Ashman

So, last week I did some work to my 86 N.A. Now I can't get it to start and I'm not sure the best way to isolate what the problem is.

The original goal was to replace the vacuum lines, but I did a couple of of other "While you're in there" jobs along the way.

Here's what I did:

1) Removed the fuel rail and injectors.
2) Removed the intake, J-boot between the MAF sensor and the throttle body.
3) Removed the old melted vacuum lines between the throttle body, fuel pressure regulator, fuel pressure dampener, vacuum valve, thermo valve, etc.
4) Replaced the four gaskets between the intake and block with new ones as one of those had an area where it had blown out.
5) Replaced the intake, all of the associated hose hookups, throttle body, J-boot, etc.
6) replaced the gaskets and "hats" on the injectors and flushed them out.
7) Replaced the injectors and fuel rail.

After all of that, I can't get the car to start. It turns over fine, catches and then immediately dies. I'm about to spring for a fuel pressure test kit to see if that's the issue. However, my fuel pump is brand new, so if pressure is the problem I'm 99% sure that it isn't the source of the problem. Also my spark plugs, wires, and distributor are all practically brand new as well, so I'm thinking it's got to be the fuel. Maybe I'll just pull the rail again and check everything over.

Dunno. Any thoughts as to what the problem might be?

Pin It

I had a similar issue about 1 week ago after doing exactly the same work. I could keep the car running but it was stumbling very hard. My tank was on empty and I'm sure that there was some air (and 4 month old gas) in the fuel lines. I ended up adding a few gallons of fresh gas, let the fuel pump run for a few minutes and she started/ran fine after a few attempts. If your pump is new, then there is probably even more air in the system that needs to be bled out.

Ashman

To let the fuel pump run, I just turn to the "accessory" slot and let her sit there for a bit?

V2Rocket

the 944 fuel pump does NOT run with key on engine off.
it only runs when the engine is rotating, ie cranking and running.

look up the "944 dme relay jumper" and build one, this directly connects fuel pump and DME to battery power (rather than thru ignition switch). this will quickly fill the rail up and should let the car start if that's the problem.
importantly, then you should put the DME relay back in and see if the car starts up again easily (since there's already fuel), this is a test of the relay and ign. switch function.

Van

AFM plug?

thomasmryan

Ashman

I did remember to re-plug the AFM. So, that shouldn't be the problem.

So. Next step... Pull the DME relay. Jumper 30 - 87b for about 5 minutes.

Got it. I'll give that a try tonight. Thanks for the help everyone. I really appreciate it.

V2Rocket

5 mins, no maybe 5-10 seconds.
easier if you pull the cap nut off the end of the rail so there's somewhere for the air to be displaced.

Ashman

Well, that was a no go.

Purged the air out. Still stumbles and won't start.

Took the fuel rail, injectors, spark wires, j-boot off over the weekend trying to see if I could see anything amiss.

Couldn't find anything, so I put it all back together and still have the same problem. Even switched out the DME relay just for good measure.

I'm wondering... Is it possible that after years of not having a vacuum applied the FPV is now stuck in a wide open or wide closed position?

I guess I'll find a fuel pressure tester rig and try that next...

Tiger03447

Pin It

You may want to check the brass idle air screw on the throttle body to make sure it is letting some air through. If you had a vacuum leak before, someone may have turned that thing all the way down to keep the idle in check.

Dwizle

Check DME temp sensor is not unplugged or broken wire also check injector wiring harness make sure you don't have any shorts 30+ yr old insulation is pretty brittle..

Scott at Team Harco

Do you have someone near you that has a known good DME? It's worth swapping to see if that might be the problem.

You would be surprised how many times this has been the problem - even in my little corner of the 944 galaxy...

Fastbackjack

Make sure your distributor rotor is tight and where it should be. I've seen it more than once where the little Allen head screw comes out allowing the rotor to spin independently. It will sometimes fire, backfire or sputter, but never fully run. Just a thought ...

Chalt

This what mine was doing. Bought a snake camera and found out my head gasket is leaking into #1. I also had a disconnected vacuum line that I thought was the cause. Mine will start after a few tries, stumbles etc. Hope you find out what's up with yours. Mine is an '86 NA too.