he_mech_usmc

Hey everyone,
The title says what's happening. I finally got the car fired up after LOTS of wiring "adjustments."

I replaced the external fuel pump, cleaned the fuel tank, replaced rubber fuel lines, rechecked wiring, checked the battery for 12v, replaced bad fuses and relays, straightened out the 4 pin issue in the spare tire well, turned the key and cranked the car twice for approx 15 sec each time, let the car sit, check for leaks, no leaks found, cranked the car again and it started.

the car would sit and idle what I would call normally, I attempted to manually actuate the throttle while tuning the timing and there was no throttle response.

the car would "bog" down and and want to stall out and then would come back to a normal idle...then the backfire.

The backfire shut the car down, it didn't lock the motor up and it still turns over, I pulled the pan and everything is intact and as it should be. I'm just a little leery about trying to start the car again and looking for a little insight as to what could cause this, and what to check before attempting to restart the car.

I was not able to check for vacuum while the car was running, so I don't know if there is any. There was only one thing that did not fare well from the backfire. The cold start base that the PO rigged blew apart when the motor backfired. And by rigged I mean tried to silicone a plastic barb fitting where the hose attaches.

Again, any help is always appreciated

Thanks,
Josh

LT Texan

Horribly clogged fuel filter?

Mrmerlin

it sounds like you have the timing too far advanced do this put the engine at TDC the distributor rotor should be pointing at the little cut mark in the housing with the cap removed put the dist so the front edge of the rotor is just at the hash mark then try to start the car also check to make sure you have the ignition wires in the correct positions the engine is numbered at the right bank front 1 to 4 then the left bank is 5 to 8

Dave928S

Backfire sounds like ultra lean ... bog down sounds like not enough fuel. Fuel issues seem the logical likely issue ... but spark and timing should also be checked. If timing was way out that could give those symptoms too ... have you checked that your static timing is in the ballpark and that you'll get advance?

You need to go through the procedure for checking CIS fuel delivery and pressures before you do anything else. Sections 24 and 25 in the WSM ... and then double check ignition.

Replace that cold start plastic fitting with a new one ... they're cheap.

Edit: took a while to post .... +1 on what Mrmerlin said ... static timing.

he_mech_usmc

Dan...thanks for the thought, I will try to get a new filter to try.

he_mech_usmc

sorry merlin and dave, computer is being slow. I will get at it tomorrow morning and see what happens

Glenn Evans

I agree with what Dave said: it sounds very lean. Check the static timing and troubleshoot iaw the workshop manual. If the fuel delivery rate meets, or is near spec (1350 ml per 30 seconds), you should then measure the fuel pressures. The CIS fuel pressure gauge kit is only about $80 from 928sRus or whoever. Ensure that you buy a CIS kit; most are for efi and don't have the correct fittings.

Specultating prematurely, your cold control pressure probably will be too high, so the control pressure regulator (aka warm-up regulator) isn't able to enrich the mixture enough to start a cold engine. A common workaround for this is to enrich the mixture, so the engine can be started but will run rich when warm.

The control pressure regulator fails either because the bimetallic strip fails, or the inlet screen is blocked. If you remove the fuel lines from the top of the regulator, you should be able to blow through the fuel chamber. If you can't, the inlet screen is blocked. I suggest filling the inlet with paint thinner to soften the deposits and, if necessary, carefully unblocking the holes in the screen with a sharp needle and blowing any debris out the outlet.

Glenn Evans
'80 928 Petrolblaumetallic
5 speed
Sydney, Australia