another fc starts then dies thread:(
 

okay... please help! jus bought an 87 fc turbo with a fresh pineapple rebuild. car ran fine. drove it for about 700 miles and then sat for about 2 years. was started up every few weeks and warmed to temp the entire time it sat. drove up and down the road. boosted. no prob felt great. all the sudden it wont stay running. starts dies starts dies. unplug the maf and it runs for about 10 seconds instead of 1. plug it back in and back to 1 second run time. put a smoke machine on it and fixed a few leaks. no more smoke. it was coming out the tailpipes and nowhere in the engine bay. put a aem fuel pressure reg. on it and set it to 40psi. also has a walboro 255lph fuel pump. so i doubt its the fuel pump.

so basically it runs 5 times longer with the maf unhooked.

PLEASE HELP!!!!!!:nod:

Check the flapper on the AFM to see if it will move freely.
The last car I got was stored 2 years and the AFM was corroded and I had to disassemble the AFM and clean the flapper as it was stuck and wouldn't move.

first things first, do a compression test. 95psi or greater is good !

If that checks off, verify spark, and fuel. If your getting fuel pressure, and spark and still not starting,spray some starter fluid to see if it fires up, if it does, it could be the injectors not spraying, stuck, or dripping[flooding]. I send my injectors to RC engineering , cost $25 per injectors to get services

or it could be the maff getting stuck as mentioned above..

compression is fine has spark and fuel. does the same thing with starting fluid. also the injectors were sent out to RC and reinstalled already. maf has been replaced with another used one. still the same.

could i possibly have gotten another bad maf?
would the map sensor have anything to do with it?

Sounds like the car is dying at changeover. (When the ECU switches from the startup procedure to running condition)

There are tons of reasons this could happen, anything from one of the mandatory sensors being WAY out of whack (IAT, Coolant temp, AFM) and possibly even a wild signal from something else. I've seen a few S4s with a corroded sensor ground on the engine do something similar.

Can you give it some gas and keep it running at say 2500rpm or above?

I just remembered a huge vac leak can cause this too. You say you smoked it, but how about holding your flapper door on the AFM slightly open and then starting it? :)

It might shut off the fuel if it's totally shut IIRC.

i will try holding the flapper open a lil and see what happens. as far as giving it pedal. it makes no difference when the afm is plugged in when its unplugged however u can feather the throttle a bit.

If it stays running if you keep it above 3000 rpm or so, chances are it is just a giant vacuum leak causing it not to be able to stay idling.

check the maf. my car was doing the same thing. Switched them out and it idles perfect now.

ive switched the maf out for another. same thing:(

@ funkjaw
it doesnt respond to pedal at all when the maf is plugged in. only when its unplugged does it try to stay running.

so now i got nothing. not even dash lights and i found rat shit all over the engine bay. little bastards! think i might have to swap harnesses? anyone done it?

so i cleaned up all the wiring and put the car back together and now the starter seems to be shit. getting another one in the am. anyways... how much fuel pressure should i have? i have a walboro 255lph fuel pump. a mild streetport pineapple engine and a bnr stage 1 turbo. stock injectors.

jus wondering what i should set my pressure at?

well... i got it back together and it still does the same thing. starts and dies. tried a different ecu. same thing.:scratch: this is driving me crazy! i wanna drive it!

Jumper the fuel check connector. If that doesn't improve things then jumper the solid Black wire in the circuit Opening relay to the Brown wire in the same relay.

where is the circuit opening relay?

and what color are the wires coming out of the fuel check connector?

The two wires in the check connector are Black and Brown and the plug is Yellow but likely covered in a Black rubber boot.

The relay is Black and Yellow and located just to the right of the steering column just under the dash.

EDIT: And the check connector is located in the same harness that supplies the wires to the Boost sensor and is located fairly close to it.

when i jumper the check connector it starts up easier but still dies. with the relay jump do i pull the plug and jumper the two connectors? (tried that no difference) or does the relay have to be plugged in when i jump the wires?

The relay needs to be plugged in. Solid Black wire (not Black/White) to Brown wire.

jumped it with the relay plugged in and could rev it a bit:) whats the problem part?

So it runs longer and you could rev it, but it still dies out. Correct? And how high can you rev it to?

EDIT: With key to on and the TPS plug disconnected what is the voltage reading on the Brown wire? Should be 5 volts.

i could rev it all the way. heard the turbo spool and the bov for the first time
and yes it still died

First check the Brown wire voltage as suggested.

EDIT: Also remove the jumper at the check connector but leave the one at the relay alone.

Also, w/key to on measure the Black wire at the check connector as it should read 0 volts as it is a ground. Make sure the jumper at this connector is removed.

ok... everything is like u said. 5 volts at tps brown wire. 0 at check connector ground.

now what?