-10 seconds and then it dies. i have crossed the B+ and Fp terminals and tried starting it to makesure thepump stayed running and it has made no differance. I have gone over every wire and connector over an over and over and cannot find anything unhooked eveything is in its right place and all vacuum hoses are right. I am losing my mind and just cant seem to figure this out, so here is my finale attempt before i flatten it. Any help would be appreciated.

Innervision

I swaped an 88 engine into my 94 so I know what you had to go through. Did you swap everything electrical off your 89 engine onto your 88 donor engine? And I mean everything. Could be an intake/throttle sensor.. air flow, throttle body etc.

Sounds like the engine gets running and then a sensor leans out or increases the air to fuel mixture and kills the engine.

I know the resistance on some of the 88 sensors were different from later engines thats why the connectors were changed.

bigliltruck

the only things i did not change are the distributor, cold start injector, and tps. i will swap the tps today and see what happens

Innervision

I had to swap the distributor as well. My 94 harness would not connect to the 88 distributor. I also just used the plenum and all attached sensors off the 94 and bolted it to the 88 engine. That way I knew all my sensors were correct for the ecu and harness.

you are going to an 89 so there may be some differences from my swap to a 94.

bigliltruck

well atfirst i used the 88 engine harness and it pplugged in the computer and everything so i thought i had it the only thing i really had to change ws the coil to the 88 but when i turn the key to on it would start turning over so i looked closr and found that even tho the plugs were the same that the wiring was different. Well then i tore it down and but everything 89 back in including harness the distributor has the same plug with same color wires so i figure i was ok there. now everything works except it doesnt run, lol thats just a minor flaw tho right?

TNRabbit

Make sure the VAFM electronics & all the intake tubing is connected. It won't run without them.

bigliltruck

i finally figured it out and it was something simple like i knew it was going to be. It ended up that the MAF off the 89 had a stuck flapper inside of it. i put on a new one and shes running awesome. thankyou

MudHippy

Yep, that'd do it!

However, you should have been able to detect that in a much more timely manner if you'd simply checked the ECU for codes. I know that because that's how I was able to diagnose a similar condition on mine. I believe, IIRC, that a code 31 showed up. Could've been 32. Anywho, the vane/flap wasn't closing all the way. It ran fine, and I didn't even notice it untill one day when I heard something humming as soon as I turned the key in the ignition switch to the ON position without starting the engine. I'd never noticed it before and it struck me as being very odd. The sound only went away when I turned the key to the OFF position. That sound, as it turned out, was the fuel pump being switched on prematurely by the AFM. Curious as to what it was I then checked for codes which led me directly to the AFM. Which I fixed by disassembling and cleaning it out. It had some dirt in there from a recent mud run that had filled the air box full of the stuff and saturated the air filter. The air filter stopped the big chunks of mud, but alot of muddy water was able to make it through.

In the future, ALWAYS check for codes first. It's just too easy to do, and too easy to run around in circles trying figure out why the engine won't run or won't run well.

bigliltruck

yea i had checked for codes and couldnt get any, which i believe is because i had the ecu out and i imagine that with the battery unhooked for so long it cleared the codes for me, which was awfully helpful. LOL