Hey guys, just put this engine in (1986 Toyota Pickup, Turbo) a couple weeks ago, it came out of a totalled 1986 Turbo 4Runner, and has been running great. The other day I parked it to change out the rear 3rd member, and when I went to start it up last night, it turned over, fired, and then died as if it couldn't get enough fuel. The fuel filter is new, and I cracked the seal and turned on the key to see if the fuel pump was giving fuel, and that's all good.
Did some research, and found a thread online where someone said it was the MAF, so I swapped that out of the 4Runner (known good), and now it fires, and if I give it gas it will stay running... horribly at best. It jumps all over the RPM range with a steady throttle, coughs, and pops like its getting fuel one second, and no fuel the next.

Any Ideas? thanks...

 

Okay, just started the truck and it works fine.... weirdness

 

weird... i was going to guess vacuum leak. anyways, nice find on that turbo motor!

 

Turning the key to "on" shouldn't cause the fuel pump to run so "cracking a seal" and getting fuel doesn't mean much.

 

It's an electric fuel pump. As far as I know, all the stock EFI fuel pumps turn on when the key is in the "On" position.
Or maybe I'm wrong. But every one I've ever come across does

 

Yeah there's a horror story behind that motor. I was driving around my little town here looking for Toyotas with expired tabs, and saw this 2nd Gen 4Runner sitting in a driveway with a brand new one next to it. So I go up to look at it, and it's in almost MINT condition. I walk around back and whadda ya know, there's a TURBO SR5 plaque on the back of it! Thinking that there's no way it would ever be for sale, I almost walk away from it when I see a FOR SALE sign on the front seat!
After bugging the lady for a couple months, she finally sells it to me for $2500, but then I can't get it to start. She sends it to her mechanic on her dime because she told me it ran, and the mechanic went through and rebuilt the injectors.
A couple days later I'm driving it back from work, and I hit oil on the road and roll it down an embankment!

 

I know what you mean- that turning the key on "pre-charges" the fuel system so fuel is there and ready, however, our trucks don't work that way. If you turn the key to 'on'... power is delivered to the ECU and other devices like the cigarette lighter, radio, etc.; but not the fuel pump.

When you turn the key to 'Start', the ignition switch energizes the COR (Circuit Opening Relay) via the "STA" wire, which in turn energizes the fuel pump. Once the engine is running, air flow through the VAFM keeps the COR turned on, and consequently the fuel pump, and thus the engine, keeps running
... or at least that's how it is supposed to work.

 

When i turn the key on in my 4 runner... I hear the pump kick on for a few seconds and then go off???

I did just like he did one time. Cracked the fuel line. Nothing happened. Truned on the key and then fuel everywhere!.. Lol... Sooooooo. Whats the deal? Lol.

 

I'm not above saying I'm wrong so I'll go check over the wiring diagrams I have and see exactly how they are.