topley

Hi All,
so my racecar hasn't turned a wheel in anger for a few years now but I used to start it and idle every couple of months. At some point it went off the charger and my optima 680 which is a pain to get to went dead and I was unable to jump or start since before covid. Got another battery a month or so ago and no start... wasn't getting fuel. Turns out the rubber line from the tank to pump had degraded and collapsed and I assume all my cranking burned out the pump as it was no longer working once I confirmed DME relay and power to it. Replaced strainer, pump and fuel filter and now have fuel at the rail. It started! Yay! but only running on #4 cylinder! Boo! Tach bounced when I would crank and does idle for a while on that one cylinder (surprising) so I hope that rules out speed and ref sensors????? I can hear all the injectors clicking away when I put my stethoscope on each one. Pulled #1 spark plug and checked with current spark plug and a known good one I had laying around and neither had spark when cranking touching ground. Cap and rotor look good... but? Before I throw money at cap, rotor, wires and plugs is there anything else obvious I should check?


For all intents and purposes car is a 86 ish 944 turbo with a Vitesse turbo and vmaf+ that was making 270 at the rear wheels last time I had it on the dyno.

Thanks
Jay

fast951

Since you are getting fuel and spark on 1 cylinder you can rule out the followings:
- DME
​​​- DME relay
- Speed & Ref sensors
- Fuel pump.

Things to check:
- Determine which cylinder is always firing. Or is the firing order totally random?
- is the dist rotor loose? Spinning on the shaft?
- did you examine the dist cap?
- did you foul the spark plugs?
- did you try checking spark plugs on every cylinders to verify which is firing. Once you have one spark firing, use it's plug wire to test the other non firing cylinders. (Checking for bad wires).

Ignition distribution across cylinders is purely mechanical. It's the function of dist cap, rotor and wires.

The injectors clicking does not mean they are supplying the correct amount of fuel. Clogged injectors will click. But fuel delivery is compromised. Hopefully you drained and refreshed the fuel before trying to run the engine?

topley

Yes its cylinder 4 that is the only one firing. Cap and rotor looked good Rotor was solid. Yes emptied all the gas in the tank, pump and filter... mostly onto myself. Once I had those all changed out put 4 gal of fresh 101 in and ran a couple quarts through the end of the rail with the DMR relay ports jumpered. Looks like I'll have to pull the intake to get to all the plug wires and I'm only a couple miles from RC engineering so I might just have the injectors cleaned and checked for good measure.

Thanks

Gage

My bet would be that the injectors are stuck. You're on the right path with bridging the relay and running the fuel circuit with fresh fuel. As crude as it sounds, often a firm smack at the base of the injector body will free them up. I use a foot long hardwood stick, end cut at an angle, to gain access to the ridge on the injector body.

GPA951s

+1… you had issues with fuel.. line, fp ect you just didnt make it to “ the end of the line”

Glue Guy

It sounds like a good chance the injectors are plugged.

It’s easy enough to pull the fuel rail and put each injector each into an individual bottle while still connected on the rail. I’ve done this with 4 empty water bottles. Just tape them on. Obviously use all caution and disconnect the coil to distributor cap wire so there’s no spark. And with no flames nearby and cold engine.

this will allow you to see if you have anything jacked up with one or more injectors.

topley

Well I hope I didn't keep everyone on pins and needles... So I tried to test spark better and my Nology wires were fused to the distributor cap and getting them off #2 and #3 spark plugs destroyed them so I figured I better at least do plugs, dist cap and rotor along with the wires. New NGK's, Beru wires and rotor and Bosch cap took a couple of days to gather. I know its been a while but I have had the fuel rail off before but it was on there pretty good. Since I had the other parts I decided not to force the rail to check the injectors so just gave them a rap with my box wrench and tightened everything back down. Installed the DME relay and flipped the battery cutoff and she fired right up. Idled and came to temp with good oil pressure etc. Don't know if it was one thing or a combo but I'm back in business.

Thanks all
Jay